MLX90614 Family

Melexis Technologies NV

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Datasheet

MLX90614 family
Datasheet
Single and Dual Zone
Infra Red Thermometer in TO-39
REVISION 11 - JUNE 15, 2017
3901090614
Features and Benefits
Small size, low cost
Easy to integrate
Factory calibrated in wide temperature
range:
-40°C+125˚C for sensor temperature and
-70°C+380˚C for object temperature.
High accuracy of 0.5°C in a wide
temperature range (0°C…+5C for both Ta
and To)
High (medical) accuracy calibration
Measurement resolution of 0.02°C
Single and dual zone versions
SMBus compatible digital interface
Customizable PWM output for continuous
reading
Available in 3V and 5V versions
Simple adaptation for 8V…16V applications
Sleep mode for reduced power
consumption
Different package options for applications
and measurements versatility
Automotive grade
Application Examples
High precision non-contact temperature
measurements
Thermal Comfort sensor for Mobile Air
Conditioning control system
Temperature sensing element for
residential, commercial and industrial
building air conditioning
Windshield defogging
Automotive blind angle detection
Industrial temperature control of moving
parts
Temperature control in printers and
copiers
Home appliances with temperature control
Healthcare
Livestock monitoring
Movement detection
Multiple zone temperature control up to
127 sensors can be read via common 2
wires
Thermal relay / alert
Body temperature measurement
Ordering Information
Part No.
MLX90614
Temperature
Code
E (-40°C...85°C)
K (-40°C…125°C)
Package
Code
SF (TO-39)
- Option Code
- X X X
(1) (2) (3)
Standard
part
-000
Packing
form
-TU
(1) Supply Voltage/ Accuracy
A - 5V
B - 3V
C - Reserved
D - 3V medical accuracy
(2) Number of thermopiles:
A – single zone
B – dual zone
C – gradient compensated*
(3) Package options:
A – Standard package
B – Reserved
C – 35° FOV
D/E – Reserved
F – 10° FOV
G – Reserved
H – 12° FOV (refractive lens)
I – 5° FOV
K – 13°FOV
Example:
MLX90614ESF-BAA-000-TU * : See page 2
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
REVISION 11 - JUNE 15, 2017
3901090614
1. Functional diagram
Figure 1: Typical application schematics
2. General Description
The MLX90614 is an Infra Red thermometer for non-
contact temperature measurements. Both the IR
sensitive thermopile detector chip and the signal
conditioning ASSP are integrated in the same TO-39 can.
Thanks to its low noise amplifier, 17-bit ADC and
powerful DSP unit, a high accuracy and resolution of the
thermometer is achieved.
The thermometer comes factory calibrated with a digital
PWM and SMBus (System Management Bus) output.
As a standard, the 10-bit PWM is configured to
continuously transmit the measured temperature in
range of -20120˚C, with an output resolution of 0.14˚C.
The factory default POR setting is SMBus.
The MLX90614 is built from 2 chips developed and manufactured by Melexis:
The Infra Red thermopile detector MLX81101
The signal conditioning ASSP MLX90302, specially designed to process the output of IR sensor.
The device is available in an industry standard TO-39 package.
Thanks to the low noise amplifier, high resolution 17-bit ADC and powerful DSP unit of MLX90302 high accuracy and
resolution of the thermometer is achieved. The calculated object and ambient temperatures are available in RAM of
MLX90302 with resolution of 0.01°C. They are accessible by 2 wire serial SMBus compatible protocol (0.02°C
resolution) or via 10-bit PWM (Pulse Width Modulated) output of the device.
The MLX90614 is factory calibrated in wide temperature ranges: -40°C12C for the ambient temperature
and -7C380°C for the object temperature.
The measured value is the average temperature of all objects in the Field Of View of the sensor. The MLX90614 offers
a standard accuracy of ±0.C around room temperatures. A special version for medical applications exists offering an
accuracy of ±0.2˚C in a limited temperature range around the human body temperature.
It is very important for the application designer to understand that these accuracies are only guaranteed and
achievable when the sensor is in thermal equilibrium and under isothermal conditions (there are no temperature
differences across the sensor package). The accuracy of the thermometer can be influenced by temperature
differences in the package induced by causes like (among others): Hot electronics behind the sensor, heaters/coolers
behind or beside the sensor or by a hot/cold object very close to the sensor that not only heats the sensing element in
the thermometer but also the thermometer package.
This effect is especially relevant for thermometers with a small FOV like the xxC and xxF as the energy received by the
sensor from the object is reduced. Therefore, Melexis has introduced the xCx version of the MLX90614. In these
MLX90614xCx, the thermal gradients are measured internally and the measured temperature is compensated for
them. In this way, the xCx version of the MLX90614 is much less sensitive to thermal gradients, but the effect is not
totally eliminated. It is therefore important to avoid the causes of thermal gradients as much as possible or to shield
the sensor from them.
As a standard, the MLX90614 is calibrated for an object emissivity of 1. It can be easily customized by the customer for
any other emissivity in the range 0.1…1.0 without the need of recalibration with a black body.
The 10-bit PWM is as a standard configured to transmit continuously the measured object temperature for an object
temperature range of -20°C…120°C with an output resolution of 0.1C. The PWM can be easily customized for
virtually any range desired by the customer by changing the content of 2 EEPROM cells. This has no effect on the
factory calibration of the device.
J1
CON1
SCL
SDA
GND
Vdd
C1 value and type may differ
in different applications
for optimum EMC
U1
MLX90614
1
P W M
SDA
C1
M LX906 1 4 connection to SM Bus
4
Vss
SCL
Vz
MLX90614Axx : Vdd=4.5...5.5V
3
2
Vdd
0.1uF
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 3 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
The PWM pin can also be configured to act as a thermal relay (input is To), thus allowing for an easy and cost effective
implementation in thermostats or temperature (freezing / boiling) alert applications. The temperature threshold is
user programmable. In a SMBus system this feature can act as a processor interrupt that can trigger reading all slaves
on the bus and to determine the precise condition.
The thermometer is available in 2 supply voltage options: 5V compatible or 3V (battery) compatible. The 5V can be
easily adopted to operate from a higher supply voltage (8…16V, for example) by use of few external components (refer
to Applications information” section for details).
An optical filter (long-wave pass) that cuts off the visible and near infra-red radiant flux is integrated in the package to
provide ambient and sunlight immunity. The wavelength pass band of this optical filter is from 5.5…14µm (except for
xCH and xCI type of devices which incorporate uncoated silicon lens).
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 4 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
3. Contents
Features and Benefits
Features and BenefitsFeatures and Benefits
Features and Benefits
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Application
Application Application
Application Examples
ExamplesExamples
Examples
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Ordering Information
Ordering InformationOrdering Information
Ordering Information
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1. Functional diagram
1. Functional diagram1. Functional diagram
1. Functional diagram
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2. General Description
2. General Description2. General Description
2. General Description
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3. Contents
3. Contents3. Contents
3. Contents
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4. Glossary of Terms
4. Glossary of Terms4. Glossary of Terms
4. Glossary of Terms
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5. Maximum ratings
5. Maximum ratings5. Maximum ratings
5. Maximum ratings
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6. Pin definitions and descriptions
6. Pin definitions and descriptions6. Pin definitions and descriptions
6. Pin definitions and descriptions
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7. Electrical Specifications
7. Electrical Specifications7. Electrical Specifications
7. Electrical Specifications
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7.1. MLX90614Axx ..................................................................................................................................... 9
7.2. MLX90614Bxx, MLX90614Dxx .......................................................................................................... 11
8. Detailed description
8. Detailed description8. Detailed description
8. Detailed description
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8.1. Block diagram .................................................................................................................................... 13
8.2. Signal processing principle ............................................................................................................... 13
8.3. Block description ............................................................................................................................... 14
8.3.1. Amplifier ...................................................................................................................................... 14
8.3.2. Supply regulator and POR .......................................................................................................... 14
8.3.3. EEPROM ...................................................................................................................................... 14
8.3.4. RAM ............................................................................................................................................. 17
8.4. SMBus compatible 2-wire protocol ................................................................................................. 17
8.4.1. Functional description ................................................................................................................ 17
8.4.2. Differences with the standard SMBus specification (reference [1]) ........................................ 18
8.4.3. Detailed description ................................................................................................................... 18
8.4.4. Bit transfer .................................................................................................................................. 19
8.4.5. Commands .................................................................................................................................. 20
8.4.6. SMBus communication examples .............................................................................................. 20
8.4.7. Timing specification .................................................................................................................... 21
8.4.8. Sleep Mode ................................................................................................................................. 22
8.4.9. MLX90614 SMBus specific remarks ........................................................................................... 23
8.5. PWM .................................................................................................................................................. 24
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 5 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
8.5.1. Single PWM format ..................................................................................................................... 25
8.5.2. Extended PWM format ............................................................................................................... 26
8.5.3. Customizing the temperature range for PWM output ............................................................. 27
8.6. Switching Between PWM / Thermal relay and SMBus communication ........................................ 29
8.6.1. PWM is enabled .......................................................................................................................... 29
8.6.2. Request condition ....................................................................................................................... 29
8.6.3. PWM is disabled ......................................................................................................................... 29
8.7. Computation of ambient and object temperatures ....................................................................... 30
8.7.1. Ambient temperature Ta ............................................................................................................ 30
8.7.2. Object temperature To ............................................................................................................... 30
8.7.3. Calculation flow .......................................................................................................................... 31
8.8. Thermal relay .................................................................................................................................... 32
