INA138/168 Datasheet by Texas Instruments

l TEXAS INSTRUMENTS X E L ? Copynghl © 1999, Texas Insmmems |ncurpara|ed
IS
RS
V
IN+
Up To
60 V
3
4
VIN+
V
IN–
5 kΩ
5 kΩ
Load
V+
5
GND
2
OUT
1V = I R R
O S S L / 5 kΩ
Copyright © 1999, Texas Instruments Incorporated
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An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,
intellectual property matters and other important disclaimers. PRODUCTION DATA.
INA138
,
INA168
SBOS122E DECEMBER 1999REVISED DECEMBER 2017
INA1x8 High-Side Measurement Current Shunt Monitor
1
1 Features
1 Complete Unipolar High-Side Current
Measurement Circuit
Wide Supply and Common-Mode Range
INA138: 2.7 V to 36 V
INA168: 2.7 V to 60 V
Independent Supply and Input Common-Mode
Voltages
Single Resistor Gain Set
Low Quiescent Current (25 µA Typical)
Wide Temperature Range: –40°C to +125°C
5-Pin SOT-23 Package
2 Applications
Current Shunt Measurement:
Telephone, Computers
Portable and Battery-Backup Systems
Battery Chargers
Power Management
Cell Phones
Precision Current Source
3 Description
The INA138 and INA168 (INA1x8) are high-side,
unipolar, current shunt monitors. Wide input common-
mode voltage range, low quiescent current, and tiny
SOT-23 packaging enable use in a variety of
applications.
Input common-mode and power-supply voltages are
independent and can range from 2.7 V to 36 V for the
INA138 and 2.7 V to 60 V for the INA168. Quiescent
current is only 25 µA, which permits connecting the
power supply to either side of the current
measurement shunt with minimal error.
The device converts a differential input voltage to a
current output. This current is converted back to a
voltage with an external load resistor that sets any
gain from 1 to over 100. Although designed for
current shunt measurement, the circuit invites
creative applications in measurement and level
shifting.
Both the INA138 and INA168 are available in SOT23-
5 and are specified for the –40°C to 125°C
temperature range.
Device Information(1)
PART NUMBER PACKAGE BODY SIZE (NOM)
INA138 SOT-23 (5) 2.90 mm × 1.60 mm
INA168
(1) For all available packages, see the package option addendum
at the end of the datasheet.
Typical Application Circuit
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Table of Contents
1 Features.................................................................. 1
2 Applications ........................................................... 1
3 Description ............................................................. 1
4 Revision History..................................................... 2
5 Pin Configuration and Functions......................... 3
6 Specifications......................................................... 4
6.1 Absolute Maximum Ratings ...................................... 4
6.2 ESD Ratings ............................................................ 4
6.3 Recommended Operating Conditions....................... 4
6.4 Thermal Information ................................................. 5
6.5 Electrical Characteristics........................................... 5
6.6 Typical Characteristics.............................................. 6
7 Detailed Description.............................................. 8
7.1 Overview ................................................................... 8
7.2 Functional Block Diagram......................................... 8
7.3 Feature Description................................................... 9
7.4 Device Functional Modes.......................................... 9
8 Application and Implementation ........................ 10
8.1 Application Information............................................ 10
8.2 Typical Applications ............................................... 11
9 Power Supply Recommendations...................... 18
10 Layout................................................................... 18
10.1 Layout Guidelines ................................................. 18
10.2 Layout Example .................................................... 18
11 Device and Documentation Support ................. 19
11.1 Documentation Support ....................................... 19
11.2 Related Links ........................................................ 19
11.3 Receiving Notification of Documentation Updates 19
11.4 Community Resources.......................................... 19
11.5 Trademarks........................................................... 19
11.6 Electrostatic Discharge Caution............................ 19
11.7 Glossary................................................................ 19
12 Mechanical, Packaging, and Orderable
Information ........................................................... 20
4 Revision History
NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
Changes from Revision D (December 2014) to Revision E Page
Added reference design link to navigation bar at the top of the front page ........................................................................... 1
Changed body size from 18.00 mm × 18.00 mm to 2.90 mm × 1.60 mm in Device Information table.................................. 1
Changed pin numbers in pin functions table to match pin configuration figure...................................................................... 3
Changed Absolute Maximum Ratings table for clarity; no values were changed ................................................................. 4
Changed Recommended Operating Conditions table; moved some content from Electrical Characteristics table, but
no values changed ................................................................................................................................................................. 4
Changed all values in Thermal Information table................................................................................................................... 5
Changed Electrical Characteristics table; reformatted for clarity; moved some content to Recommended Operating
Conditions table, and deleted duplicate content..................................................................................................................... 5
Changed common-mode rejection test conditions to better highlight each device in Electrical Characteristics table .......... 5
Changed offset voltage vs temperature to offset voltage drift in Electrical Characteristics table........................................... 5
Changed offset voltage vs power supply test conditions to better highlight each device in Electrical Characteristics table. 5
Changed reference in text from Figure 10 to Figure 11 in last paragraph of Selecting the Shunt Resistor and RLsection 12
Changes from Revision C (November 2005) to Revision D Page
Added ESD Ratings table, Feature Description section, Device Functional Modes,Application and Implementation
section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and
Mechanical, Packaging, and Orderable Information section. ................................................................................................ 1
l TEXAS INSTRUMENTS flflfl
1OUT
2GND
3VIN+ 4 VIN±
5 V+
Not to scale
3
INA138
,
INA168
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5 Pin Configuration and Functions
DBV Package
5-Pin SOT-23
Top View
Pin Functions
PIN I/O DESCRIPTION
NO. NAME
1 OUT O Output current
2 GND — Ground
3 VIN+ I Positive input voltage
4 VIN– I Negative input voltage
5 V+ I Power supply voltage
l TEXAS INSTRUMENTS
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(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings
only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended
Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.
