MAX7501MSA+T - Maxim - Datasheet.Directory

General Description

The MAX7500–MAX7504 temperature sensors accu-

rately measure temperature and provide an overtem-

perature alarm/interrupt/shutdown output. These

devices convert the temperature measurements to digi-

tal form using a high-resolution, sigma-delta, analog-to-

digital converter (ADC). Communication is through an

I2C-compatible 2-wire serial interface. The MAX7500/

MAX7501/MAX7502 integrate a timeout feature that

offers protection against I2C bus lockups. The

MAX7503/MAX7504 do not include the timeout feature.

The 2-wire serial interface accepts standard write byte,

read byte, send byte, and receive byte commands to

read the temperature data and configure the behavior

of the open-drain overtemperature shutdown output.

The MAX7500 features three address select lines, while

the MAX7501–MAX7504 feature two address select

lines and a RESET input. The MAX7500/MAX7501/

MAX7502s’ 3.0V to 5.5V supply voltage range, low

250µA supply current, and a lockup-protected I2C-com-

patible interface make them ideal for a wide range of

applications, including personal computers (PCs), elec-

tronic test equipment, and office electronics.

The MAX7500–MAX7504 are available in 8-pin µMAX®

and SO packages and operate over the -55°C to

+125°C temperature range.

Applications

PCs

Servers

Office Electronics

Electronic Test Equipment

Industrial Process Control

Features

♦Timeout Prevents Bus Lockup (MAX7500,

MAX7501, MAX7502)

♦Hardware Reset for Added Protection

♦I2C Bus Interface

♦3.0V to 5.5V Supply Voltage Range

♦250µA (typ) Operating Supply Current

♦3µA (typ) Shutdown Supply Current

♦±1.5°C (max) Temperature Accuracy (-25°C to

+100°C, 3-σ)

♦µMAX, SO Packages Save Space

♦Separate Open-Drain OS Output Operates as

Interrupt or Comparator/Thermostat Input

♦Register Readback Capability

♦Improved LM75 Second Source

MAX7500–MAX7504

Digital Temperature Sensors and Thermal

Watchdog with Bus Lockup Protection

________________________________________________________________

Maxim Integrated Products

Ordering Information/

Selector Guide

19-3382; Rev 4; 10/10

EVALUATION KIT

AVAILABLE

PART TEMP

RANGE

PIN-

PACKAGE RESET TIMEOUT

MAX7500MSA -55°C to

+125°C 8 SO X X

Ordering Information/Selector Guide continued at end of

data sheet.

Pin Configurations appear at end of data sheet.

µMAX is a registered trademark of Maxim Integrated Products, Inc.

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim's website at www.maxim-ic.com.

MAX7501

MAX7502

MAX7503

MAX7504

+3.0V TO +5.5V+3.0V TO +5.5V

+VS

RESET

GND

SCL

SDA

TO I2C MASTER

4.7kΩ

+VS

GND

SCL

SDA

TO I2C MASTER

4.7kΩ

MAX7500

Typical Application Circuits

MAX7500–MAX7504

Digital Temperature Sensors and Thermal

Watchdog with Bus Lockup Protection

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(+VS = +3.0V to +5.5V, TA= -55°C to +125°C, unless otherwise noted. Typical values are at +VS= +3.3V, TA= +25°C.) (Notes 4, 5)

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.

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifica-

tions do not apply when operating the device beyond its rated operating conditions.

Note 2: When the input voltage (VI) at any pin exceeds the power supplies (VI< VGND or VI> + VS), the current at that pin should be

limited to 5mA. The 20mA maximum package input current rating limits the number of pins that can safely exceed the power

supplies with an input current of 5mA to 4.

Note 3: Human Body Model, 100pF discharged through a 1.5kΩresistor.

