MAX6652 Datasheet by Analog Devices Inc./Maxim Integrated

Datasheet Feedback/Errors

[VI/JXI/VI [VI/JXI/VI WWI—WWW MAXIM LILILILILI

General Description

The MAX6652 system supervisor monitors multiple

power-supply voltages, including its own, and also fea-

tures an on-board temperature sensor. Voltages and

temperature are converted to an 8-bit code using an

analog-to-digital converter (ADC). A multiplexer automat-

ically sequences through the voltage and temperature

measurements. The digitized signals are then stored in

registers and compared to the over/under threshold lim-

its programmed over the 2-wire serial interface.

When a temperature measurement exceeds the pro-

grammed threshold, or when an input voltage falls out-

side the programmed voltage limits, the MAX6652

generates a latched interrupt output ALERT. Three inter-

rupt modes are available for temperature excursions:

default mode, one-time interrupt mode, and comparator

mode. The ALERT output is cleared, except for tempera-

ture interrupts generated in comparator mode, by read-

ing the interrupt status register (Table 5). The ALERT

output can also be masked by writing to the appropriate

bits in the interrupt mask register (Table 6) or by setting

bit 1 of the configuration register (Table 4) to 0. The

MAX6652 I2C™-compatible/SMBus interface also

responds to the SMB alert response address.

The 2-wire serial interface accepts both I2C and standard

system management bus (SMBus) write byte, read byte,

send byte, and receive byte commands to program the

alarm thresholds and to read voltage and temperature

data. Voltage data is scaled so that when the nominal

voltage is present at a pin (e.g., 3.3V for the 3.3VIN pin),

the conversion result is equal to 3/4 of the ADC full-scale

range or a decimal count of 192 (Table 3). The tempera-

ture data format is 7 bits plus sign, with each data bit

representing 1°C, in two's complement format (Table 2).

The MAX6652 has only one address pin, ADD. One of

four different address codes can be selected by con-

necting the ADD pin to GND, VCC, SDA, or SCL.

Whenever an I2C-compatible/SMBus transaction is initiat-

ed, the two LSBs of the slave address register are deter-

mined by connection, setting the chip address to one of

four possible values. In addition, an address code can

also be directly written to the serial address register. This

code will overwrite the code set by connection of the

ADD pin, until the MAX6652 is taken through a power-on

reset cycle.

The MAX6652 features 60Hz or 50Hz line-frequency

rejection for optimal performance. The device operates

from +2.7V to +5.5V and is specified for operation from

-40°C to +125°C. It is available in a tiny 10-pin µMAX

package.

Features

♦Monitors Four Voltages (2.5V, 3.3V, 12V, VCC)

♦Monitors Local Temperature

♦Temperature Measurement Accuracy,

±2°C (TA= +25°C)

♦User-Programmable Voltage and Temperature

Thresholds

♦Alert Function with Ability to Respond to SMB

Alert Response Address

♦+2.7V to +5.5V Supply Range

♦-40°C to +125°C Temperature Range

♦60Hz or 50Hz Line-Frequency Rejection

♦Tiny 10-Pin µMAX Package

Applications

MAX6652

Temperature Sensor and System Monitor

in a 10-Pin µMAX

________________________________________________________________ Maxim Integrated Products 1

VCC

SCL

SDA

ADDN.C.

3.3VIN

2.5VIN

12VIN

MAX6652

µMAX

TOP VIEW

GND ALERT

Pin Configuration

19-1959; Rev 1; 8/01

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at

1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

Ordering Information

PART TEMP. RANGE PIN-PACKAGE

MAX6652AUB -40°C to +125°C 10 µMAX

I2C is a trademark of Philips Corp.

Workstations

Servers

Networking

Telecommunications

Typical Application Circuit and Functional Diagram appear

at end of data sheet.

[MAXI/VI

MAX6652

Temperature Sensor and System Monitor

in a 10-Pin µMAX

2 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS

(TA= -40°C to +125°C, unless otherwise noted. Typical values are at VCC = +5V, TA= +25°C.)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional

operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to

absolute maximum rating conditions for extended periods may affect device reliability.