(2) The input voltage at any pin may exceed the voltage shown if the current at that pin is limited to 10 mA.
6 Specifications
6.1 Absolute Maximum Ratings
over operating free-air temperature range (unless otherwise noted) (1)
MIN MAX UNIT
Voltage
Supply, V+ INA138 –0.3 60
V
INA168 –0.3 75
Analog input, VIN+, VIN–
INA138 Common mode(2) –0.3 60
Sense voltage, VSENSE = (VIN+ – VIN–) –40 2
INA168 Common mode(2) –0.3 75
Sense voltage, VSENSE = (VIN+ – VIN–) –40 2
Analog output, OUT pin(2) –0.3 40
Current Input current into any pin 10 mA
Temperature
Operating, TA–55 150
°CJunction, TJ150
Storage, Tstg –65 150
(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.
(2) JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process.
6.2 ESD Ratings
VALUE UNIT
V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1) ±1000 V
Charged-device model (CDM), per JEDEC specification JESD22-C101(2) ±500
6.3 Recommended Operating Conditions
over operating free-air temperature range (unless otherwise noted)
MIN NOM MAX UNIT
INA138
V+ Supply voltage 2.7 5 36 V
VSENSE Full-scale sense voltage (VIN+ – VIN–) 100 500 mV
Common-mode voltage 2.7 12 36 V
TAOperating temperature –40 25 125 °C
INA168
V+ Supply voltage 2.7 5 60 V
VSENSE Full-scale sense voltage (VIN+ – VIN–) 100 500 mV
Common-mode voltage 2.7 12 60 V
TAOperating temperature –40 25 125 °C
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(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application
report.
6.4 Thermal Information
THERMAL METRIC(1)
INA1x8
UNITDBV
5 PINS
RθJA Junction-to-ambient thermal resistance 168.3 °C/W
RθJC(top) Junction-to-case (top) thermal resistance 73.8 °C/W
RθJB Junction-to-board thermal resistance 28.1 °C/W
ψJT Junction-to-top characterization parameter 2.5 °C/W
ψJB Junction-to-board characterization parameter 27.6 °C/W
(1) Defined as the amount of input voltage, VSENSE, to drive the output to zero.
6.5 Electrical Characteristics
all other characteristics at TA= +25°C, VS= 5 V, VIN+ = 12 V, and ROUT = 125 kΩ(unless otherwise noted)
PARAMETER TEST CONDITIONS INA1x8 UNIT
MIN TYP MAX
INPUT
Common-mode rejection VSENSE = 50 mV INA138, VIN+ = 2.7 V to 36 V 100 120 dB
INA168, VIN+ = 2.7 V to 60 V 100 120
Offset voltage(1) TA= 25°C ±0.2 ±1 mV
TA= –40°C to +125°C ±2
Offset voltage drift(1) TA= –40°C to +125°C 1 µV/°C
Offset voltage vs power supply, V+ VSENSE = 50 mV INA138, V+ = 2.7 V to 36 V 0.1 10 µV/V
INA168, V+ = 2.7 V to 60 V 0.1 10
Input bias current TA= 25°C 2 µA
TA= –40°C to +125°C, INA138 10
OUTPUT
Transconductance VSENSE = 10 mV to 150 mV, TA= 25°C 198 200 202 µA/V
VSENSE = 100 mV, TA= –40°C to +125°C 196 204 µA/V
Transconductance drift TA= –40°C to +125°C 10 nA/°C
Nonlinearity error VSENSE = 10 mV to 150 mV ±0.01% ±0.1%
Total output error VSENSE = 100 mV TA= 25°C ±0.5% ±2%
TA= –40°C to +125°C ±2.5%
Output impedance 1 || 5 G|| pF
Voltage output swing To power supply voltage, V+ (V+) – 0.8 (V+) – 1.0 V
To common-mode voltage, VCM VCM – 0.5 VCM – 0.8 V
FREQUENCY RESPONSE
Bandwidth ROUT = 5 k800 kHz
ROUT = 125 k32 kHz
Settling time To 0.1% 5-V step, ROUT = 5 k1.8 µs
5-V step, ROUT = 125 k30 µs
NOISE
Output-current noise density 9 pA/Hz
Total output-current noise BW = 100 kHz 3 nA RMS
POWER SUPPLY
Quiescent current VSENSE = 0 V,
IO= 0 mA
TA= 25°C 25 45 µA
TA= –40°C to +125°C 60 µA
l TEXAS INSTRUMENTS Gam(am M 120 \ \ \ M 100x 140 EEEEEEEEEEEE===;§\ 2w
Total Output Error (%)
2
Output error is essentially
independent of both
1V+ supply voltage and
input common-mode voltage.