(Note 1)

+VSto GND ............................................................. -0.3V to +6V

OS, SDA, SCL to GND.......................................... -0.3V to +6.0V

All Other Pins to GND................................ -0.3V to (+VS+ 0.3V)

Input Current at Any Pin (Note 2) ..................................... +5mA

Package Input Current (Note 2) ..................................... +20mA

ESD Protection (all pins, Human Body Model, Note 3)... ±2000V

Continuous Power Dissipation (TA = +70°C)

8-Pin µMAX (derate 4.5mW/°C above +70°C) ............ 362mW

8-Pin SO (derate 5.9mW/°C above +70°C)................. 471mW

Operating Temperature Range ....................... -55°C to +125°C

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

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

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

Soldering Temperature (reflow)

Lead(Pb)-free.............................................................. +260°C

Containing lead(Pb) .................................................... +240°C

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

-25°C ≤ TA ≤ +100°C -2.0 ±2.0

Accuracy, 6-σ

-55°C ≤ TA ≤ +125°C -3.0 ±3.0

°C

-25°C ≤ TA ≤ +100°C -1.5 +1.5

Accuracy, 3-σ (Note 5) -55°C ≤ TA ≤ +125°C -2.0 +2.0

°C

Resolution 9 bits

Conversion Time (Note 6) 100 ms

I2C inactive 0.25 0.5 mA

Shutdown mode, +VS = 3V 3Quiescent Supply Current

Shutdown mode, +VS = 5V 5 µA

+VS Supply Voltage Range 3.0 5.5 V

OS Output Saturation Voltage IOUT = 4.0mA (Note 7) 0.8 V

OS Delay (Note 8) 1 6 Conver-

sions

TOS Default Temperature (Note 9) 80 °C

THYST Default Temperature (Note 9) 75 °C

LOGIC (SDA, SCL, A0, A1, A2)

Input High Voltage VIH +VS x

0.7 V

Input Low Voltage VIL +VS x

0.3 V

Input High Current IIH VIN = 5V 0.005 1.0 µA

Input Low Current IIL VIN = 0V 0.005 1.0 µA

Input Capacitance All digital inputs 5 pF

Output High Current VIN = 5V 1 µA

Output Low Voltage IOL = 3mA 0.4 V

MAX7500–MAX7504

Digital Temperature Sensors and Thermal

Watchdog with Bus Lockup Protection

_______________________________________________________________________________________ 3

Note 4: All parameters are measured at +25°C. Values over the temperature range are guaranteed by design.

Note 5: There are no industry-wide standards for temperature accuracy specifications. These values allow comparison to ven-

dors who use 3-σlimits.

Note 6: This specification indicates how often temperature data is updated. The devices can be read at any time without regard

to conversion state, while yielding the last conversion result.

Note 7: For best accuracy, minimize output loading. Higher sink currents can affect sensor accuracy due to internal heating.

Note 8: OS delay is user programmable up to six “over-limit” conversions before OS is set to minimize false tripping in noisy

environments.

Note 9: Default values set at power-up.

Note 10: All timing specifications are guaranteed by design.

Note 11: A master device must provide a hold time of at least 300ns for the SDA signal to bridge the undefined region of SCL’s

falling edge.

Note 12: CB= total capacitance of one bus line in pF. Tested with CB= 400pF.

Note 13: Input filters on SDA, SCL, and A_ suppress noise spikes less than 50ns.

Note 14: Holding the SDA line low for a time greater than tTIMEOUT causes the devices to reset SDA to the IDLE state of the serial

bus communication (SDA set high).

ELECTRICAL CHARACTERISTICS (continued)

(+VS = +3.0V to +5.5V, TA= -55°C to +125°C, unless otherwise noted. Typical values are at +VS= +5V, TA= +25°C.) (Notes 4, 5)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

I2C-COMPATIBLE TIMING (Note 10)

Serial Clock Frequency fSCL Bus timeout inactive DC 400 kHz

Minimum RESET Pulse Width 1 µs

Bus Free Time Between STOP

and START Conditions tBUF 1.3 µs

START Condition Hold Time tHD:STA 0.6 µs

STOP Condition Setup Time tSU:STO 90% of SCL to 10% of SDA 100 ns

Clock Low Period tLOW 1.3 µs

Clock High Period tHIGH 0.6 µs

START Condition Setup Time tSU:STA 90% of SCL to 90% of SDA 100 ns

Data Setup Time tSU:DAT 10% of SDA to 10% of SCL 100 ns

Data Hold Time tHD:DAT 10% of SCL to 10% of SDA (Note 11) 0 0.9 µs

Maximum Receive SCL/SDA Rise

Time tR300 ns

Minimum Receive SCL/SDA Rise

Time tR(Note 12)