VCC ........................................................................-0.3V to +6.0V

Voltage on 12VIN ...................................................-0.3V to +16V

All Other Pins ........................................................-0.3V to +6.0V

Output Current (SDA, ALERT) ............................-1mA to +50mA

Junction Temperature .....................................................+150°C

Operating Temperature Range ........................-40°C to +125°C

Storage Temperature Range ............................-65°C to +150°C

Continuous Power Dissipation (TA= +70°C)

10-Pin µMAX (derate 5.6mW/°C above +70°C) ..........444mW

Lead Temperature (soldering, 10s) ................................+300°C

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

POWER SUPPLY

Supply Voltage VCC 2.7 5.5 V

ICC Active 200 500 µA

Supply Current ISD Shutdown mode, all digital inputs are

grounded <1 10 µA

Power-On Reset Voltage VCC_ rising or falling edge 2 V

TEMPERATURE

TA = +25°C±2

-20°C ≤ TA ≤ +80°C±3°CAccuracy (Note 5) VCC = +5V

-40°C ≤ TA ≤ +125°C±5

PSRR VCC = +2.7V to +5.5V 0.7 1.3 °C/V

Resolution ±1 °C

ADC CHARACTERISTICS

Total Unadjusted Error TUE VIN > 10LSB ±1 ±1.5 %

Differential Nonlinearity DNL VIN > 10LSB ±1 LSB

Supply Sensitivity PSS VCC = +2.7V to +5.5V ±1 V

Input Resistance RIN 12VIN, 2.5VIN, 3.3VIN 100 150 200 kΩ

Total Monitoring Cycle Time tc (Note 1) 200 300 ms

SCL, SDA, ADD

Logic Input Low Voltage VIL 0.8 V

VCC ≤ 3.6V 2.0 V

Logic Input High Voltage VIH VCC > 3.6V 2.6 V

SDA Output Low Voltage VOL ISINK = 3mA 400 mV

Input Leakage Current ILEAK VIN = 0 or 5V ±1 µA

ALERT

ISINK = 1.2mA, VCC > 2.7V 0.3 V

Output Low Voltage VOLA ISINK = 3.2mA, VCC > 4.5V 0.4 V

TIMING

Serial Clock Frequency fSCL 0 400 kHz

Bus Free Time Between STOP and

START tBUF 1.3 µs

ABSOLUTE MAXIMUM RATINGS

All Voltages Are Referenced to GND

n [MAXI/VI

MAX6652

Temperature Sensor and System Monitor

in a 10-Pin µMAX

_______________________________________________________________________________________ 3

Note 1: Total monitoring time includes temperature conversion and four analog input voltage conversions.

Note 2: A master device must provide at least a 300ns hold time for the SDA signal, referred to VIL of the SCL signal, to bridge the

undefined region of SCL’s falling edge.

Note 3: CB= total capacitance of one bus line in pF. Rise and fall times are measured between 0.3 x VCC to 0.7 x VCC.

Note 4: Input filters on SDA, SCL, and ADD suppress noise spikes <50ns.

Note 5: Guaranteed but not tested over the entire temperature range.

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

START Condition Hold Time tHD:STA 0.6 µs

STOP Condition Hold Time tSU:STO 0.6 µs

Clock Low Period tLOW 1.3 µs

Clock High Period tHIGH 0.6 µs

Data Setup Time tSP:DAT 100 ns

Data Hold Time tHD:DAT (Note 2) 0 0.9 µs

Receive SCL/SDA Minimum

Rise Time tR(Note 3) 20 +

0.1CBns

Receive SCL/SDA Maximum

Rise Time tR(Note 3) 300 ns

Receive SCL/SDA Minimum

Fall Time tF(Note 3) 20 +

0.1CBns

Receive SCL/SDA Maximum

Fall Time tF(Note 3) 300 ns

Transmit SDA Fall Time tF400pF, ISINK = 3mA 20 +

0.1CB300 ns

Pulse Width of Spike

Suppressed tSP (Note 4) 50 ns

ELECTRICAL CHARACTERISTICS (continued)

(TA= -40°C to +125°C, unless otherwise noted. Typical values are at VCC = +5V, TA= +25°C.)

Typical Operating Characteristics

(VCC = +5V, ADD = GND, ALERT = 10kΩto VCC, TA= +25°C, unless otherwise noted.)