9. Unique
9. Unique 9. Unique
9. Unique Features
FeaturesFeatures
Features
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10. Performance Graphs
10. Performance Graphs10. Performance Graphs
10. Performance Graphs................................
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34
10.1. Temperature accuracy of the MLX90614 ...................................................................................... 34
10.1.1. Standard accuracy .................................................................................................................... 34
10.1.2. Medical accuracy ...................................................................................................................... 36
10.1.3. Temperature reading dependence on VDD ............................................................................ 36
10.2. Field Of View (FOV) ......................................................................................................................... 38
11. Applications Information
11. Applications Information11. Applications Information
11. Applications Information
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11.1. Use of the MLX90614 thermometer in SMBus configuration ...................................................... 42
11.2. Use of multiple MLX90614s in SMBus configuration ................................................................... 42
11.3. PWM output operation .................................................................................................................. 42
11.4. Thermal alert / thermostat ............................................................................................................ 43
11.5. High voltage source operation ....................................................................................................... 44
12. Application Comments
12. Application Comments12. Application Comments
12. Application Comments
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13. Standard information regarding manufacturability of Melexis products with different soldering
13. Standard information regarding manufacturability of Melexis products with different soldering 13. Standard information regarding manufacturability of Melexis products with different soldering
13. Standard information regarding manufacturability of Melexis products with different soldering
processes
processesprocesses
processes
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14. ESD
14. ESD 14. ESD
14. ESD Precautions
PrecautionsPrecautions
Precautions
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15. FAQ
15. FAQ15. FAQ
15. FAQ
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16. Package Information
16. Package Information16. Package Information
16. Package Information
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16.1. MLX90614xxA ................................................................................................................................. 50
16.2. MLX90614xCC ................................................................................................................................. 50
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 6 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
16.3. MLX90614xCF ................................................................................................................................. 51
16.4. MLX90614xCH ................................................................................................................................. 51
16.5. MLX90614xCI .................................................................................................................................. 52
16.6. MLX90614xCK ................................................................................................................................. 52
16.7. Part marking .................................................................................................................................... 53
16.8. Operating and storage humidity range ......................................................................................... 53
17. Table of figures
17. Table of figures17. Table of figures
17. Table of figures
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18. References
18. References18. References
18. References................................
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19. Contact
19. Contact19. Contact
19. Contact
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20. Disclaimer
20. Disclaimer20. Disclaimer
20. Disclaimer
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MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 7 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
4. Glossary of Terms
PTAT
P
roportional
T
o
bsolute
T
emperature sensor (package temperature)
POR
P
ower
O
n
R
eset
HFO
H
igh
F
requency
O
scillator (RC type)
DSP
D
igital
S
ignal
P
rocessing
FIR
F
inite
I
mpulse
R
esponse. Digital filter
IIR
I
nfinite
I
mpulse
R
esponse. Digital filter
IR
I
nfra
-
R
ed
PWM
P
ulse
W
ith
M
odulation
DC
D
uty
C
ycle (of the PWM) ;
D
irect
C
urrent (for settled conditions specifications)
FOV
F
ield
O
f
V
iew
SDA,SCL
S
erial
DA
ta,
S
e
rial
CL
ock
SMBus compatible communication pins
Ta
mbient
T
emperature measured from the chip
(the package temperature)
To
O
bject
T
emperature, ‘seen’ from IR sensor
ESD
E
lectro
-
S
tatic
D
ischarge
EMC
E
lectro
-
M
agnetic
C
ompatibility
ASSP
pplication
S
pecific
S
tandard
P
roduct
TBD
T
o
B
e
D
efined
Note: sometimes the MLX90614xxx is referred as the module.
5. Maximum ratings
Parameter MLX90614ESF-Axx
MLX90614ESF-Bxx
MLX90614ESF-Dxx
MLX90614KSF-Axx
Supply Voltage, V
DD
(over voltage) 7V 5V 7V
Supply Voltage, V
DD
(operating) 5.5 V 3.6V 5.5V
Reverse Voltage 0.4 V
Operating Temperature Range, T
A
-40°C+85°C -40°C+125°C
Storage Temperature Range, T
S
-40°C+125°C -40°C+125°C
ESD Sensitivity (AEC Q100 002) 2kV
DC current into SCL / Vz (Vz mode) 2 mA
DC sink current, SDA / PWM pin 25 mA
DC source current, SDA / PWM pin 25 mA
DC clamp current, SDA / PWM pin 25 mA
DC clamp current, SCL pin 25 mA
Table 1: Absolute maximum ratings for MLX90614
Exceeding the absolute maximum ratings may cause permanent damage.
Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 8 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
6. Pin definitions and descriptions
Figure 2: Pin description
Pin Name Function
SCL / Vz
Serial clock input for 2 wire communications protocol. 5.7V zener is available at
this pin for connection of external bipolar transistor to MLX90614Axx to supply
the device from external 8…16V source.
SDA / PWM
Digital input / output. In normal mode the measured object temperature is
available at this pin Pulse Width Modulated.
In SMBus compatible mode the pin is automatically configured as open drain
NMOS.
VDD External supply voltage.
VSS Ground. The metal can is also connected to this pin.
Table 2: Pin description MLX90614
Note:
for +12V (+8…+16V) powered operation refer to the Application information section. For EMC and isothermal
conditions reasons it is highly recommended not to use any electrical connection to the metal can except by the VSS pin.
With the SCL / Vz and PWM / SDA pins operated in 2-wire interface mode, the input Schmidt trigger function is automatically
enabled.
Bottom view
2 - SDA / PWM
4 - VSS
3 - VDD
1 - SCL / Vz
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 9 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
7. Electrical Specifications
7.1.
7.1.7.1.
7.1. MLX90614Axx
MLX90614AxxMLX90614Axx
MLX90614Axx
All parameters are valid for T
A
= 25 ˚C, V
DD
=5V (unless otherwise specified)
Parameter Symbol Test Conditions Min Typ Max Units
Supplies
External supply V
DD
4.5 5 5.5 V
Supply current I
DD
No load 1.3 2 mA
Supply current
(programming) I
DDpr
No load, erase/write EEPROM
operations 1.5 2.5 mA
Zener voltage Vz Iz = 75…1000μA (Ta=room) 5.5 5.7 5.9 V
Zener voltage Vz(Ta) Iz = 70…1000μA,
full temperature range 5.15 5.7 6.24 V
Power On Reset
POR level V
POR_up
Power-up (full temp range) 1.4 1.75 1.95 V
POR level V
POR_down
Power –down (full temp range) 1.3 1.7 1.9 V
POR hysteresis V
POR_hys
Full temp range 0.08 0.1 1.15 V
V
DD
rise time (10% to 90% of
specified supply voltage)
T
POR
Ensure POR signal 20 ms
Output valid
(result in RAM) Tvalid After POR 0.25 s
Pulse width modulation
1
PWM resolution PWMres Data band 10 bit
PWM output period PWM
T,def
Factory default, internal oscillator
factory calibrated
1.024 ms
PWM period stability dPWM
T
Internal oscillator factory
calibrated, over the entire
operation range and supply voltage
-10 +10 %
Output high Level PWM
HI
I
source
= 2 mA V
DD
-0.2 V
Output low Level PWM
LO
I
sink
= 2 mA V
SS
+0.2 V
Output drive current Idrive
PWM
Vout,H = V
DD
- 0.8V 7 mA
Output sink current Isink
PWM
Vout,L = 0.8V 13.5 mA
Continued on next page
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 10 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
Parameter Symbol Test Conditions Min Typ Max Units
SMBus compatible 2-wire interface
2
Input high voltage V
IH
(Ta, V) Over temperature and supply 3 V
Input low voltage V
IL
(Ta, V) Over temperature and supply 0.6 V
Output low voltage V
OL
Over temperature and supply, Isink
= 2mA 0.2 V
SCL leakage I
SCL
, leak V
SCL
=4V, Ta=+85°C 30 μA
SDA leakage I
SDA
, leak V
SDA
=4V, Ta=+85°C 0.3 μA
SCL capacitance C
SCL
10 pF
SDA capacitance C
SDA
10 pF
Slave address SA Factory default 5A hex
Wake up request t
wake
SDA low 33 ms
SMBus Request t
REQ
SCL low 1.44 ms
Timeout, low T
imeout,L
SCL low 27 33 ms
Timeout, high T
imeout,H
SCL high 45 55 μs
Acknowledge setup time Tsuac(MD) 8-th SCL falling edge, Master 1.5 μs
Acknowledge hold time Thdac(MD) 9-th SCL falling edge, Master 1.5 μs
Acknowledge setup time Tsuac(SD) 8-th SCL falling edge, Slave 2.5 μs
Acknowledge hold time Thdac(SD) 9-th SCL falling edge, Slave 1.5 μs
EEPROM
Data retention Ta = +85°C 10 years
Erase/write cycles Ta = +25°C 100,000 Times
Erase/write cycles Ta = +125°C 10,000 Times
Erase cell time Terase 5 ms
Write cell time Twrite 5 ms
Table 3: Electrical specification MLX90614Axx
Notes: All the communication and refresh rate timings are given for the nominal calibrated HFO frequency and will vary
with this frequency’s variations.