0G = 1
G =
10
–1 G = 25
–2
0 10 20 30 40 50
Power-Supply Voltage (V)
60 70
Power-Supply Rejection (dB)
140
120
100
80
60
40
G = 1
G = 100
G = 10
20
1 10 100 1k 10k 100k
Frequency (Hz)
Total Output Error (%)
–10
55°C
+25°C
+150°C
VIN = (VIN+ – VIN–)
–15
025 50 75 100 125
VIN (mV)
150 200
–5
0
5
Common-Mode Rejection (dB)
120
100
80
60
40
G =
100
G = 10
G = 1
20
0
0.1 1 10 100 1k 10k
Frequency (Hz)
100k
Gain (dB)
40
30
R =
L50kΩ
20
10
R =
L5kΩ
0
R =
L500kΩ
–10
–20
C =
L10nF C =
L1nF C =
L100pF
100 1k 10k 100k 1M 10M
Frequency (Hz)
6
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,
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6.6 Typical Characteristics
At TA= +25°C, V+ = 5 V, VIN+ = 12 V, and RL= 125 kΩ, unless otherwise noted.
Figure 1. Gain vs Frequency Figure 2. Common-Mode Rejection vs Frequency
Figure 3. Power-Supply Rejection vs Frequency Figure 4. Total Output Error vs VIN
Figure 5. Total Output Error vs Power-Supply Voltage Figure 6. Quiescent Current vs Power-Supply Voltage
l TEXAS INSTRUMENTS 200 WW I, , ‘ e : 1 ‘1 G : 25 I V/dlv 100 mV ' ‘ ‘ 7 7 ,, u v , 50 mV/dw 100 mV ,, _ ‘ ,,,,,, G : ‘s ‘ G : 1° \ 500 mV/div 0 mV ‘ u v W ~77 mus/div IONS/aw
m
m
7
INA138
,
INA168
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Typical Characteristics (continued)
At TA= +25°C, V+ = 5 V, VIN+ = 12 V, and RL= 125 kΩ, unless otherwise noted.
Figure 7. Step Response Figure 8. Step Response
l TEXAS INSTRUMENTS va~ vwi v~ Copyngh|© 2mm Texas \nslrumems \ncarpma‘eu
Copyright © 2014, Texas Instruments Incorporated
VIN+ VIN– V+
OUT
GND
8
INA138
,
INA168
SBOS122E DECEMBER 1999REVISED DECEMBER 2017
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7 Detailed Description
7.1 Overview
The INA138 and INA168 devices (INA1x8) are comprised of a high voltage, precision operational amplifier,
precision thin film resistors trimmed in production to an absolute tolerance and a low noise output transistor. The
INA1x8 devices can be powered from a single power supply and their input voltages can exceed the power
supply voltage. The INA1x8 devices are ideal for measuring small differential voltages, such as those generated
across a shunt resistor, in the presence of large common-mode voltages. Refer to Functional Block Diagram
which illustrates the functional components within both INA1x8 devices.
7.2 Functional Block Diagram
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7.3 Feature Description
7.3.1 Output Voltage Range
The output of the INA1x8 device is a current that is converted to a voltage by the load resistor, RL. The output
current remains accurate within the compliance voltage range of the output circuitry. The shunt voltage and the
input common-mode and power-supply voltages limit the maximum possible output swing. The maximum output
voltage (Vout max) compliance is limited by either Equation 1 or Equation 2, whichever is lower:
Vout max = (V+) – 0.7 V – (VIN+ – VIN–) (1)
or
Vout max = VIN– – 0.5 V (2)
7.3.2 Bandwidth
Measurement bandwidth is affected by the value of the load resistor, RL. High gain produced by high values of
RLwill yield a narrower measurement bandwidth (see Typical Characteristics). For widest possible bandwidth,
keep the capacitive load on the output to a minimum. Reduction in bandwidth due to capacitive load is shown in
the Typical Characteristics.