100

200

150

250

300

2.5 3.5 4.03.0 4.5 5.0 5.5

SUPPLY CURRENT

vs. SUPPLY VOLTAGE

MAX6652 toc01

SUPPLY VOLTAGE (V)

SUPPLY CURRENT (µA)

A: T

= +125°C

B: T

= +85°C

C: T

= +25°C

D: T

= 0°C

E: T

= -40°C

250

225

200

175

150

1 1000

SUPPLY CURRENT

vs. SCL CLOCK FREQUENCY

MAX6652 toc02

CLOCK FREQUENCY (kHz)

SUPPLY CURRENT (µA)

VCC = +5V

SCL = 0 to +5V

-5

-2

-3

-4

-1

2.5 3.53.0 4.0 4.5 5.0 5.5

TEMPERATURE ERROR

vs. SUPPLY VOLTAGE

MAX6652 toc03

SUPPLY VOLTAGE (V)

TEMPERATURE ERROR (°C)

= +85°C

= 0°C

= -40°C

lVI/lxlllfl

MAX6652

Temperature Sensor and System Monitor

in a 10-Pin µMAX

4 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VCC = +5V, ADD = GND, ALERT = 10kΩto VCC, TA= +25°C, unless otherwise noted.)

1k 10k

-10

-8

-6

-2

-4

1 10 100

TEMPERATURE ERROR

vs. SUPPLY NOISE FREQUENCY

MAX6652 toc04

SUPPLY NOISE FREQUENCY (kHz)

TEMPERATURE ERROR (°C)

-9

-7

-3

-5

-1

200mVp-p

= +5V

BYPASS CAP REMOVED

TEMPERATURE ERROR

vs. TEMPERATURE

MAX6652 toc05

-1.00

-0.75

-0.25

-0.50

0.50

0.75

0.25

1.00

TEMPERATURE ERROR (°C)

-50 0 25-25 50 75 100 125

TEMPERATURE (°C)

PIN NAME FUNCTION

1 12VIN Analog Input. Monitors 12V supply.

2 2.5VIN Analog Input. Monitors 2.5V supply.

3 3.3VIN Analog Input. Monitors 3.3V supply.

4 N.C. No Connection. Can be connected to GND to improve thermal conductivity.

5 GND Ground

6ALERT SMBus Alert (Interrupt) Output, Open Drain. Alerts the master that a temperature or voltage limit

has been violated.

7 ADD

SMBus Address Select Input. ADD is sampled at the beginning of each I2C-compatible/SMBus

transaction, and the 2 LSBs of the slave address register are detemined by ADD's connection to

GND, SDA, SCL, or VCC.

8 SDA I2C-Compatible/SMBus Serial Data Interface

9 SCL I2C-Compatible/SMBus Serial Clock Input

10 VCC Supply Voltage Input, +2.7V to +5.5V. Also serves as a voltage monitor input. Bypass VCC to GND

with a 0.1µF capacitor.

Pin Description

01010000 X (+80” x (+65” ult on [MAXI/VI

Detailed Description

The MAX6652 is a voltage and temperature monitor

designed to communicate through an I2C-compatible/

SMBus interface with an external microcontroller (µC).

A µC with no built-in I2C-compatible or SMBus capabili-

ties can generate SMBus serial commands by “bit-

banging” general-purpose input-output (GPIO) pins.

The MAX6652 can monitor external supply voltages of typi-

cally 2.5V, 3.3V, and 12V, as well as its own supply voltage

and temperature. This makes it ideal for supervisor and

thermal management applications in telecommunications,

desktop and notebook computers, workstations, and net-

working equipment. All inputs are converted to an 8-bit

code using an ADC with an oversampling ratio of 8 to

improve noise rejection. The oversampling ratio can be

reduced by a factor of 4, with a corresponding reduc-

tion in the monitoring cycle time, by setting bit 5 of the

configuration register to 1. Each input voltage is scaled

down by an on-chip resistive divider so that its output,

at the nominal input voltage, is 3/4 of the ADC’s full-

scale range, or a decimal count of 192 (Table 3). Table

1 is the register map and Table 2 is the temperature

data format.