1. With large capacitive load lower PWM frequency is recommended. Thermal relay output (when configured) has
the PWM DC specification and can be programmed as push-pull, or NMOS open drain. PWM is free-running, power-up
factory default is SMBus, refer to section 8.6, “Switching between PWM and SMBus communication” for more details.
2. For SMBus compatible interface on 12V application refer to Application information section. SMBus compatible
interface is described in details in the SMBus detailed description section. Maximum number of MLX90614 devices on one bus
is 127, higher pull-up currents are recommended for higher number of devices, faster bus data transfer rates, and increased
reactive loading of the bus.
MLX90614 is always a slave device on the bus. MLX90614 can work in both low-power and high-power SMBus
communication.
All voltages are referred to the Vss (ground) unless otherwise noted.
Sleep mode is not available on the 5V version (MLX90614Axx).
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 11 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
7.2.
7.2.7.2.
7.2. MLX90614Bxx, MLX90614Dxx
MLX90614Bxx, MLX90614DxxMLX90614Bxx, MLX90614Dxx
MLX90614Bxx, MLX90614Dxx
All parameters are valid for T
A
= 25 ˚C, V
DD
=3V (unless otherwise specified)
Parameter Symbol Test Conditions Min Typ Max Units
Supplies
External supply V
DD
2.6 3 3.6 V
Supply current I
DD
No load 1.3 2 mA
Supply current
(programming) I
DDpr
No load, erase / write EEPROM
operations 1.5 2.5 mA
Sleep mode current Isleep no load 1 2.5 5 μA
Sleep mode current Isleep Full temperature range 1 2.5 6 μA
Power On Reset
POR level V
POR_up
Power-up (full temp range) 1.4 1.75 1.95 V
POR level V
POR_down
Power –down (full temp range) 1.3 1.7 1.9 V
POR hysteresis V
POR_hys
Full temp range 0.08 0.1 1.15 V
V
DD
rise time
(10% to 90% of
specified supply voltage)
T
POR
Ensure POR signal 20 ms
Output valid Tvalid After POR 0.25 s
Pulse width modulation
1
PWM resolution PWMres Data band 10 bit
PWM output period PWM
T,def
Factory default, internal oscillator
factory calibrated 1.024 ms
PWM period stability dPWM
T
Internal oscillator factory
calibrated, over the entire
operation range and supply voltage
-10 +10 %
Output high Level PWM
HI
I
source
= 2 mA V
DD
-0.25 V
Output low Level PWM
LO
I
sink
= 2 mA V
SS
+0.25 V
Output drive current Idrive
PWM
Vout,H = V
DD
- 0.8V 4.5 mA
Output sink current Isink
PWM
Vout,L = 0.8V 11 mA
Continued on next page
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 12 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
Parameter Symbol Test Conditions Min Typ Max Units
SMBus compatible 2-wire interface
2
Input high voltage V
IH
(Ta,V) Over temperature and supply VDD-0.1 V
Input low voltage V
IL
(Ta,V) Over temperature and supply 0.6 V
Output low voltage V
OL
Over temperature and supply,
Isink = 2mA 0.25 V
SCL leakage I
SCL
,leak V
SCL
=3V, Ta=+85°C 20 μA
SDA leakage I
SDA
,leak V
SDA
=3V, Ta=+85°C 0.25 μA
SCL capacitance C
SCL
10 pF
SDA capacitance C
SDA
10 pF
Slave address SA Factory default 5A hex
Wake up request t
wake
SDA low 33 ms
SMBus Request t
REQ
SCL low 1.44 ms
Timeout,low T
imeout,L
SCL low 27 33 ms
Timeout, high T
imeout,H
SCL high 45 55 μs
Acknowledge setup time Tsuac(MD) 8-th SCL falling edge, Master 1.5 μs
Acknowledge hold time Thdac(MD) 9-th SCL falling edge, Master 1.5 μs
Acknowledge setup time Tsuac(SD) 8-th SCL falling edge, Slave 2.5 μs
Acknowledge hold time Thdac(SD) 9-th SCL falling edge, Slave 1.5 μs
EEPROM
Data retention Ta = +85°C 10 years
Erase/write cycles Ta = +25°C 100,000 Times
Erase/write cycles Ta = +125°C 10,000 Times
Erase cell time Terase 5 ms
Write cell time Twrite 5 ms
Table 4: Electrical specification MLX90614Bxx, Dxx
Note: refer to MLX90614Axx notes.
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 13 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
8. Detailed description
8.1.
8.1.8.1.
8.1. Block diagram
Block diagramBlock diagram
Block diagram
Figure 3: Block diagram
8.2.
8.2.8.2.
8.2. Signal processing principle
Signal processing principleSignal processing principle
Signal processing principle
The operation of the MLX90614 is controlled by an internal state machine, which controls the measurements and
calculations of the object and ambient temperatures and does the post-processing of the temperatures to output them
through the PWM output or the SMBus compatible interface.
The ASSP supports 2 IR sensors (second one not implemented in the MLX90614xAx).The output of the IR sensors is
amplified by a low noise low offset chopper amplifier with programmable gain, converted by a Sigma Delta modulator
to a single bit stream and fed to a powerful DSP for further processing. The signal is treated by programmable (by
means of EEPROM contend) FIR and IIR low pass filters for further reduction of the band width of the input signal to
achieve the desired noise performance and refresh rate. The output of the IIR filter is the measurement result and is
available in the internal RAM. 3 different cells are available: One for the on-board temperature sensor and 2 for the IR
sensors.
Based on results of the above measurements, the corresponding ambient temperature Ta and object temperatures To
are calculated. Both calculated temperatures have a resolution of 0.0C. The data for Ta and To can be read in two
ways: Reading RAM cells dedicated for this purpose via the 2-wire interface (0.02°C resolution, fixed ranges), or
through the PWM digital output (10 bit resolution, configurable range).
In the last step of the measurement cycle, the measured Ta and To are rescaled to the desired output resolution of the
PWM) and the recalculated data is loaded in the registers of the PWM state machine, which creates a constant
frequency with a duty cycle representing the measured data.
81101
OPA ADC DSP
PWM
STATE MACHINE
Voltage
Regulator
90302
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 14 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
8.3.
8.3.8.3.
8.3. Block description
Block descriptionBlock description
Block description
8.3.1.
8.3.1.8.3.1.
8.3.1. Amplifier
AmplifierAmplifier
Amplifier
A low noise, low offset amplifier with programmable gain is used for amplifying the IR sensor voltage. By carefully
designing the input modulator and balanced input impedance, the max offset of the system is 0.5μV.
8.3.2.
8.3.2.8.3.2.
8.3.2. Supply regulator and POR
Supply regulator and PORSupply regulator and POR
Supply regulator and POR
The module can operate from 3 different supplies:
VDD = 5V MLX90614Axx
VDD = 3V MLX90614Bxx (battery or regulated supply)
VDD = 8V…16V MLX90614Axx few external components are necessary please refer to Applications information
section for information about adopting higher voltage supplies.
The Power On Reset (POR) is connected to Vdd supply. The on-chip POR circuit provides an active (high) level of the POR
signal when the Vdd voltage rises above approximately 0.5V and holds the entire MLX90614 in reset until the Vdd is higher
than the specified POR threshold V
POR
. During the time POR is active, the POR signal is available as an open drain at the
PWM/SDA pin. After the MLX90614 exits the POR condition, the function programmed in EEPROM takes precedence for that
pin.
8.3.3.
8.3.3.8.3.3.
8.3.3. EEPROM
EEPROMEEPROM
EEPROM
A limited number of addresses in the EEPROM memory can be changed by the customer. The whole EEPROM can be read
through the SMBus interface.