If bandwidth limiting (filtering) is desired, a capacitor can be added to the output (see Figure 12). This will not
cause instability.
7.4 Device Functional Modes
For proper operation the INA1x8 devices must operate within their specified limits. Operating either device
outside of their specified power supply voltage range or their specified common-mode range will result in
unexpected behavior and is not recommended. Additionally operating the output beyond their specified limits with
respect to power supply voltage and input common-mode voltage will also produce unexpected results. Refer to
Electrical Characteristics for the device specifications.
l TEXAS INSTRUMENTS
VOLTAGE GAIN EXACT R ( )
LΩNEAREST 1% R ( )
LΩ
1
2
5
10
20
50
100
5k
10k
25k
50k
100k
250k
500k
4.99k
10k
24.9k
49.9k
100k
249k
499k
I
V
P
Load Power
Supply
Shunt
RSS
V+ power can be common or
independent of load supply. V+
VIN+
V
IN–
3
4
Load
RG1
5 kΩ
RG2
5 kΩ
5
Q1
INA138
2
OUT
1
I
0
+
R V
L O
2.7 V to 36 V(1)
2.7 V (V+) 36 V(1)
Copyright © 1999, Texas Instruments Incorporated
10
INA138
,
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8 Application and Implementation
NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
8.1.1 Operation
Figure 9 illustrates the basic circuit diagram for both the INA138 and INA168 devices. Load current ISis drawn
from supply VSthrough shunt resistor RS. The voltage drop in shunt resistor VSis forced across RG1 by the
internal op amp, causing current to flow into the collector of Q1. External resistor RLconverts the output current
to a voltage, VOUT, at the OUT pin. The transfer function for the INA138 device is:
IO= gm(VIN+ – VIN–) (3)
where gm= 200 µA/V.
In the circuit of Figure 9, the input voltage, (VIN+ – VIN–), is equal to IS× RSand the output voltage, VOUT, is equal
to IO× RL. The transconductance, gm, of the INA138 device is 200 µA/V. The complete transfer function for the
current measurement amplifier in this application is:
VOUT = (IS) (RS) (200 µA/V) (RL) (4)
The maximum differential input voltage for accurate measurements is 0.5 V, which produces a 100-µA output
current. A differential input voltage of up to 2 V will not cause damage. Differential measurements (pins 3 and 4)
must be unipolar with a more-positive voltage applied to pin 3. If a more-negative voltage is applied to pin 3, the
output current, IO, will be zero, but it will not cause damage.
(1) Maximum VPand V+ voltage is 60 V with INA168.
Figure 9. Basic Circuit Connections
l TEXAS INSTRUMENTS
+
RL
OPA340
ADC
RS
C
IS
Buffer amplifier
drives ADC without
affecting gain
INA138
or
INA168
VIN+ VIN-
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8.2 Typical Applications
The INA1x8 devices are designed for current shunt measurement circuits, as shown in Figure 9, but basic device
function is useful in a wide range of circuitry. A creative engineer will find many unforeseen uses in measurement
and level-shifting circuits. A few ideas are illustrated in Figure 10 through Figure 18.
8.2.1 Buffering Output to Drive an ADC
Figure 10. Buffering Output to Drive an ADC
8.2.1.1 Design Requirements
Digitize the output of the INA1x8 devices using a 1-MSPS analog-to-digital converter (ADC).
8.2.1.2 Detailed Design Procedure
8.2.1.2.1 Selecting the Shunt Resistor and RL
In Figure 9 the value chosen for the shunt resistor depends on the application and is a compromise between
small-signal accuracy and maximum permissible voltage loss in the measurement line. High values of shunt
resistor provide better accuracy at lower currents by minimizing the effects of offset, while low values of shunt
resistor minimize voltage loss in the supply line. For most applications, best performance is attained with a shunt
resistor value that provides a full-scale shunt voltage range of 50 mV to 100 mV. Maximum input voltage for
accurate measurements is 500 mV.
The load resistor, RL, is chosen to provide the desired full-scale output voltage. The output impedance of the
INA1x8 OUT terminal is very high which permits using values of RLup to 500 kΩwith excellent accuracy. The
input impedance of any additional circuitry at the output should be much higher than the value of RLto avoid
degrading accuracy.
Some analog-to-digital converters (ADCs) have input impedances that significantly affect measurement gain. The
input impedance of the ADC can be included as part of the effective RLif its input can be modeled as a resistor
to ground. Alternatively, an op amp can be used to buffer the ADC input. The INA1x8 are current output devices,
and as such have an inherently large output impedance. The output currents from the amplifier are converted to
an output voltage via the load resistor, RL, connected from the amplifier output to ground. The ratio of the load
resistor value to that of the internal resistor value determines the voltage gain of the system.