20 +

0.1 x

Maximum Receive SCL/SDA Fall

Time tF300 ns

Minimum Receive SCL/SDA Fall

Time tF(Note 12)

20 +

0.1 x

Transmit SDA Fall Time tF(Note 12)

20 +

0.1 x

250 ns

Pulse Width of Suppressed Spike tSP (Note 13) 0 50 ns

SDA Time Low for Reset of Serial

Interface tTIMEOUT MAX7500/MAX7501/MAX7502 (Note 14) 150 300 ms

MAX7500–MAX7504

Digital Temperature Sensors and Thermal

Watchdog with Bus Lockup Protection

4 _______________________________________________________________________________________

Typical Operating Characteristics

(TA = +25°C, unless otherwise noted.)

QUIESCENT SUPPLY CURRENT

vs. TEMPERATURE

MAX7500 toc01

TEMPERATURE (°C)

QUIESCENT SUPPLY CURRENT (μA)

9565355-25

240

250

260

270

280

290

300

230

-55 125

+VS = +5V

+VS = +3V

SHUTDOWN SUPPLY CURRENT (μA)

SHUTDOWN SUPPLY CURRENT

vs. TEMPERATURE

MAX7500 toc02

TEMPERATURE (°C)

9565355-25-55 125

+VS = +5V

+VS = +3V

ACCURACY vs. TEMPERATURE

ACCURACY (°C)

-1.5

-1.0

-0.5

0.5

1.0

1.5

2.0

-2.0

MAX7500 toc03

TEMPERATURE (°C)

9565355-25-55 125

4 TYPICAL PARTS

Pin Description

MAX7500 MAX7501–

MAX7504

NAME FUNCTION

1 1 SDA Serial Data Input/Output Line. Open drain. Connect SDA to a pullup resistor.

2 2 SCL Serial Data Clock Input. Open drain. Connect SCL to a pullup resistor.

3 3 OS Overtemperature Shutdown Output. Open drain. Connect OS to a pullup resistor.

4 4 GND Ground

5—A2

2-Wire Interface Address Input. Connect A2 to GND or +VS to set the desired I2C bus

address. Do not leave unconnected (see Table 1).

—5RESET Active-Low Reset Input. Pull RESET low for longer than the minimum reset pulse width

to reset the I2C bus and all internal registers to their POR values.

66A1

2-Wire Interface Address Input. Connect A1 to GND or +VS to set the desired I2C bus

address. Do not leave unconnected (see Table 1).

77A0

2-Wire Interface Address Input. Connect A0 to GND or +VS to set the desired I2C bus

address. Do not leave unconnected (see Table 1).

88+V

SPositive Supply Voltage Input. Bypass to GND with a 0.1µF bypass capacitor.

Detailed Description

The MAX7500–MAX7504 temperature sensors measure

temperature, convert the data into digital form using a

sigma-delta ADC, and communicate the conversion

results through an I2C-compatible 2-wire serial inter-

face. These devices accept standard I2C commands to

read the data, set the overtemperature alarm (OS) trip

thresholds, and configure other characteristics. The

MAX7500 features three address select lines (A0, A1,

A2) while the MAX7501–MAX7504 feature two address

select lines (A0, A1) and a RESET input. The

MAX7500–MAX7504 operate from +3.0V to +5.5V sup-

ply voltages and consume 250µA of supply current.

MAX7500–MAX7504

Digital Temperature Sensors and Thermal

Watchdog with Bus Lockup Protection

_______________________________________________________________________________________ 5

I2C-Compatible Bus Interface

From a software perspective, the MAX7500–MAX7504

appear as a set of byte-wide registers that contain tem-

perature data, alarm threshold values, and control bits.