EEPROM (32X16)
Name Address Write access
To
max
0x00
Yes
To
min
0x01
Yes
PWMCTRL
0x02
Yes
Ta range
0x03
Yes
Emissivity correction coefficient
0x04
Yes
Config
Register1
0x05
Yes
Melexis reserved
0x06
No
Melexis reserved
0x0D
No
SMBus address (LSByte only)
0x0E
Yes
Melexis reserved
0x0F
Yes
Melexis reserved
0x10
No
Melexis reserved
0x18
No
Melexis reserved
0x19
Yes
Melexis
reserved
0x1A
No
Melexis reserved
0x1B
No
ID number
0x1C
No
ID number
0x1D
No
ID number
0x1E
No
ID number
0x1F
No
Table 5: EEPROM table
The addresses To
max
, To
min
and Ta range are for customer dependent object and ambient temperature ranges. For details see
section 8.5.3 below in this document
The address Emissivity contains the object emissivity (factory default 1.0 = 0xFFFF), 16 bit.
Emissivity = dec2hex[ round( 65535 x
ε
) ]
Where dec2hex[ round( X ) ] represents decimal to hexadecimal conversion with round-off to nearest value (not truncation).
In this case the physical emissivity values are
ε
= 0.1…1.0.
Erase (write 0) must take place before write of desired data is made.
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 15 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
PWM period configuration: Period in extended PWM mode is twice the period in single PWM mode.
In single PWM mode period is T = 1.024*P [ms], where P is the number, written in bits 15…9 PWMCTRL. Maximum period is
then 131.072 ms for single and 262.144 ms for extended. These values are typical and depend on the on-chip RC oscillator
absolute value. The duty cycle must be calculated instead of working only with the high time only in order to avoid errors
from the period absolute value deviations.
The address PWMCTRL consists of control bits for configuring the PWM/SDA pin as follows:
* Values are valid for nominal HFO frequency
Table 6: PWM control bits
The address ConfigRegister1 consists of control bits for configuring the analog and digital parts:
Note: The following bits / registers should not be altered (except with special toolscontact Melexis for such tools
availability) in order to keep the factory calibration relevant:
Ke [15...0]; Config Register1 [14...11;7;3]; addresses 0x0F and 0x19.
Table 7: Configuration register 1
Check www.melexis.com for latest application notes with details on EEPROM settings.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
PWM control bit meaning
0 - PWM extended mode
1 - PWM single mode
0 - PWM mode disabled (EN_PWM)
1 - PWM mode enabled (EN_PWM)
0 - SDA pin configured as Open Drain (PPODB)
1 - SDA pin configured as Push-Pull (PPODB)
0 - PWM mode selected (TRPWMB)
1 - Thermal relay mode selected (TRPWMB)
- PWM repetition number 0…62 step 2
- PWM period 1.024*ms (Single PWM mode) or 2.048*ms (Extendet PWM mode)
multiplied by the number written in this place (128 in case the number is 0)
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Config register bit meaning
1 0 0 - IIR (100%) a1=1, b1=0
1 0 1 - IIR (80%) a1=0.8, b1=0.2
1 1 0 - IIR (67%) a1=0.666, b1=0.333
1 1 1 - IIR (57%) a1=0.571, b1=0.428
0 0 0 - IIR (50%) a1=0.5, b1=0.5
0 0 1 - IIR (25%) a1=0.25, b1=0.75
0 1 0 - IIR (17%) a1=0.166(6), b1=0.83(3)
0 1 1 - IIR (13%) a1=0.125, b1=0.875
0 - Repeat sensor test "OFF"
1 - Repeat sensor test "ON"
0 0 - Ta, Tobj1
0 1 - Ta, Tobj2
1 0 - Tobj2
1 1 - Tobj1, Tobj2
0
- Single IR sensor
1 - Dual IR sensor
0 - Positive sign of Ks
1 - Negative sign of Ks
0 0 0 - FIR = 8 not recommended
0 0 1 - FIR = 16 not recommended
0 1 0 - FIR = 32 not recommended
0 1 1 - FIR = 64 not recommended
1 0 0 - FIR = 128
1 0 1 - FIR = 256
1 1 0 - FIR = 512
1 1 1 - FIR = 1024
0 0 0 - GAIN = 1 - Amplifier is bypassed
0 0 1 - GAIN = 3
0 1 0 - GAIN = 6
0 1 1 - GAIN = 12,5
1 0 0 - GAIN = 25
1 0 1 - GAIN = 50
1 1 0 - GAIN = 100
1 1 1 - GAIN = 100
0 - Positive sign of Kt2
1 - Negative sign of Kt2
0 - Enable sensor test
1 - Disable sensor test
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 16 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
On-chip filtering and settling time:
The MLX90614 features configurable on-chip digital filters. They allow customization for speed or noise. Factory default
configurations and the typical settling time and noise for the MLX90614 family are given below.
Device Settling time, sec Typical noise, °C rms Spike limit
MLX90614AAA, BAA, DAA
0.10
0.05
100%
MLX90614ABA, BBA
0.14
0.07
100%
MLX90614ACC, BCC
, DCC
0.14
0.18
100%
MLX90614
ACF, BCF
1.33
0.10
50%
MLX90614DCH, DCI, BCH, BCI
0.65
0.
10
80%
MLX90614
ACK, BCK
3.23
0.30
25%
Table 8: factory default IIR and FIR configuration, settling time and typical noise
Details on the filters are given in the application note “Understanding MLX90614 on-chip digital signal filters” available from
www.melexis.com.
The evaluation board, EVB90614 supported by PC SW allows easy configuration of the filters, while not requiring in-depth
understanding of the EEPROM.
The available filter settings and the settling times are listed below. Settling time depends on three configurations: single /
dual zone, IIR filter settings and FIR filter settings. The FIR filter has a straight forward effect on noise (4 times decreasing of
filter strength increases the noise 2 times and vice versa). The IIR filter provides an additional, spike limiting feature. Spike
limit defines the level of magnitude to which the spike would be limited – for example, 25% denotes that if a 20°C
temperature delta spike is measured the temperature reading by the MLX90614 will spike only 5°C.
Table 9: possible IIR and FIR settings
Note: Settling time is in seconds and depends on internal oscillator absolute value.
100% spike limit appears with the IIR filter bypassed, and there is no spike limitation.
Settling time (s) Settling time (s)
90614xAx 90614xBx, 90614xCx
xxx 000…011
100 100 0.04 0.06 100.00%
100 101 0.05 0.07 100.00%
100 110 0.06 0.10 100.00%
100 111 0.10 0.14 100.00%
101 100 0.12 0.20 80.00%
101 101 0.16 0.24 80.00%
101 110 0.22 0.34 80.00%
101 111 0.35 0.54 80.00%
110 100 0.24 0.38 66.70%
110 101 0.30 0.48 66.70%
110 110 0.43 0.67 66.70%
110 111 0.70 1.10 66.70%
111 100 0.26 0.42 57.00%
111 101 0.34 0.53 57.00%
111 110 0.48 0.75 57.00%
111 111 0.78 1.20 57.00%
000 100 0.30 0.47 50.00%
000 101 0.37 0.60 50.00%
000 110 0.54 0.84 50.00%
000 111 0.86 1.33 50.00%
001 100 0.70 1.10 25.00%
001 101 0.88 1.40 25.00%
001 110 1.30 2.00 25.00%
001 111 2.00 3.20 25.00%
010 100 1.10 1.80 16.70%
010 101 1.40 2.20 16.70%
010 110 2.00 3.20 16.70%
010 111 3.30 5.00 16.70%
011 100 1.50 2.40 12.50%
011 101 1.90 3.00 12.50%
011 110 2.80 4.30 12.50%
011 111 4.50 7.00 12.50%
Not recommended
FIR settingIIR setting Spike limit
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 17 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
8.3.4.
8.3.4.8.3.4.
8.3.4. RAM
RAMRAM
RAM
It is not possible to write into the RAM memory. It can only be read and only a limited number of RAM registers are of
interest to the customer.
RAM (32x16)
Name Address Read access
Melexis reserved
0x00
Yes
Melexis reserved
0x
0
3
Yes
Raw data IR channel 1
0x
0
4
Raw data IR channel 2
0x0
5
T
A
0x06 Yes
T
OBJ1
0x07 Yes
T
OBJ2
0x08 Yes
Melexis reserved
0x0
9
Yes
Melexis
reserved
0x
1F
Yes
Table 10: Ram addresses
8.4.
8.4.8.4.
8.4. SMBus compatible 2
SMBus compatible 2SMBus compatible 2
SMBus compatible 2-
--
-wire protocol
wire protocolwire protocol
wire protocol
The chip supports a 2 wires serial protocol, build with pins PWM / SDA and SCL.
SCL digital input only, used as the clock for SMBus compatible communication. This pin has the auxiliary
function for building an external voltage regulator. When the external voltage regulator is used, the 2-wire
protocol is available only if the power supply regulator is overdriven.