MAX6652

Temperature Sensor and System Monitor

in a 10-Pin µMAX

_______________________________________________________________________________________ 5

ADDRESS READ/WRITE POWER-ON DEFAULT DESCRIPTION

20h R —Data register for 2.5 VIN measurement

21h R —Data register for 12VIN measurement

22h R —Data register for 3.3VIN measurement

23h R —Data register for VCC measurement

27h R —Data register for temperature measurement

2Bh R/W 1101 0011 (1.1 ✕ 2.5V) High limit for 2.5VIN

2Ch R/W 1010 1101 (0.9 ✕ 2.5V) Low limit for 2.5VIN

2Dh R/W 1101 0011 (1.1 ✕ 12V) High limit for 12VIN

2Eh R/W 1010 1101 (0.9 ✕ 12V) Low limit for 12VIN

2Fh R/W 1101 0011 (1.1 ✕ 3.3V) High limit for 3.3VIN

30h R/W 1010 1101 (0.9 ✕ 3.3V) Low limit for 3.3VIN

31h R/W 1101 0011 (1.1 ✕ 5V) High limit for VCC

32h R/W 1010 1101 ✕ (0.9 ✕ 5V) Low limit for VCC

39h R/W 0101 0000 ✕ (+80°C) Hot temperature limit

3Ah R/W 0100 0001 ✕ (+65°C) Hot temperature hysteresis

40h R/W 0000 1000 Configuration register

41h R 0000 0000 Interrupt status register

43h R/W 0000 0000 Interrupt mask register

48h R/W 0010 1XXY

Device address register. The values of XX are

dependent on the status of the ADD pin.

Power-On Default ADD Connection

0010 100Y To GND

0010 101Y To VCC

0010 110Y To SDA

0010 111Y To SCL

Y (bit 0) is the SMBus read/write bit. When the 7-

bit chip address is read back from the serial

address register, an 8-bit word will be presented

with a 0 in bit 0 (Y).

4Bh R/W 0000 0000 Temperature configuration register

Table 1. Register Map

lVI/lxlllfl

MAX6652

Writing a 1 to bit 0 of the configuration register starts

the monitoring function. The device will perform a

sequential sampling of all the inputs, starting with the

internal temperature sensor and continuing with 2.5VIN,

12VIN, 3.3VIN, and VCC. If the master terminates the

conversion, the sequential sampling will not stop until

the sampling cycle is completed and the results are

stored. When it starts again, it will always start with the

temperature measurement.

An interrupt signal is generated when a temperature

measurement goes above the hot limit or when a volt-

age measurement is either above the high limit or

below the low limit. This will cause the open-drain out-

put (ALERT) to go to the active-low state and set each

corresponding interrupt status bit (bits 0 through 4) to 1

(Table 5). The interrupt will be cleared by reading the

interrupt status register, except for temperature inter-

rupts generated in comparator mode. Reading the

interrupt status register also clears the register itself,

except for temperature interrupt bits set in comparator

mode.

Unless the fault is removed, the ALERT output will only

remain cleared until the end of the next conversion

cycle where it will again be asserted. The ALERT output

can also be masked by writing to the appropriate bits in

the interrupt mask register (Table 6) or by setting bit 1

of the configuration register (Table 4) to 0.

ADC and Multiplexer

The ADC integrates over a 66ms period, an integral

multiple of the line period with excellent noise rejection.

The internal oscillator is trimmed to produce a 66ms

conversion time for temperature and 33ms for each

voltage. This is equivalent to 4 and 2 cycles of 60Hz,

respectively, and provides protection against noise

pickup from the main supply. The internal oscillation

frequency can be changed to provide the same protec-

tion against 50Hz by setting bit 7 in the configuration

sequences through the inputs, measuring voltages, and

temperature.

Temperature Sensor and System Monitor

in a 10-Pin µMAX

6 _______________________________________________________________________________________

TEMPERATURE

(°C)

DIGITAL

OUTPUT

(BINARY)

DIGITAL

OUTPUT

(HEX)

+125 0111 1101 7D

+25 0001 1001 19

+1 0000 0001 01

0 0000 0000 00

-1 1111 1111 FF

-25 1110 0111 E7

-40 1101 1000 D8

Table 2. Temperature Data Format

ADC OUTPUT

CODE

INPUT VOLTAGE AT

12VIN

INPUT VOLTAGE AT

2.5VIN

INPUT VOLTAGE AT

3.3VIN VCC

LSB weight 62mV (12V/192) 13mV (2.5V/192) 17.2mV (3.3V/192) 26mV (5.0V/192)

0 < 62mV < 13mV < 17.2mV —

1 62mV - 125mV 13mV - 26mV 17.2mV - 34.4mV —

2 125mV - 187mV 26mV - 39mV 34.4mV - 51.6mV —

———— —

64 (1/4 scale) 4.000V - 4.063V 833mV - 846mV 1.100V - 1.117V —

———— —

128 (1/2 scale) 8.000V - 8.063V 1.667V - 1.680V 2.200V - 2.217V 3.330V - 3.560V

———— —

192 (3/4 scale) 12.000V - 12.063V 2.500V - 2.513V 3.300V - 3.317V 5.000V - 5.026V