In many applications digitizing the output of the INA1x8 device is required, and can be accomplished by
connecting the output of the amplifier to an ADC. It is very common for an ADC to have a dynamic input
impedance. If the INA1x8 output is connected directly to an ADC input, the input impedance of the ADC is
effectively connected in parallel with the gain setting resistor RL. This parallel impedance combination will affect
the gain of the system and the impact on the gain is difficult to estimate accurately. A simple solution that
eliminates the paralleling of impedances, simplifying the gain of the circuit is to place a buffer amplifier, such as
the OPA340, between the output of the INA138 or INA168 device and the input to the ADC.
l TEXAS INSTRUMENTS Tune
Time
Input to ADC (0.25 V/div)
with buffer
without Buffer
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Typical Applications (continued)
Figure 10 illustrates this concept. Notice that a low pass filter is placed between the OPA340 output and the input
to the ADC. The filter capacitor is required to provide any instantaneous demand for current required by the input
stage of the ADC. The filter resistor is required to isolate the OPA340 output from the filter capacitor to maintain
circuit stability. The values for the filter components will vary according to the operational amplifier used for the
buffer and the particular ADC selected. More information can be found regarding the design of the low pass filter
in the TI Precision Design , 16 bit 1MSPS Data Acquisition Reference Design for Single-Ended Multiplexed
Applications (TIPD173).
Figure 11 shows the expected results when driving an analog-to-digital converter at 1MSPS with and without
buffering the INA1x8 output. Without the buffer, the high impedance of the INA1x8 reacts with the input
capacitance and sample and hold (S/H) capacitance of the ADC, and does not allow the S/H to reach the correct
final value before it is reset and the next conversion starts. Adding the buffer amplifier significantly reduces the
output impedance driving the S/H and allows for higher conversion rates than can be achieved without adding
the buffer.
8.2.1.3 Application Curve
Figure 11. Driving an ADC With and Without a Buffer
l TEXAS INSTRUMENTS (3am (a5) 40 \ \ \ M
Gain (dB)
40
30
R =
L50kΩ
20
10
R =
L5kΩ
0
R =
L500kΩ
–10
–20
C =
L10nF C =
L1nF C =
L100pF
100 1k 10k 100k 1M 10M
Frequency (Hz)
3 4
INA138 f3dB =
f3dB
1
2 R CπL L
VO
RC
LL
13
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INA168
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Typical Applications (continued)
8.2.2 Output Filter
Figure 12. Output Filter
8.2.2.1 Design Requirements
Filter the output of the INA1x8 devices.
8.2.2.2 Detailed Design Procedure
A low-pass filter can be formed at the output of the INA1x8 devices simply by placing a capacitor of the desired
value in parallel with the load resistor. First determine the value of the load resistor needed to achieve the
desired gain. Refer to the table in Figure 9. Next, determine the capacitor value that will result in the desired
cutoff frequency according to the equation shown in Figure 12.Figure 13 illustrates various combinations of gain
settings (determined by RL) and filter capacitors.
8.2.2.3 Application Curve
Figure 13. Gain vs Frequency
‘5‘ TEXAS INSTRUMENTS
Gain Set by RL
Output Offset = (100 µA)(RL)
(independent of V+)
b) Using current source.
Gain Set by R1 || R2
a) Using resistor divider.
R1 + R2
Output Offset = (VR)R2
R1
1
VR
INA138
3 4
VO
R2
REF200
100 µA
INA138
3 4
1
V+
VO
RL
14
INA138
,
INA168
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Typical Applications (continued)
8.2.3 Offsetting the Output Voltage
For many applications using only a single power supply it may be required to level shift the output voltage away
from ground when there is no load current flowing in the shunt resistor. Level shifting the output of the INA1x8
devices is easily accomplished by one of two simple methods shown in Figure 14. The method on the left hand
side of Figure 14 illustrates a simple voltage divider method. This method is useful for applications that require
the output of the INA1x8 devices to remain centered with respect to the power supply at zero load current
through the shunt resistor. Using this method the gain is determine by the parallel combination of R1and R2
while the output offset is determined by the voltage divider ratio R1and R2. For applications that may require a
fixed value of output offset, independent of the power supply voltage, the current source method shown on the
right-hand side of Figure 14 is recommended. With this method a REF200 constant current source is used to
generate a constant output offset. Using his method the gain is determined by RLand the offset is determined by
the product of the value of the current source and RL.
Figure 14. Offsetting the Output Voltage
‘5‘ TEXAS INSTRUMENTS 3 G) :V V: g ‘ 4—!