PWM/SDA Digital input / output, used for both the PWM output of the measured object temperature(s) or
the digital input / output for the SMBus. In PWM mode the pin can be programmed in EEPROM to operate as
Push / Pull or open drain NMOS (open drain NMOS is factory default). In SMBus mode SDA is forced to open
drain NMOS I/O, push-pull selection bit defines PWM / Thermal relay operation.
SMBus communication with MLX90614 is covered in details in application notes, available from www.melexis.com.
8.4.1.
8.4.1.8.4.1.
8.4.1. Functional description
Functional descriptionFunctional description
Functional description
The SMBus interface is a 2-wire protocol, allowing communication between the Master Device (MD) and one or more Slave
Devices (SD). In the system only one master can be presented at any given time [1]. The MLX90614 can only be used as a
slave device.
Generally, the MD initiates the start of data transfer by selecting a SD through the Slave Address (SA).
The MD has read access to the RAM and EEPROM and write access to 9 EEPROM cells (at addresses 0x00, 0x01, 0x02, 0x03,
0x04, 0x05*, 0x0E, 0x0F, 0x19). If the access to the MLX90614 is a read operation it will respond with 16 data bits and 8 bit
PEC only if its own slave address, programmed in internal EEPROM, is equal to the SA, sent by the master. The SA feature
allows connecting up to 127 devices (SA=0x00…0x07F) with only 2 wires, unless the system has some of the specific features
described in paragraph 5.2 of reference [1]. In order to provide access to any device or to assign an address to a SD before it
is connected to the bus system, the communication must start with zero SA followed by low R/W
¯
bit. When this command is
sent from the MD, the MLX90614 will always respond and will ignore the internal chip code information.
Special care must be taken not to put two MLX90614 devices with the same SA on the same bus as MLX90614 does not
support ARP [1].
The MD can force the MLX90614 into low consumption mode “sleep mode” (3V version only).
Read flags like “EEBUSY” (1 – EEPROM is busy with executing the previous write/erase), “EE_DEAD” (1 there is fatal
EEPROM error and this chip is not functional**).
Note*: This address is readable and writable. Bit 3 should not be altered as this will cancel the factory calibration.
Note**: EEPROM error signaling is implemented in automotive grade parts only.
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 18 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
8.4.2.
8.4.2.8.4.2.
8.4.2. Differences with the standard SMBus specification (reference [1])
Differences with the standard SMBus specification (reference [1])Differences with the standard SMBus specification (reference [1])
Differences with the standard SMBus specification (reference [1])
There are eleven command protocols for standard SMBus interface. The MLX90614 supports only two of them. Not
supported commands are:
Quick Command
Byte commands - Sent Byte, Receive Byte, Write Byte and Read Byte
Process Call
Block commands
Block Write and Write-Block Read Process Call
Supported commands are:
Read Word
Write Word
8.4.3.
8.4.3.8.4.3.
8.4.3. Detailed description
Detailed descriptionDetailed description
Detailed description
The PWM / SDA pin of MLX90614 can operate also as PWM output, depending on the EEPROM settings. If PWM is enabled,
after POR the PWM / SDA pin is directly configured as PWM output. Even if the device is in PWM mode SMBus
communication may be restored by a special command. That is why hereafter both modes are treated separately.
8.4.3.1.
8.4.3.1.8.4.3.1.
8.4.3.1. Bus Protocol
Bus ProtocolBus Protocol
Bus Protocol
Figure 4: SMBus packet element key
After every received 8 bits the SD should issue ACK or NACK. When a MD initiates communication, it first sends the address
of the slave and only the SD which recognizes the address will ACK, the rest will remain silent. In case the SD NACKs one of
the bytes, the MD should stop the communication and repeat the message. A NACK could be received after the PEC. This
means that there is an error in the received message and the MD should try sending the message again. The PEC calculation
includes all bits except the START, REPEATED START, STOP, ACK, and NACK bits. The PEC is a CRC-8 with polynomial
X8+X2+X1+1. The Most Significant Bit of every byte is transferred first.
SWrSlave Address A Data Byte
A
P
S
Start Condition
Sr
Repeated Start Condition
Rd
Read (bit value of 1)
Wr
Write (bit value of 0)
A
Acknowledge (this bit can be 0 for ACK and 1 for NACK)
S
Stop Condition
PEC
Packet Error Code
Master
-
to
-
Slave
Slave
-
to
-
Master
1
1
7
1
8
1
1
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 19 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
8.4.3.1.1.
8.4.3.1.1.8.4.3.1.1.
8.4.3.1.1. Read Word (depending on the command
Read Word (depending on the command Read Word (depending on the command
Read Word (depending on the command –
RAM or EEPROM)
RAM or EEPROM)RAM or EEPROM)
RAM or EEPROM)
Figure 5: SMBus read word format
8.4.3.1.2.
8.4.3.1.2.8.4.3.1.2.
8.4.3.1.2. Write Word (depending on the command
Write Word (depending on the command Write Word (depending on the command
Write Word (depending on the command –
RAM or EEPROM)
RAM or EEPROM)RAM or EEPROM)
RAM or EEPROM)
Figure 6: SMBus write word format
8.4.4.
8.4.4.8.4.4.
8.4.4. Bit transfer
Bit transferBit transfer
Bit transfer
Figure 7: Recommended timing on SMBus
The data on PWM / SDA must be changed when SCL is low (min 300ns after the falling edge of SCL). The data is fetched by
both MD and SDs on the rising edge of the SCL. The recommended timing for changing data is in the middle of the period
when the SCL is low.
SCL
Sampling data
SDA
Changing data
S
Wr
Slave Address
A
Data Byte Low
A
P
Command
A
Sr
Slave Address
Rd
1 7 1 1
8 1 1
7 1
8 1 1
………..
..
A
1
Data Byte High
A
8
1
PEC
A
8 1
S
Wr
Slave Address
A
Data Byte Low
A
P
Command
A
1
7
1
1
8
1
8
1
1
………..
………..
Data Byte High
A
8
1
PEC
A
8
1
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 20 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
8.4.5.
8.4.5.8.4.5.
8.4.5. Commands
CommandsCommands
Commands
RAM and EEPROM can be read both with 32x16 sizes. If the RAM is read, the data are divided by two, due to a sign bit in
RAM (for example, T
O1
- RAM address 0x07 will sweep between 0x27AD to 0x7FFF as the object temperature changes from -
70.01°C…+382.19°C). The MSB read from RAM is an error flag (active high) for the linearized temperatures (T
O1
,
T
O2
and T
a
).
The MSB for the raw data (e.g. IR sensor1 data) is a sign bit (sign and magnitude format). A write of 0x0000 must be done
prior to writing in EEPROM in order to erase the EEPROM cell content. Refer to EEPROM detailed description for factory
calibration EEPROM locations that need to be kept unaltered.
Opcode
Command
000x
xxxx*
RAM Access
001x xxxx*
EEPROM Access
1111_0000**
Read Flags
1111_1111
Enter SLEEP mode
Table 11: SMBus commands
Note*: The xxxxx represent the 5 LSBits of the memory map address to be read / written.
Note**: Behaves like read command. The MLX90614 returns PEC after 16 bits data of which only 4 are meaningful and if the
MD wants it, it can stop the communication after the first byte. The difference between read and read flags is that the latter
does not have a repeated start bit.
Flags read are:
Data[7] - EEBUSY - the previous write/erase EEPROM access is still in progress. High active.
Data[6] - Unused
Data[5] - EE_DEAD - EEPROM double error has occurred. High active.
Data[4] - INIT - POR initialization routine is still ongoing. Low active.
Data[3] - Not implemented.
Data[2...0] and Data[8...15] - All zeros.
Flag read is a diagnostic feature. The MLX90614 can be used regardless of these flags.
For details and examples for SMBus communication with the MLX90614 check the www.melexis.com
8.4.6.
8.4.6.8.4.6.
8.4.6. SMBus communication examples
SMBus communication examplesSMBus communication examples
SMBus communication examples
Figure 8: Read word format (SA=0x5A, read RAM=0x07, result=0x3AD2, PEC=0x30)
Figure 9: Write word format (SA=0x5A, write EEPROM=0x02, data=0xC807, PEC=0x48)
SCL
SDA
1 0 1 1 0 1 0 0A 0 0 0 0 1 1 1 AS S 0 1 1 0 1 0 A1 A A P
SA_W = 0xB4 Command = 0x07
RW 1 0 1 0 0 11 0 0 1 1 1 0 10 0 0 1 1 0 0 00 0 A
LSByte = 0xD2 MSByte = 0x3A PEC = 0x30SA_R = 0xB5
SCL
SDA
1 0 1 1 0 1 0 0A 0 1 0 0 0 1 0 AS 0 0 0 0 1 1 A0 A A P
Command = 0x22
1W 1 0 0 1 0 01 0 1 0 0 1 0 00 0
MSByte = 0xC8 PEC = 0x48LSByte = 0x07
SA_W = 0xB4
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 21 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
8.4.7.