———— —

253 15.813V - 15.875V 3.294V - 3.307V 4.348V - 4.366V 6.566V - 6.615V

254 15.875V - 15.938V 3.572V - 3.586V 4.366V - 4.383V 6.615V - 6.640V

255 > 15.938 > 3.586 > 4.383 > 6.640

Table 3. Voltage Data Format

[MAXI/VI

MAX6652

Temperature Sensor and System Monitor

in a 10-Pin µMAX

_______________________________________________________________________________________ 7

Table 5. Interrupt Status Register (Address 41h, Power-Up Default = 00h)

Table 4. Configuration Register (Address 41h, Power-Up Default = 00h)

BIT NAME READ/WRITE DESCRIPTION

0 Start/Stop R/W

This bit controls the monitoring loop. Setting the bit to 0 stops the

monitoring loop and puts the device into shutdown mode. The I2C/SMBus

interface is still active during the shutdown mode. Setting the bit to 1 starts

the monitoring cycle. All high/low limits should be set before setting this

bit to 1.

1 Interrupt Enable R/W

This bit is used to enable or disable the interrupt output. Setting the bit to

1 enabes the interrupt output; setting the bit to 0 disables the interrupt

output.

2 Reserved ——

3 Interrupt Clear R/W

This bit is used to clear the interrupt output when it is set to high. It will not

affect the interrupt status register. The monitoring loop will not start until

the bit is set to 0.

4Line Frequency

Select R/W

This bit controls the internal clock frequency. Setting the bit to 1 changes

the clock frequency to 51.2kHz from 61.4kHz. This can improve the

measurement accuracy when the power-line frequency is at 50Hz.

5 Short Cycle R/W This bit reduces the conversion rate by a factor of four when it is set to 1.

6 Reserved ——

7 Reset R/W

This bit is used as a reset signal for the register initialization. The 1 of this

bit will reset all the register values into the power-up default mode,

including bit 7 itself.

BIT NAME READ/WRITE DESCRIPTION

0 2.5VIN Error R A 1 indicates either a high or low limit has been exceeded at the 2.5VIN

input.

1 12VIN Error R A 1 indicates either a high or low limit has been exceeded at the 12VIN

input.

2 3.3VIN Error R A 1 indicates either a high or low limit has been exceeded at the 3.3VIN

input.

CC Error R A 1 indicates either a high or low limit has been exceeded at the VCC input.

4 Temperature Error R

A 1 indicates either a high or low limit has been exceeded at the internal

temperature sensor. The conditions that will generate and clear this bit

depend on the temperature interrupt mode selected by bits 0 and 1 in the

temperature configuration register.

5, 6, 7 Reserved ——

lVI/lxlllfl

MAX6652

Low-Power Shutdown Mode

Setting bit 0 in the configuration register to 0 stops the

monitoring loop and puts the MAX6652 into low-power

shutdown mode. In this mode, the I2C-compatible/

SMBus interface remains active, and the supply current

drops to 10µA or less.

Power-On Reset (POR)

The MAX6652 power-on reset supply (POR) voltage is

typically 2V. Below this supply voltage, all registers are

reset, the device is put into shutdown mode, and the

I2C-compatible/SMBus interface is inactive.

Alarm Threshold Registers

Two registers, a hot temperature limit (THOT) at 39h and

a hot temperature hysteresis (THYST) at 3Ah, store

alarm threshold data (Table 1). If a measured tempera-

ture exceeds the value of THOT, an ALERT is asserted.

Alerts are cleared and reasserted depending on the

interrupt mode selected in the temperature configura-

tion register (see

ALERT

Interrupts).

The POR state of the THOT register is 0101 0000 or

+80°C. The POR state of the THYST register is 0100

0001 or +65°C.

High and low limits for the voltage inputs are stored in

registers 2Bh through 32h. If a measured voltage is

less than VLOW or greater than VHIGH, an ALERT is

asserted.

The POR states of the high- and low-voltage limits are

1.1 and 0.9 times the nominal voltage for each input,

respectively.