A standard I2C-compatible 2-wire serial interface reads

temperature data and writes control bits and alarm

threshold data. Each device responds to its own I2C

slave address, which is selected using A0, A1, and A2.

See Table 1.

The MAX7500–MAX7504 employ four standard I2C

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

byte (Figures 1, 2, and 3). The shorter receive byte pro-

tocol allows quicker transfers, provided that the correct

data register was previously selected by a read-byte

instruction. Use caution when using the shorter proto-

cols in multimaster systems, as a second master could

overwrite the command byte without informing the first

master. The MAX7500 has eight different slave

addresses available; therefore, a maximum of eight

MAX7500 devices can share the same bus. The

MAX7501–MAX7504 each have four different slave

addresses available.

DEVICE BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0

MAX7500 1 0 0 1 A2 A1 A0 RD/W

MAX7501 1 0 0 1 1 A1 A0 RD/W

MAX7502 1 0 0 1 0 A1 A0 RD/W

MAX7503 1 0 0 1 1 A1 A0 RD/W

MAX7504 1 0 0 1 0 A1 A0 RD/W

Table 1. I2C Slave Addresses

tBUF

tSU:STO

tHD:STA

tSU:STA

tHD:DAT

tHIGH

tLOW

tSU:DAT

tHD:STA

SCL

SDA

ACKNOWLEDGE

(A)

STOP

CONDITION

(P)

START

CONDITION

(S)

START

CONDITION

(S)

REPEATED START

CONDITION

(SR)

PARAMETERS ARE MEASURED FROM 10% TO 90%.

Figure 1. Serial Bus Timing

MAX7500–MAX7504

Digital Temperature Sensors and Thermal

Watchdog with Bus Lockup Protection

6 _______________________________________________________________________________________

ADDRESS

BYTE

ADDRESS

BYTE

ADDRESS

BYTE

(a) TYPICAL POINTER SET FOLLOWED BY IMMEDIATE READ FROM CONFIGURATION REGISTER

(b) CONFIGURATION REGISTER WRITE

POINTER

BYTE

POINTER

BYTE

POINTER

BYTE MOST-SIGNIFICANT

DATA BYTE

LEAST-SIGNIFICANT

DATA BYTE

CONFIGURATION

BYTE

ADDRESS

BYTE

DATA

BYTE

ACK BY

MAX7500–

MAX7504

ACK BY

MAX7500–

MAX7504

ACK BY

MAX7500–

MAX7504 ACK BY

MAX7500–

MAX7504

ACK BY

MAX7500–

MAX7504

ACK BY

MAX7500–

MAX7504

ACK BY

MAX7500–

MAX7504

START

MASTER

START

MASTER

START

MASTER

REPEAT

START

MASTER

ACK BY

MASTER

STOP

COND BY

MASTER

ACK BY

MAX7500–

MAX7504

ACK BY

MAX7500–

MAX7504

STOP

COND BY

MASTER

STOP

COND BY

MASTER

ACK BY

MAX7500–

MAX7504

Figure 2. I2C-Compatible Timing Diagram (Write)

MAX7500–MAX7504

Digital Temperature Sensors and Thermal

Watchdog with Bus Lockup Protection

_______________________________________________________________________________________ 7

ADDRESS

BYTE

ADDRESS BYTE

ADDRESS

BYTE

ADDRESS

BYTE

DATA

BYTE

(a) TYPICAL 2-BYTE READ FROM PRESET POINTER LOCATION SUCH AS TEMP, THIGH, TLOW.

(b) TYPICAL POINTER SET FOLLOWED BY IMMEDIATE READ FOR 2-BYTE REGISTER SUCH AS TEMP, THIGH, TLOW.