+
5 k5 k
VIN+ VIN±
OUT
V+
GND
+
5 k5 k
VIN+VIN±
OUT
V+
GND
100 m
+
INA138
or
INA168
INA138
or
INA168
1N4148 1N4148
10 k10 k
100 k
Sign
Output
TLV3201
+5 V
+5 V
Bus
Voltage Load
Current
RSH
±1 A
Load Curent
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,
INA168
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SBOS122E DECEMBER 1999REVISED DECEMBER 2017
Product Folder Links: INA138 INA168
Submit Documentation FeedbackCopyright © 1999–2017, Texas Instruments Incorporated
Typical Applications (continued)
8.2.4 Bipolar Current Measurement
The INA1x8 devices can be configured as shown in Figure 15 in applications where measuring current bi-
directionally is required. Two INA devices are required connecting their inputs across the shunt resistor as shown
in Figure 15. A comparator, such as the TLV3201, is used to detect the polarity of the load current. The
magnitude of the load current is monitored across the resistor connected between ground and the connection
labeled Output. In this example the 100-kΩresistor results in a gain of 20 V/V. The 10-kΩresistors connected in
series with the INA1x8 output current are used to develop a voltage across the comparator inputs. Two diodes
are required to prevent current flow into the INA1x8 output, as only one device at a time is providing current to
the Output connection of the circuit. The circuit functionality is illustrated in Figure 16.
Figure 15. Bipolar Current Measurement
l TEXAS INSTRUMENTS Twme
V+ RS
4 3 34
+5V
+5V +5V REFOUT BUFIN BUFOUT
55
Digital
I/O
REF BUF
INA138
12
INA138
21MUX PGIA
12-Bit A/D
Converter
RL
25kΩ
A/D converter programmed for differential input.
RL
25kΩ
Clock
Divider
Oscillator
ADS7870
Serial
I/O
Depending on polarity of current, one INA138 provides
an output voltage, the output of the other is zero.
Time
Voltage
Load Current
Output
Sign
16
INA138
,
INA168
SBOS122E DECEMBER 1999REVISED DECEMBER 2017
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Product Folder Links: INA138 INA168
Submit Documentation Feedback Copyright © 1999–2017, Texas Instruments Incorporated
Typical Applications (continued)
Figure 16. Bipolar Current Measurements Results (arbitrary scale)
8.2.5 Bipolar Current Measurement Using Differential Input of ADC
The INA1x8 devices can be used with an ADC such as the ADS7870 programmed for differential mode
operation. Figure 17 illustrates this configuration. In this configuration the use of two INAs allows for bidirectional
current measurement. Depending upon the polarity of the current, one of the INAs provides an output voltage,
while the other output is zero. In this way the ADC reads the polarity of current directly, without the need for
additional circuitry.
Figure 17. Bipolar Current Measurement Using Differential Input of ADC
l TEXAS INSTRUMENTS
Other INA168s
––
INA168
V+
Digital I/O on the ADS7870 provides power to select
the desired INA168. Diodes prevent output current of
the on INA168 from flowing into the off INA168.
+5V
REFOUT BUFIN BUFOUT
INA168
V+
Digital
I/O
REF BUF
––
IN4148
MUX PGIA
12-Bit A/D
Converter
Clock
RDivider
LOscillator ADS7870
Serial
I/O
17
INA138
,
INA168
www.ti.com
SBOS122E DECEMBER 1999REVISED DECEMBER 2017
Product Folder Links: INA138 INA168
Submit Documentation FeedbackCopyright © 1999–2017, Texas Instruments Incorporated
Typical Applications (continued)
8.2.6 Multiplexed Measurement Using Logic Signal for Power
Multiple loads can be measured as illustrated in Figure 18. In this configuration each INA1x8 device is powered
by the digital I/O from the ADS7870. Multiplexing is achieved by switching on or off each the desired I/O.
Figure 18. Multiplexed Measurement Using Logic Signal for Power
l TEXAS INSTRUMENTS
OUT V+
VIN+ VIN-
PCB pad
0.1 µF
VIA to Ground Plane
Supply Voltage
Output
PCB pad
To Bus
Voltage To Load
RL
GND
RSHUNT
INA138
INA168
18
INA138
,
INA168
SBOS122E DECEMBER 1999REVISED DECEMBER 2017
www.ti.com
Product Folder Links: INA138 INA168
Submit Documentation Feedback Copyright © 1999–2017, Texas Instruments Incorporated
9 Power Supply Recommendations
The input circuitry of the INA138 can accurately measure beyond its power-supply voltage, V+. For example, the
V+ power supply can be 5 V, whereas the load power supply voltage is up to 36 V (or 60 V with the INA168).
The output voltage range of the OUT terminal, however, is limited by the lesser of the two voltages (see Output
Voltage Range). A 0.1-µF capacitor is recommenced to be placed near the power supply pin on the INA138 or
INA168. Additional capacitance may be required for applications with noisy power supply voltages.
10 Layout
10.1 Layout Guidelines
Figure 19 shows the basic connection of the INA138 device. The input pins, VIN+ and VIN– , should be connected
as closely as possible to the shunt resistor to minimize any resistance in series with the shunt resistance. The
output resistor, RL, is shown connected between pin 1 and ground. Best accuracy is achieved with the output
voltage measured directly across RL. This is especially important in high-current systems where load current
could flow in the ground connections, affecting the measurement accuracy.