Interrupt Status Byte Functions

The interrupt status register records temperature or

voltage fault conditions whenever a limit is exceeded

(Table 5). Bits 0 through 3 correspond to the 2.5V, 12V,

3.3V, and 5V internal VCC voltage inputs, and bit 4 cor-

responds to the temperature. If a threshold has been

crossed, the appropriate bit will contain a 1. In the

default and one-time interrupt modes, reading the sta-

tus register clears the register until a new out-of-range

condition is detected.

ALERT

Interrupts

An out-of-range voltage or temperature causes the

ALERT output signal to be asserted. However, if the

assertion is caused by an out-of-range temperature, the

ALERT output can operate in one of three different

modes: default, one-time interrupt, and comparator

modes. The ALERT signal can be cleared only by read-

ing the interrupt status register (Table 5), except when

the ALERT has been activated by an out-of-range tem-

perature in comparator mode. In this case, ALERT is

only cleared when the fault is removed. Reading the

interrupt status register also clears this register, except

for bit 4 in comparator mode. Unless the fault is

removed, ALERT will be reasserted after the next con-

version cycle. The ALERT output can also be masked

by writing to the appropriate bits in the interrupt mask

The interrupt does not halt conversions. New tempera-

ture and voltage data continue to be available over the

I2C-compatible/SMBus interface after ALERT is assert-

ed. The three temperature ALERT modes are illustrated

in Figure 1 and are selected through the temperature

configuration register (Table 7). The ALERT output pin

is open drain, so the device can share a common inter-

rupt line.

Temperature Sensor and System Monitor

in a 10-Pin µMAX

8 _______________________________________________________________________________________

Table 6. Interrupt Mask Register (Address 43h, Power-Up Default = 00h)

BIT NAME READ/WRITE DESCRIPTION

0 2.5V R/W Setting the bit to 1 disables the interrupt status register bit (bit 0) and the ALERT

output for the 2.5VIN input.

1 12V R/W Setting the bit to 1 disables the interrupt status register bit (bit 1) and the ALERT

output for the 12VIN input.

2 3.3V R/W Setting the bit to 1 disables the interrupt status register bit (bit 2) and the ALERT

output for the 3.3VIN input.

3 5.0V R/W Setting the bit to 1 disables the interrupt status register bit (bit 3) and the ALERT

output for the VCC input.

4 Tem p er atur e R/W Setting the bit to 1 disables the interrupt status register bit (bit 4) and the ALERT

output for temperature.

5, 6, 7 Reserved ——

[MAXI/VI

MAX6652

_______________________________________________________________________________________ 9

Temperature Sensor and System Monitor

in a 10-Pin µMAX

Default Mode

An interrupt is initiated when temperature exceeds

THOT (address 39Ah). The interrupt is cleared only by

reading the interrupt status register. An interrupt will

continue to be generated on subsequent measure-

ments until temperature goes below THYST (address

3Ah).

One-Time Interrupt Mode

An interrupt is initiated when temperature exceeds

THOT (address 39Ah). The interrupt is cleared only by

reading the interrupt status register. The next interrupt

is then initiated when temperature falls below the THYST

(address 3Ah).

Comparator Mode

An interrupt is initiated when temperature exceeds

THOT (address 39Ah). The ALERT output will remain

asserted low until the temperature goes below THOT.

Reading the interrupt status register will not clear the

ALERT output or interrupt status bit in the register. The

interrupt will continue to be generated on subsequent

measurements until temperature falls below THOT.

Figure 1 shows successive interrupts and clears using

a temperature fault as an example.

I2C-Compatible/SMBus Digital Interface

From a software perspective, the MAX6652 appears as

a set of byte-wide registers that contain voltage and

temperature data, alarm threshold values, or control

bits.

The device employs four standard I2C-compatible/

SMBus protocols: write byte, read byte, send byte, and

receive byte (Figures 2, 3, 4).

Slave Address

The device address can be set to one of four different

values by pin strapping ADD to GND, SDA, SCL, or

VCC, so more than one MAX6652 can reside on the

same bus without address conflicts (Table 1). The

address pin state is checked at the beginning of each

I2C-compatible/SMBus transaction and so is insensitive

to glitches on VCC. Any address code can also be writ-

ten to the serial address register and will overwrite the

code set by connecting the ADD pin until the MAX6652

is taken through a POR cycle.

The MAX6652 also responds to the SMBus alert

response address (see Alert Response Address).