MOST-SIGNIFICANT

DATA BYTE

LEAST-SIGNIFICANT

DATA BYTE

POINTER BYTE

MOST-SIGNIFICANT

DATA BYTE

LEAST-SIGNIFICANT

DATA BYTE

ACK BY

MAX7500–

MAX7504

ACK BY

MASTER

ACK BY

MAX7500–

MAX7504

ACK BY

MAX7500–

MAX7504

ACK BY

MASTER

ACK BY

MAX7500–

MAX7504

ACK BY

MASTER

START

MASTER

START

MASTER

REPEAT

START

MASTER

START

MASTER

STOP

COND BY

MASTER

STOP

COND BY

MASTER

STOP

COND BY

MASTER

NO ACK BY

MASTER

ACK BY

MASTER

ACK BY

MASTER

Figure 3. I2C-Compatible Timing Diagram (Read)

MAX7500–MAX7504

The MAX7500–MAX7504 have an internal pnp-junction-

based temperature sensor whose analog output is con-

verted to digital form using a 9-bit sigma-delta ADC.

The measured temperature and temperature configura-

tions are controlled by the temperature, configuration,

THYST, and TOS registers. See Table 2.

Temperature Register

Read the measured temperature through the tempera-

ture register. The temperature data format is 9 bits,

two’s complement, and the register is read out in 2

bytes: an upper byte and a lower byte. Bit D15 is the

sign bit. When bit D15 is 1, the temperature reading is

negative. When bit D15 is zero, the temperature read-

ing is positive. Bits D14–D7 contain the temperature

data, with the LSB representing 0.5°C and the MSB

representing 64°C (see Table 3). The MSB is transmit-

ted first. The last 7 bits of the lower byte, bits D6–D0,

are don’t cares. When reading the temperature register,

bits D6–D0 must be ignored. When the measured tem-

perature is greater than +127.5°C, the value stored in

the temperature register is clipped to 7F8h. When the

measured temperature is below -64°C, the value in the

temperature register is clipped to BF8h.

During the time of reading the temperature register, any

changes in temperature are ignored until the read is

completed. The temperature register is updated upon

completion of the next conversion.

Table 3 lists the temperature register definition.

Configuration Register

The 8-bit configuration register sets the fault queue, OS

polarity, shutdown control, and whether the OS output

functions in comparator or interrupt mode. When writing

to the configuration register, set bits D7, D6, and D5 to

zero. See Table 5.

Bits D4 and D3, the fault queue bits, determine the

number of faults necessary to trigger an OS condition.

See Table 6. The number of faults set in the queue must

occur to trip the OS output. The fault queue prevents

OS false tripping in noisy environments.

Set bit D2, the OS polarity bit, to zero to force the OS

output active low. Set bit D2 to 1 to set the OS output

polarity to active high. OS is an open-drain output

under all conditions and requires a pullup resistor to

output a high voltage. See Figure 4.

Set bit D1, the comparator/interrupt bit to zero to run

the overtemperature shutdown block in comparator

mode. In comparator mode, OS is asserted when the

temperature rises above the TOS value. OS is deassert-

ed when the temperature drops below the THYST value.

Digital Temperature Sensors and Thermal

Watchdog with Bus Lockup Protection

8 _______________________________________________________________________________________

(BINARY) POR STATE (°C) READ/

WRITE

Temperature 00 — — — Read only

Configuration 01 00 0000 0000 — R/W

THYST 02 4B0 0100 1011 0 75 R/W

TOS 03 500 0101 0000 0 80 R/W

Table 2. Register Functions

UPPER BYTE LOWER BYTE

D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0

Sign bit

1= Negative

0 = Positive

MSB

64°C32°C16°C8°C4°C2°C1°CLSB

0.5°CXXXXXXX

DIGITAL OUTPUT

TEMPERATURE (°C) BINARY hex

+125 0111 1101 0xxx xxxx 7D0x

+25 0001 1001 0xxx xxxx 190x

+0.5 0000 0000 1xxx xxxx 008x

0 0000 0000 0xxx xxxx 000x

-0.5 1111 1111 1xxx xxxx FF8x

-25 1110 0111 0xxx xxxx E70x

-55 1100 1001 0xxx xxxx C90x

Table 3. Temperature Register Definition

Table 4. Temperature Data Output

X = Don’t care.

See Figure 4. Set bit D1 to 1 to run the overtemperature

shutdown block in interrupt mode. OS is asserted in

interrupt mode when the temperature rises above the

TOS value or falls below the THYST value. OS is

deasserted only after performing a read operation.