No power-supply bypass capacitors are required for stability of the INA138. However, applications with noisy or
high-impedance power supplies may require decoupling capacitors to reject power-supply noise. Connect bypass
capacitors close to the device pins.
10.2 Layout Example
Figure 19. Typical Layout Example
l TEXAS INSTRUMENTS
19
INA138
,
INA168
www.ti.com
SBOS122E DECEMBER 1999REVISED DECEMBER 2017
Product Folder Links: INA138 INA168
Submit Documentation FeedbackCopyright © 1999–2017, Texas Instruments Incorporated
11 Device and Documentation Support
11.1 Documentation Support
11.1.1 Related Documentation
For related documentation see the following:
16 bit 1MSPS Data Acquisition Reference Design for Single-Ended Multiplexed Applications
ADS7870 12-Bit ADC, MUX, PGA and Internal Reference Data Acquisition System
TLV3201, TLV3202 40-ns, microPOWER, Push-Pull Output Comparators
REF200 Dual Current Source/Current Sink
11.2 Related Links
Table 1 lists quick access links. Categories include technical documents, support and community resources,
tools and software, and quick access to sample or buy.
Table 1. Related Links
PARTS PRODUCT FOLDER SAMPLE & BUY TECHNICAL
DOCUMENTS TOOLS &
SOFTWARE SUPPORT &
COMMUNITY
INA138 Click here Click here Click here Click here Click here
INA168 Click here Click here Click here Click here Click here
11.3 Receiving Notification of Documentation Updates
To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper
right corner, click on Alert me to register and receive a weekly digest of any product information that has
changed. For change details, review the revision history included in any revised document.
11.4 Community Resources
The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective
contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of
Use.
TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration
among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help
solve problems with fellow engineers.
Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and
contact information for technical support.
11.5 Trademarks
E2E is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
11.6 Electrostatic Discharge Caution
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
11.7 Glossary
SLYZ022 TI Glossary.
This glossary lists and explains terms, acronyms, and definitions.
l TEXAS INSTRUMENTS
20
INA138
,
INA168
SBOS122E DECEMBER 1999REVISED DECEMBER 2017
www.ti.com
Product Folder Links: INA138 INA168
Submit Documentation Feedback Copyright © 1999–2017, Texas Instruments Incorporated
12 Mechanical, Packaging, and Orderable Information
The following pages include mechanical, packaging, and orderable information. This information is the most
current data available for the designated devices. This data is subject to change without notice and revision of
this document. For browser-based versions of this data sheet, refer to the left-hand navigation.
TEXAS INSTRUMENTS Samples Samples Samples Sample: Sample: Samples Samples
PACKAGE OPTION ADDENDUM
www.ti.com 20-Aug-2021
Addendum-Page 1
PACKAGING INFORMATION
Orderable Device Status
(1)
Package Type Package
Drawing Pins Package
Qty Eco Plan
(2)
Lead finish/
Ball material
(6)
MSL Peak Temp
(3)
Op Temp (°C) Device Marking
(4/5)
Samples
INA138NA/250 ACTIVE SOT-23 DBV 5 250 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 125 B38
INA138NA/3K ACTIVE SOT-23 DBV 5 3000 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 125 B38
INA138NA/3KG4 ACTIVE SOT-23 DBV 5 3000 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 125 B38
INA168NA/250 ACTIVE SOT-23 DBV 5 250 RoHS & Green NIPDAU Level-2-260C-1 YEAR A68
INA168NA/250G4 ACTIVE SOT-23 DBV 5 250 RoHS & Green NIPDAU Level-2-260C-1 YEAR A68
INA168NA/3K ACTIVE SOT-23 DBV 5 3000 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 125 A68
INA168NA/3KG4 ACTIVE SOT-23 DBV 5 3000 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 125 A68
(1) The marketing status values are defined as follows:
ACTIVE: Product device recommended for new designs.
LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.
NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.
PREVIEW: Device has been announced but is not in production. Samples may or may not be available.
OBSOLETE: TI has discontinued the production of the device.
(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance
do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may
reference these types of products as "Pb-Free".
RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.
Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based
flame retardants must also meet the <=1000ppm threshold requirement.
(3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature.
(4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device.
(5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation
of the previous line and the two combined represent the entire Device Marking for that device.
I TEXAS INSTRUMENTS
PACKAGE OPTION ADDENDUM
www.ti.com 20-Aug-2021
Addendum-Page 2
(6) Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two
lines if the finish value exceeds the maximum column width.
Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information
provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and
continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.
TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.
In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.