Alert Response Address

The SMBus alert response interrupt pointer provides

quick fault identification for simple slave devices that

lack the complex, expensive logic needed to be a bus

master. Usually the ALERT outputs of several slave

devices are wired-ORed to the same interrupt input of

the host master. Upon receiving an interrupt signal, the

host master can broadcast a receive byte transmission

(Figure 2) with the alert response address (0001 1000).

Then, any slave device that generated an interrupt

attempts to identify itself by putting its own address on

the bus.

The alert response can activate several different slave

devices simultaneously, similar to the I2C general call. If

more than one slave attempts to respond, bus arbitra-

tion rules apply, and the device with the lower address

code wins. The losing device does not generate an

acknowledge signal and continues to hold the interrupt

line low until serviced. The MAX6652 does not automat-

ically clear its ALERT when it responds to an alert

response address. The host master must then clear or

mask the ALERT by reading the interrupt status regis-

ter, writing to the interrupt mask register, or setting bit 1

of the configuration register to 0 before it can identify

other slaves generating an interrupt.

Command Byte Functions

The 8-bit command byte register (Table 1) is the master

index that points to the other data, configuration, limits,

and address registers within the MAX6652. The func-

tions of those other registers are described below.

Configuration Byte Functions

The configuration register (Table 4) is a read-write reg-

ister with several functions:

Bit 0 puts the MAX6652 into software standby mode

(STOP) or autoconvert (START) mode. The 2-wire inter-

face is still active in the standby mode. All voltage and

temperature limits should be set before setting this bit

to 1.

Bit 1 enables and disables the ALERT output. Setting

this bit to 1 enables the ALERT output.

Bit 2 is reserved.

Bit 3 clears the ALERT output and stops the monitoring

loop when set to 1. Clearing the output will not affect

the contents of the interrupt status registers.

Bit 4 sets the analog-to-digital conversion speed to

minimize interference from power-line frequencies.

Setting this bit to 1 can improve accuracy when the

power-line frequency is 50Hz. When the power-line fre-

quency is 60Hz, bit 4 should be 0.

Bit 5 reduces the oversampling ratio in the ADC from 8

to 2. This reduces the monitoring cycle time by a factor

of 4 to typically 50ms at the cost of reduced noise

rejection.

lVI/lxlllfl

MAX6652

Temperature Sensor and System Monitor

in a 10-Pin µMAX

10 ______________________________________________________________________________________

Bit 6 is reserved.Bit 7 resets all register values to their

power-up default values. To reset all registers, set bit 7

to 1. This will also reset bit 7 to its power-up value of 0.

Applications Information

Sensing Circuit Board and Component

Temperatures

Temperature sensor ICs like the MAX6652 that sense

their own die temperatures must be mounted on or

close to the object whose temperature they are intend-

ed to measure. Because there is a good thermal path

between the 10-pin µMAX package’s metal leads and

the IC die, the MAX6652 can accurately measure the

temperature of the circuit board to which it is soldered.

If the sensor is intended to measure the temperature of

a heat-generating component on the circuit board, it

should be mounted as close as possible to that compo-

nent and should share supply and ground traces (if

they are not noisy) with that component where possible.

This will maximize the heat transfer from the component

to the sensor.

The thermal path between the plastic package and the

die is not as good as the path through the leads, so the

MAX6652, like all temperature sensors in plastic pack-

ages, will be less sensitive to the temperature of the

surrounding air than to the temperature of the leads.

As with any IC, the wiring and circuits must be kept

insulated and dry to avoid leakage and corrosion,

especially if the part will be operated at cold tempera-

tures where condensation can occur.