8.4.7.8.4.7.
8.4.7. Timing specification
Timing specificationTiming specification
Timing specification
The MLX90614 meets all the timing specifications of the SMBus [1]. The maximum frequency of the MLX90614 SMBus is 100
KHz and the minimum is 10 KHz.
The specific timings in MLX90614’s SMBus are:
SMBus Request (t
REQ
) is the time that the SCL should be forced low in order to switch MLX90614 from PWM mode to SMBus
mode – at least 1.44ms;
Timeout L is the maximum allowed time for SCL to be low during communication. After this time the MLX90614 will reset its
communication block and will be ready for new communication – not more than 27ms;
Timeout H is the maximum allowed time for SCL to be high during communication.
After this time MLX90614 will reset its
communication block assuming that the bus is idle (according to the SMBus specification) – not more than 45μs.
Tsuac(SD) is the time after the eighth falling edge of SCL that MLX90614 will force PWM / SDA low to acknowledge the last
received byte – not more than 2.5μs.
Thdac(SD) is the time after the ninth falling edge of SCL that MLX90614 will release the PWM / SDA (so the MD can continue
with the communication) – not more than 1.5μs.
Tsuac(MD) is the time after the eighth falling edge of SCL that MLX90614 will release PWM / SDA (so that the MD can
acknowledge the last received byte) – not more than 1,5μs.
Thdac(MD) is the time after the ninth falling edge of SCL that MLX90614 will take control of the PWM / SDA (so it can
continue with the next byte to transmit) – not more than 1.5μs.
The indexes MD and SD for the latest timings are used – MD when the master device is making acknowledge; SD when the
slave device is making acknowledge. For other timings see [1].
Figure 10: SMBus timing specification and definition
SCL
SDA
Timeout_L
> 27ms
Timeout_H
> 45µs
1 2 3 4 5 6 7 8 9
1 0 1 0 1 0 1 1 ACK
Tsuac Thdac
MD < 1.5µs
SD < 2.5µs
MD < 1.5µs
SD < 1.5µs
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 22 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
8.4.8.
8.4.8.8.4.8.
8.4.8. Sleep Mode
Sleep ModeSleep Mode
Sleep Mode
The MLX90614 can enter in Sleep Mode via the command “Enter SLEEP mode” sent via the SMBus interface. This mode is
not available for the 5V supply version. There are two ways to put MLX90614 into power-up default mode:
- POR
- By Wake up request SCL pin high and then PWM/SDA pin low for at least t
DDQ
> 33ms
If EEPROM is configured for PWM (EN_PWM is high), the PWM interface will be selected after awakening and if PWM
control [2], PPODB is 1 the MLX90614 will output a PWM pulse train with push-pull output.
NOTE: In order to limit the current consumption to the typical 2.5μA Melexis recommends that the SCL pin is kept low during
sleep as there is leakage current trough the internal synthesized zener diode connected to SCL pin. This may be achieved by
configuring the MD driver of SCL pin as Push-Pull and not having Pull-Up resistor connected on SCL line.
8.4.8.1.
8.4.8.1.8.4.8.1.
8.4.8.1. Enter Sleep Mode
Enter Sleep ModeEnter Sleep Mode
Enter Sleep Mode
Figure 11: Enter sleep mode command (SA = 0x5A, Command = 0xFF, PEC = 0xE8)
8.4.8.2.
8.4.8.2.8.4.8.2.
8.4.8.2. Exit from Sleep Mode (Wake up request)
Exit from Sleep Mode (Wake up request)Exit from Sleep Mode (Wake up request)
Exit from Sleep Mode (Wake up request)
Figure 12: Exit Sleep Mode
After wake up the first data is available after 0.25 seconds (typ). On-chip IIR filter is skipped for the very first measurement.
All measurements afterwards pass the embedded digital filtering as configured in EEPROM. Details on embedded filtering
are available in application note “Understanding MLX90614 on-chip digital signal filters”, available from www.melexis.com
SCL
SDA
1 0 1 1 0 1 0 1A 1 1 1 1 1 1 1 AS 1 1 0 1 0 0 A1 P
Command = 0xFF
0W
PEC = 0xE8
SA_W = 0xB4
Normal operation mode Sleep mode
SDA
SCL > 33ms
Sleep mode Normal mode
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 23 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
8.4.9.
8.4.9.8.4.9.
8.4.9. MLX90614 SMBus specific remarks
MLX90614 SMBus specific remarksMLX90614 SMBus specific remarks
MLX90614 SMBus specific remarks
The auxiliary functions of the SCL pin (zener diode) add undershoot to the clock pulse (5V devices only) as shown in the
picture below (see Figure 13). This undershoot is caused by the transient response of the on-chip synthesized Zener diode.
Typical duration of undershoot is approximately 15μs. An increased reactance of the SCL line is likely to increase this effect.
Undershoot does not affect the recognition of the SCL rising edge by the MLX90914, but may affect proper operation of non-
MLX90614 slaves on the same bus.
Figure 13: Undershoot of SCL line due to on chip synthesized Zener diode (5V versions only)
Continuous SMBus readings can introduce and error. As the SCL line inside TO39 package is passing relatively close to the
sensor input and error signal is induced to the sensor output. The manifestation of the problem is wrong temperature
readings. This is especially valid for narrow FOV devices. Possible solution is to keep SDA and SCL line quiet for period longer
than refresh rate and settling time defined by internal settings of MLX90614 prior reading the temperature or switch to
PWM signal and completely disconnect from SDA and SCL line.
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 24 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
8.5.
8.5.8.5.
8.5. PWM
PWMPWM
PWM
The MLX90614 can be read via PWM or SMBus compatible interface. Selection of PWM output is done in EEPROM
configuration (factory default is SMBus). PWM output has two programmable formats, single and dual data transmission,
providing single wire reading of two temperatures (dual zone object or object and ambient). The PWM period is derived
from the on-chip oscillator and is programmable.
Config Register[5:4] PWM1 data PWM2 data Tmin,1 Tmax,1 Tmin,2 Tmax,2
00 T
A
T
O
1
T
A_r
ange
,L T
A_r
ange
,H T
O
_MIN
T
O_MAX
01 T
A
T
O
2
T
A_ra
nge
,L T
A_r
ange
,H T
O
_MIN
T
O_MAX
11 T
O
1
T
O
2
T
O
_MIN
T
O
_MAX
T
O
_MIN
T
O_MAX
10*
T
O2
Undefined
T
O_MIN
T
O_MAX
N.A.
N.A.
Table 12: PWM configuration table
Note: Serial data functions (2-wire / PWM) are multiplexed with a thermal relay function (described in the “Thermal
relay” section).
* Not recommended for extended PWM format operation
Figure 14: PWM timing single (above) and extended PWM (bellow)
PWM type t1 t2 t3 t4 t5 t6 t7 t8
Single 1/8 – high 4/8 - var 2/8 1/8 – low NA NA NA NA
Extended - S1 1/16 - high 4/16 - var 2/16 1/16 - low 1/16 - low 4/16 – low 2/16 - low 1/16 - low
Extended - S2 1/16 - high 4/16 - high 2/16 - high 1/16 - high 1/16 - high 4/16 - var 2/16 1/16 - low
Table 13: PWM timing
t1 t2
t3
t4
FE
Valid data band
Error band
Start Stop
0
T
5
8
T
1
8T
13
16 T
7
8T
t1 t2
t3
t4
FE
Sensor 1
Error band
Start Stop
0
T
1
16 TT
5
16 T
7
16 T
8
16
Valid data band
t5 t6
Sensor 1
t7
FE
Error band
Sensor 2
Sensor 2
Valid data band
t8
T
9
16 T
13
16 T
15
16
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 25 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
8.5.1.
8.5.1.8.5.1.
8.5.1. Single PWM format
Single PWM formatSingle PWM format
Single PWM format
In single PWM output mode the settings for PWM1 data only are used. The temperature reading can be calculated from the
signal timing as:
( )
MINOMINOMAXOOUT
TTT
T
t
T
___
2
2+
×=
where Tmin and Tmax are the corresponding rescale coefficients in EEPROM for the selected temperature output (Ta, object
temperature range is valid for both Tobj1 and Tobj2 as specified in the previous table) and T is the PWM period. Tout is T
O1
,
T
O2
or T
a
according to Config Register [5:4] settings.
The different time intervals t
1
…t
4
have following meaning:
t
1
: Start buffer. During this time the signal is always high. t
1
= 0.125s x T (where T is the PWM period, please refer to
Figure 14).
t
2
: Valid Data Output Band, 0…1/2T. PWM output data resolution is 10 bit.
t
3
: Error band – information for fatal error in EEPROM (double error detected, not correctable).
t
3
= 0.25s x T. Therefore a PWM pulse train with a duty cycle of 0.875 will indicate a fatal error in EEPROM (for single PWM
format). FE means Fatal Error.