OTHER QUALIFIED VERSIONS OF INA138, INA168 :
Automotive : INA138-Q1, INA168-Q1
NOTE: Qualified Version Definitions:
Automotive - Q100 devices qualified for high-reliability automotive applications targeting zero defects
I TEXAS INSTRUMENTS REEL DIMENSIONS TAPE DIMENSIONS 7 “KO '«m» Reel Diameter AD Dimension destgned to accommodate the component with ED Dimension destgned to accommodate the component \engm K0 Dimenslun destgneo to accommodate the component thickness , w OveraH wtdm loe earner tape i p1 Pitch between successwe cavuy cemers f T Reel Width (W1) QUADRANT ASSIGNMENTS FOR PIN 1 ORIENTATION IN TAPE O O O D O O D D SprocketHules ,,,,,,,,,,, ‘ User Direcllon 0' Feed Pockel Quadrams
TAPE AND REEL INFORMATION
*All dimensions are nominal
Device Package
Type Package
Drawing Pins SPQ Reel
Diameter
(mm)
Reel
Width
W1 (mm)
A0
(mm) B0
(mm) K0
(mm) P1
(mm) W
(mm) Pin1
Quadrant
INA138NA/250 SOT-23 DBV 5 250 178.0 9.0 3.3 3.2 1.4 4.0 8.0 Q3
INA138NA/3K SOT-23 DBV 5 3000 178.0 9.0 3.3 3.2 1.4 4.0 8.0 Q3
INA168NA/250 SOT-23 DBV 5 250 178.0 9.0 3.23 3.17 1.37 4.0 8.0 Q3
INA168NA/3K SOT-23 DBV 5 3000 178.0 9.0 3.23 3.17 1.37 4.0 8.0 Q3
PACKAGE MATERIALS INFORMATION
www.ti.com 15-May-2020
Pack Materials-Page 1
I TEXAS INSTRUMENTS TAPE AND REEL BOX DIMENSIONS
*All dimensions are nominal
Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)
INA138NA/250 SOT-23 DBV 5 250 180.0 180.0 18.0
INA138NA/3K SOT-23 DBV 5 3000 180.0 180.0 18.0
INA168NA/250 SOT-23 DBV 5 250 180.0 180.0 18.0
INA168NA/3K SOT-23 DBV 5 3000 180.0 180.0 18.0
PACKAGE MATERIALS INFORMATION
www.ti.com 15-May-2020
Pack Materials-Page 2
www.ti.com
PACKAGE OUTLINE
C
0.22
0.08 TYP
0.25
3.0
2.6
2X 0.95
1.9
1.45
0.90
0.15
0.00 TYP
5X 0.5
0.3
0.6
0.3 TYP
8
0 TYP
1.9
A
3.05
2.75
B
1.75
1.45
(1.1)
SOT-23 - 1.45 mm max heightDBV0005A
SMALL OUTLINE TRANSISTOR
4214839/F 06/2021
NOTES:
1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing
per ASME Y14.5M.
2. This drawing is subject to change without notice.
3. Refernce JEDEC MO-178.
4. Body dimensions do not include mold flash, protrusions, or gate burrs. Mold flash, protrusions, or gate burrs shall not
exceed 0.25 mm per side.
0.2 C A B
1
34
5
2
INDEX AREA
PIN 1
GAGE PLANE
SEATING PLANE
0.1 C
SCALE 4.000
www.ti.com
EXAMPLE BOARD LAYOUT
0.07 MAX
ARROUND 0.07 MIN
ARROUND
5X (1.1)
5X (0.6)
(2.6)
(1.9)
2X (0.95)
(R0.05) TYP
4214839/F 06/2021
SOT-23 - 1.45 mm max heightDBV0005A
SMALL OUTLINE TRANSISTOR
NOTES: (continued)
5. Publication IPC-7351 may have alternate designs.
6. Solder mask tolerances between and around signal pads can vary based on board fabrication site.
SYMM
LAND PATTERN EXAMPLE
EXPOSED METAL SHOWN
SCALE:15X
PKG
1
34
5
2
SOLDER MASK
OPENING
METAL UNDER
SOLDER MASK
SOLDER MASK
DEFINED
EXPOSED METAL
METAL
SOLDER MASK
OPENING
NON SOLDER MASK
DEFINED
(PREFERRED)
SOLDER MASK DETAILS
EXPOSED METAL
www.ti.com
EXAMPLE STENCIL DESIGN
(2.6)
(1.9)
2X(0.95)
5X (1.1)
5X (0.6)
(R0.05) TYP
SOT-23 - 1.45 mm max heightDBV0005A
SMALL OUTLINE TRANSISTOR
4214839/F 06/2021
NOTES: (continued)
7. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate
design recommendations.
8. Board assembly site may have different recommendations for stencil design.
SOLDER PASTE EXAMPLE
BASED ON 0.125 mm THICK STENCIL
SCALE:15X
SYMM
PKG
1
34
5
2
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