Chip Information

TRANSISTOR COUNT: 13,446

PROCESS: BiCMOS

INTERRUPT

STATUS READ

THOT

THYST

TEMPERATURE

MONITORING CYCLE

DEFAULT MODE

ONE-TIME

INTERRUPT MODE

COMPARATOR MODE

ALERT

Figure 1. Alert Response to Temperature Interrupts

Table 7. Temperature Configuration Register

BIT NAME R/W DESCRIPTION

0-1 Hot Temperature Interrupt

Mode Select R/W

Bit 1, Bit 0  00: Default Mode

Bit 1, Bit 0  01: One-Time Interrupt Mode

Bit 1, Bit 0  10: Comparator Mode

Bit 1, Bit 0  11: Default Mode

2-7 Reserved R/W —

[MAXI/VI

MAX6652

Temperature Sensor and System Monitor

in a 10-Pin µMAX

______________________________________________________________________________________ 11

SMBCLK

AB CD

EFG H

IJK

SMBDATA

tSU:STA tHD:STA

tLOW tHIGH

tSU:DAT tHD:DAT tSU:STO tBUF

A = START CONDITION

B = MSB OF ADDRESS CLOCKED INTO SLAVE

C = LSB OF ADDRESS CLOCKED INTO SLAVE

D = R/W BIT CLOCKED INTO SLAVE

E = SLAVE PULLS SMBDATA LINE LOW

F = ACKNOWLEDGE BIT CLOCKED INTO MASTER

G = MSB OF DATA CLOCKED INTO SLAVE

H = LSB OF DATA CLOCKED INTO SLAVE

I = MASTER PULLS DATA LINE LOW

J = ACKNOWLEDGE CLOCKED INTO SLAVE

K = ACKNOWLEDGE CLOCK PULSE

L = STOP CONDITION

M = NEW START CONDITION

Figure 3. I2C/SMBus Write Timing Diagram

Write Byte Format

Read Byte Format

Send Byte Format Receive Byte Format

Slave Address: equiva-

lent to chip-select line of

a 3-wire interface

Command Byte: selects which

Data Byte: data goes into the register

set by the command byte (to set

thresholds, configuration masks, and

sampling rate)

Slave Address: equiva-

lent to chip-select line

Command Byte: selects

which register you are

reading from

Slave Address: repeated

due to change in data-

flow direction

Data Byte: reads from

the register set by the

command byte

Data Byte: writes data to the

last read byte or write byte

transmission

Data Byte: reads data from

the register commanded

by the last read byte or

write byte transmission;

also used for SMBus alert

response return address

S = Start condition

P = Stop condition

Shaded = Slave transmission

A = Not acknowledged

ACK

7 bits

ADDRESS ACK

8 bits

DATA ACK P

8 bits

S COMMANDWR

ACK

7 bits

ADDRESS ACK S ACK

8 bits

DATA

7 bits

ADDRESS RD

8 bits

PS COMMAND A

ACK

7 bits

ADDRESS

8 bits

COMMAND ACK PS WR ACK

7 bits

ADDRESS RD

8 bits

DATA PS A

Figure 2. I2C/SMBus Protocols

IVl/le/VI \H— MAXIIIII

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are

implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600

MAX6652

Temperature Sensor and System Monitor

in a 10-Pin µMAX

Typical Application Circuit

0.1µF

VCC

10kΩ

SCL

SDA

ADD

GND

3.3VIN

12VIN

2.5VIN

TO 3.3V

3.3V

TO 12V

TO 2.5V

N.C.

ALERT

CPU

MAX6652

I2C/SMBus

CONTROLLER

VCC

SCL

SDA

ADD

3.3VIN

12VIN

2.5VIN

ALERT

ADC

VOLTAGE

REFERENCE

DATA AND

CONTROL

LOGIC

TEMPERATURE

SENSOR

INPUT VOLTAGE

SCALING AND

MULTIPLEXER

I2C/SMBus-

COMPATIBLE

INTERFACE

MAX6652

Functional Diagram

Figure 4. I2C/SMBus Read Timing Diagram

SMBCLK

AB CD

EFG H

IJK

SMBDATA

tSU:STA tHD:STA

tLOW tHIGH

tSU:DAT tHD:DAT tSU:STO tBUF

F = ACKNOWLEDGE BIT CLOCKED INTO MASTER

G = MSB OF DATA CLOCKED INTO MASTER

H = LSB OF DATA CLOCKED INTO MASTER

I = MASTER PULLS DATA LINE LOW

J = ACKNOWLEDGE CLOCKED INTO SLAVE

K = ACKNOWLEDGE CLOCK PULSE

L = STOP CONDITION

M = NEW START CONDITION

A = START CONDITION

B = MSB OF ADDRESS CLOCKED INTO SLAVE

C = LSB OF ADDRESS CLOCKED INTO SLAVE

D = R/W BIT CLOCKED INTO SLAVE

E = SLAVE PULLS SMBDATA LINE LOW

MAX6652 Datasheet by Analog Devices Inc./Maxim Integrated

INFORMATION

HELP

CONTACT US

FOLLOW US