Example:
Figure 15: PWM example single mode
CT
MINO
°= 0
_
( )
( )
3602731515.273100010,
__
ABxdTxEEPROMT
MINOMINO
==+×=
CT
MAXO
°= 50
_
( )
( )
BExdTxEEPROMT
MAXOMAXO
3703231515.273100000,
__
==+×=
Captured PWM period is T = 1004μs
Captured high duration is t = 392 μs
Calculated duty cycle is:
3904.0
1004
392 === T
t
D
or
%04.39
The temperature is calculated as follows:
( ) ( )
CT
O
°=××=+××= 54.26502654.020050125.03904.02
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 26 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
8.5.2.
8.5.2.8.5.2.
8.5.2. Extended PWM format
Extended PWM formatExtended PWM format
Extended PWM format
The PWM format for extended PWM is shown in Figure 16. Note that with bits DUAL[5:1]>0x00 each period will be
outputted 2N+1 times, where N is the decimal value of the number written in DUAL[5:1] (DUAL[5:1] =PWM control &
clock [8:4] ), like shown on Figure 16.
Figure 16: Extended PWM format with DUAL [5:1] = 01h (2 repetitions for each data)
The temperature transmitted in Data 1 field can be calculated using the following equation:
( )
111
2
1
4
MINMINMAXOUT
TTT
T
t
T+
×=
For Data 2 field the equation is:
( )
222
5
2
4
MINMINMAXOUT
TTT
T
t
T+
×=
Time bands are: t
1
=0.0625 x T (Start1), t
3
=0.125 x T and t
4
=0.5625 x T (Start2 = Start1 + Valida_data1 + error_band1 + stop1 +
start2). As shown in Figure 13, in extended PWM format the period is twice the period for the single PWM format. All
equations provided herein are given for the single PWM period T. The EEPROM Error band signaling will be 43.75% duty
cycle for Data1 and 93.75% for Data2.
Note: EEPROM error signaling is implemented in automotive grade parts only.
Figure 17: Example: Extended PWM mode readings sensor 1 above and sensor 2 bellow
t3
t1 t2
Start
0
T
1
16 T
T
8
16 T
15
16
t=16.875ms
T=100ms (PWM = 10Hz)
t1 t2
Start
0
T
1
16 TT
8
16 T
15
16
t=73.125ms
T=100ms (PWM = 10Hz)
Extended PWM mode sensor 1
Extended PWM mode sensor 2
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 27 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
Example: (see Figure 17 above):
Configuration:
Sensor1 = Ta, Sensor2 = T
obj1
Config Reg[5:4] = 00b,
CT
MINA
°= 0
_
( )
( )
Cxd
T
EEPROMT
A
LRANGEA
30606875.59
64
2.38
100
min_
__
==
+
×=
CT
MAXA
°= 60
_
( )
( )
9901534375.153
64
2.38
100
max_
__
xd
T
EEPROMT
A
HRANGEA
==
+
×=
( )
{ }
CxTTxEEPROMT
LRANGEAHRANGEARANGEA
9930:030,
_____
==
CT
MINO
°= 0
_
( )
( )
3602731515.273100010,
min__
ABxdTxEEPROMT
OMINO
==+×=
CT
MAXO
°= 50
_
( )
( )
BExdTxEEPROMT
OMAXO
3703231515.273100000,
min__
==+×=
Captured high durations are:
Sensor 1 – t = 16.875ms at period T = 100ms thus the duty cycle is
16875.0
100
875.16
1
==
S
Duty
Sensor 2 – t = 73.125ms at period T = 100ms thus the duty cycle is
73125.0
100
125.73
2
==
S
Duty
The temperatures are calculated as follows:
( )
( )
MINAMINAMAXASA
TTTStartDutyT
___1
14 +××=
( ) ( )
CT
A
°=+××= 5.2500600625.016875.04
( )
( )
MINOMINOMAXOSO
TTTStartDutyT
___21
24 +××=
( ) ( )
CT
O
°=+××= 75.3300505625.073125.04
1
8.5.3.
8.5.3.8.5.3.
8.5.3. Customizing the temperature range for PWM output
Customizing the temperature range for PWM outputCustomizing the temperature range for PWM output
Customizing the temperature range for PWM output
The calculated ambient and object temperatures are stored in RAM with a resolution of 0.01°C (16 bit). The PWM operates
with a 10-bit word so the transmitted temperature is rescaled in order to fit in the desired range.
For this goal 2 cells in EEPROM are foreseen to store the desired range for To (To
min
and To
max
) and one for Ta (Ta
range
: the
8MSB are foreseen for Ta
max
and the 8LSB for Ta
min
).
Thus the output range for To can be programmed with an accuracy of 0.01°C, while the corresponding Ta range can be
programmed with an accuracy of 0.64°C.
The object data for PWM is rescaled according to the following equation:
1023
,
EEPROMEEPROMEEPROM
obj
MINMAX
obj
PWM
obj
PWM
MINRAM
PWM
TT
K
K
TT
T
=
=
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 28 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
The T
RAM
is the linearized Tobj, 16-bit (0x0000…0xFFFF, 0x0000 for -273.15°C and 0xFFFF for +382.2°C) and the result is a 10-
bit word, in which 0x000 corresponds to To
MIN ,
°C, 0x3FF corresponds to To
MAX
,°C and 1LSB corresponds to
1023
MINMAX
ToTo
,°C.
100×=
MINMIN
TT
EEPORM
LSB
100×=
MAXMAX
TT
EEPORM
LSB
The ambient data for PWM is rescaled according to the following equation:
ambient
EEPROM
ambient
PWM
MINRAM
PWM
K
TT
T
=
Where:
1023
EEPROMEEPROM
MINMAX
ambient
PWM
TT
K
=
The result is a 10-bit word, where 0x000 corresponds to -38.2°C (lowest Ta that can be read via PWM), 0x3FF corresponds to
125°C (highest Ta that can be read via PWM) and 1LSB corresponds to:
[ ]
C
TT
LSB
MINMAX
°
=,
1023
1
( )( )
64
100
2.38 ×=
MINMIN
TT EEPORM
LSB
( )( )
64
100
2.38 ×=
MAXMAX
TT EEPORM
LSB
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 29 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
8.6.
8.6.8.6.
8.6. Switching Between PWM / Thermal relay and SMBus communication
Switching Between PWM / Thermal relay and SMBus communicationSwitching Between PWM / Thermal relay and SMBus communication
Switching Between PWM / Thermal relay and SMBus communication
8.6.1.
8.6.1.8.6.1.
8.6.1. PWM is enabled
PWM is enabledPWM is enabled
PWM is enabled
The diagram below illustrates the way of switching to SMBus if PWM / Thermal Relay is enabled (factory programmed POR
default for MLX90614 is SMBus, PWM disabled). Note that the SCL pin needs to be kept high in order to use PWM.
Figure 18: Switching from PWM mode to SMBus
8.6.2.
8.6.2.8.6.2.
8.6.2. Request condition
Request conditionRequest condition
Request condition
Figure 19: Request (switch to SMBus) condition
If PWM / Thermal relay is enabled, the MLX90614’s SMBus Request condition is needed to disable PWM / Thermal relay and
reconfigure PWM/SDA pin before starting SMBus communication. Once PWM / Thermal relay is disabled, it can be only
enabled by switching the supply OFF ON or exit from Sleep Mode. The MLX90614’s SMBus request condition requires
forcing LOW the SCL pin for period longer than the request time (t
REQ
>1,44ms). The SDA line value is ignored and is
irrelevant in this case.
8.6.3.
8.6.3.8.6.3.
8.6.3. PWM is disabled
PWM is disabledPWM is disabled
PWM is disabled
If PWM is disabled by means of EEPROM the PWM / SDA pin is directly used for the SMBus after POR. Request condition
should not be sent in this case.
SCL
PWM/SDA
Start Stop
t
REQ
PWM mode SMBus mode
>1.44ms
SCL
SMBus Request
t
REQ
>1,44ms
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 30 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
8.7.
8.7.8.7.
8.7. Computation of ambient and object temperatures
Computation of ambient and object temperaturesComputation of ambient and object temperatures
Computation of ambient and object temperatures
The IR sensor consists of serial connected thermo-couples with cold junctions placed at thick chip substrate and hot
junctions, placed over thin membrane. The IR radiation absorbed from the membrane heats (or cools) it. The thermopile
output signal is:
( )
( )
44
,TaToAToTaV
ir
×=
Where To is the absolute object temperature (Kelvin), Ta is the sensor die absolute (Kelvin) temperature, and A is the overall
sensitivity.
An on board temperature sensor is needed to measure the chip temperature. After measurement of the output of both
sensors, the corresponding ambient and object temperatures can be calculated. These calculations are done by the internal
DSP, which produces digital outputs, linearly proportional to measured temperatures.
8.7.1.
8.7.1.8.7.1.
8.7.1. Ambient temperature Ta
Ambient temperature TaAmbient temperature Ta
Ambient temperature Ta
The Sensor die temperature is measured with a PTAT element. All the sensors conditioning and data processing is handled
on-chip and the linearized sensor die temperature Ta is available in memory.
The resolution of the calculated temperature is 0.02°C. The sensor is factory calibrated for the full automotive
range -40…+125°C. The linearized die temperature is available in RAM cell 0x06:
0x06=0x2DE4 (11748d) corresponds to -38.2°C (linearization output lower limit)
0x06=0x4DC4 (19908d) corresponds to +125°C. (linearization output higher limit)
The conversions from RAM contend to real Ta is easy using the following relation:
02.0][ ×=° TaregKTa
, or 0.02°K / LSB.
8.7.2.
8.7.2.8.7.2.
8.7.2. Object temperature To
Object temperature ToObject temperature To
Object temperature To
The result has a resolution of 0.02°C and is available in RAM. To is derived from RAM as:
02.0][ ×=° ToregKTo
, or 0.02°K / LSB.
Please note that 1LSB corresponds to 0.02°C and the MSB bit is error flag (if “1” then error).
Example:
1. 0x27AD -70.00˚C (no error)
2. 0x27AE -69.98˚C (no error)
3. 0x3AF7 28.75˚C (no error)
4. 0x3AF8 28.77˚C (no error)
5. 0x7FFF 382.19˚C (no error) - maximum possible value returned by MLX90614
6. 0x8XXX xxx.xx˚C (flag error)
The result is calculated by following expressions (valid for both To and Ta):
1. Convert it to decimal value i.e. 0x3AF7 = 15095d
2. Divide by 50 (or multiply by 0.02) i.e.
9.301
50
15095 =
K (result is in Kelvin)
3. Convert K -> °C i.e. 301.9 - 273.15 = 28.75°C
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 31 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
8.7.3.
8.7.3.8.7.3.
8.7.3. Calculation flow
Calculation flowCalculation flow
Calculation flow
The measurement, calculation and linearization are held by core, which executes a program form ROM.
After POR the chip is initialized with calibration data from EEPROM. During this phase the number of IR sensors is selected
and it is decided which temperature sensor will be used. Measurements, compensation and linearization routines run in a
closed loop afterwards.
Processing ambient temperature includes:
Offset measurement with fixed length FIR filter
Additional filtering with fixed length IIR filter. The result is stored into RAM as T
OS
Temperature sensor measurement using programmable length FIR *.
Offset compensation
Additional processing with programmable length IIR **. The result is stored into RAM as T
D
.
Calculation of the ambient temperature. The result is stored into RAM address 0x06 as T
A
Processing of the object temperature consists of three parts.
The first one is common for both IR sensors, the third part can be skipped if only one IR sensor is used.
IR offset:
Offset measurement with a fixed length FIR
Additional filtering with a fixed length IIR. The result is stored into RAM as IR
OS
.
Gain measurement with fixed length FIR filter
Offset compensation
Additional gain filtering with fixed length IIR, storing the result into RAM as IR
G
.
Gain compensation calculation, the result is stored into RAM as K
G
Object temperature:
IR1 sensor:
IR sensor measurement with programmable length FIR filter *.
Offset compensation
Gain compensation
Filtering with programmable length IIR filter**, storing the result into RAM address 0x04 as IR1
D
.
Calculation of the object temperature. The result is available in RAM address 0x07 as T
O1
.
IR2 sensor:
IR sensor measurement with programmable length FIR filter *.
Offset compensation
Gain compensation
Filtering with programmable length IIR filter**, storing the result into RAM address 0x05 as IR2
D
Calculation of the object temperature. The result is available in RAM address 0x08 as T
O2
PWM calculation:
Recalculate the data for PWM with 10 bit resolution
Load data into PWM module
Note*: The measurements with programmable filter length for FIR filter use the same EEPROM cells for N.
Note**: The IIR filter with programmable filter length uses the same EEPROM cells for L.
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 32 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
Figure 20: Software flow
8.8.
8.8.8.8.
8.8. Thermal relay
Thermal relayThermal relay
Thermal relay
The MLX90614 can be configured as a thermo relay with programmable threshold and hysteresis on the PWM/SDA pin. The
input for the comparator unit of the relay is the object temperature from sensor 1
The output of the MLX90614 is NOT a relay driver but a logical output which should be connected to a relay driver if
necessary.
The output driver is one and the same for PWM and Thermal relay.
In order to configure the MLX90614 to work as thermal relay two conditions must be met:
o Set bit TRPWMB high at address 0x02 in EEPROM
o Enable PWM output i.e. EN_PWM is set high
The PWM / SDA pin can be programmed as a push-pull or open drain NMOS (via bit PPODB in EEPROM PWMCTRL), which
can trigger an external device. The temperature threshold data is determined by EEPROM at address 0x21 (To
min
) and the
hysteresis at address 0x020 (To
max
).
The logical state of the PWM/SDA pin is as follows:
PWM / SDA pin is high if
hysteresisthresholdT
O
+
1
PWM / SDA pin is low if
hysteresisthresholdT
O
1
Figure 21: Thermal relay:PWM pin versus Tobj
Initialization
T
A
Offset meas
OS
Ta
= meas(N
Tos
)
filtering
T
OS
= IIR(L
Tos
,OS
Ta
)
T
A
meas
T
DATA
= meas(N
Ta
)
Offset comp
T
DATAcomp
= T
DATA
-T
OS
filtering
T
D
= IIR(L
Ta
,T
DATAcomp
)
T
A
calculation
T
A
IR Offset meas
OS
IR
= meas(N
IRos
)
filtering
IR
OS
= IIR(L
IRos
,OS
IR
)
IR1 meas
IR1
D
= meas(N
IR
)
Offset comp
IR1
Dcomp
= IR1
D
- IR
OS
filtering
IR1
D
= IIR(L
IR
,IR1
Dg
)
T
OBJ1
calculation
Gain drift
IR
Gm
= meas(N
IRg
)
Offset comp
IR
Gcomp
= IR
Gm
- IR
OS
filtering
IR
G
= IIR(L
G
,IR
Gcomp
)
K
G
calculation
IR offset
Gain comp
IR1
Dg
= IR1
Dcomp
*K
G
IR2 meas
IR2
D
= meas(N
IR
)
Offset comp
IR2
Dcomp
= IR2
D
- IR
OS
filtering
IR2
D
= IIR(L
IR
,IR2
Dg
)
T
OBJ2
calculation
Gain comp
IR2
Dg
= IR2
Dcomp
*K
G
T
OBJ1
T
OBJ2
PWM
calculation
Load PWM
registers
1
123
23
threshold
hysteresis hysteresis
T
“0”
“1”
MLX90614 family
Single and Dual Zone
Infra Red Thermometer in TO-39
Page 33 of 57
REVISION 11 - 20 NOVEMBER 2018
3901090614
The MLX90614 preserves its normal operation when configured as a thermal relay (PWM configuration and specification
applies as a general rule also for the thermal relay) and therefore it can be read using the SMBus (entering the SMBus mode
from both PWM and thermal relay configuration is the same).
For example, the MLX90614 can generate a wake-up alert for a system upon reaching a certain temperature and then be
read as a thermometer. Reset conditions (enter and exit Sleep, for example) will be needed in order to return to the thermal
relay configuration.
Example:
CThreshold °= 5
( ) ( )
7602781515.273100010, CAxdThresholdxEEPROM ==+×=
CHysteresis °= 1
( )
00640100100000, xdHysteresisxEEPROM ==×=
Smallest possible hysteresis is 0,01°C or (EEPROM, 0x00 = 0x0001)
PWM / SDA pin will be set low at object temperature below 4°C
PWM / SDA pin will be set high at object temperature higher that 6°C
9. Unique Features
The MLX90614 is a ready-to use low-cost non-contact thermometer provided from Melexis with output data
linearly dependent on the object temperature with high accuracy and extended resolution.
The high thermal stability of the MLX90614-xCx make this part highly suited in applications where secondary
heat sources can heat up the sensor. These sensors also have a very short stabilization time compared to
other types of thermopile sensors, which is of importance if one needs an accurate measurement in conditions
where the ambient temperature can change quickly.
The MLX90614 supports versatile customization to a very wide range of temperatures, power supplies and
refresh rates.
The user can program the internal object emissivity correction for objects with a low emissivity. An embedded
error checking and correction mechanism provides high memory reliability.
The sensors are housed in an industry standard TO39 package for both single- and dual-zone IR thermometers.
The thermometer is available in automotive grade and can use two different packages for wider applications’
coverage.
The low power consumption during operation and the low current draw during sleep mode make the
thermometer ideally suited for handheld mobile applications.
The digital sensor interface can be either a power-up-and-measur