Set bit D0, the shutdown bit, to zero for normal opera-

tion. Set bit D0 to 1 to shut down the MAX7500–

MAX7504 internal blocks, dropping the supply current

to 3µA. The I2C interface remains active as long as the

shutdown bit is set. The TOS, THYST, and configuration

registers can still be written to and read from while in

shutdown.

and T

HYST

Registers

In comparator mode, the OS output behaves like a ther-

mostat. The output asserts when the temperature rises

above the limit set in the TOS register. The output

deasserts when the temperature falls below the limit set

in the THYST register. In comparator mode, the OS output

can be used to turn on a cooling fan, initiate an emer-

gency shutdown signal, or reduce system clock speed.

In interrupt mode, exceeding TOS also asserts OS. OS

remains asserted until a read operation is performed on

any of the registers. Once OS has asserted due to

crossing above TOS and is then reset, it is asserted

again only when the temperature drops below THYST.

The output remains asserted until it is reset by a read.

Putting the MAX7500–MAX7504 into shutdown mode

also resets OS.

The TOS and THYST registers are accessed with 2

bytes, with bits D15–D7 containing the data. Bits

D6–D0 are don’t cares when writing to these two regis-

ters and read-back zeros when reading from these reg-

isters. The LSB represents 0.5°C while the MSB

represents 64°C. See Table 7.

MAX7500–MAX7504

Digital Temperature Sensors and Thermal

Watchdog with Bus Lockup Protection

_______________________________________________________________________________________ 9

D7 D6 D5 D4 D3 D2 D1 D0

0 0 0 Fault queue Fault queue OS polarity Comparator/

interrupt Shutdown

Table 5. Configuration Register Definition

D4 D3 NO. OF FAULTS

0 0 1 (POR state)

01 2

10 4

11 6

Table 6. Configuration Register Fault

Queue Bits

TOS

THYST

OS OUTPUT

(COMPARATOR MODE)

OS SET ACTIVE LOW

OS OUTPUT

(INTERRUPT MODE)

OS SET ACTIVE LOW READ

OPERATION

READ

OPERATION

READ

OPERATION

TEMPERATURE

Figure 4. OS Timing Diagram

UPPER BYTE LOWER BYTE

COMMAND D15 D14 D13 D12 D11 D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 D0

Write

Sign bit

1 = negative

0 = positive

MSB

64°C32°C16°C8°C4°C2°C1°CLSB

0.5°CXXXX X XX

Read

Sign bit

1 = negative

0 = positive

MSB

64°C32°C16°C8°C4°C2°C1°CLSB

0.5°C0000 0 00

Table 7. TOS and THYST Register Definitions

X = Don’t care.

MAX7500–MAX7504

Shutdown

Set bit D0 in the configuration register to 1 to place the

MAX7500–MAX7504 in shutdown mode and reduce

supply current to 3µA.

Power-Up and Power-Down

The MAX7500–MAX7504 power up to a known state, as

indicated in Table 2. Some of these settings are sum-

marized below:

• Comparator mode

•T

OS = +80°C

•T

HYST = +75°C

• OS active low

• Pointer = 00

Internal Registers

The MAX7500–MAX7504s’ pointer register selects

between four data registers. See Figure 5. At power-up,

the pointer is set to read the temperature register at

address 00. The pointer register latches the last loca-

tion to which it was set. All registers are read and write,

except the temperature register, which is read only.

Write to the configuration register by writing an address

byte, a data pointer byte, and a data byte. If 2 data

bytes are written, the second data byte overrides the

first. If more than 2 data bytes are written, only the first

2 bytes are recognized while the remaining bytes are

ignored. The TOS and THYST registers require 1

address byte and 1 pointer byte and 2 data bytes. If

only 1 data byte is written, it is saved in bits D15–D8 of

the respective register. If more than 2 data bytes are

written, only the first 2 bytes are recognized while the

remaining bytes are ignored.

Read from the MAX7500–MAX7504 in one of two ways.

If the location latched in the pointer register is set from

the previous read, the new read consists of an address

byte, followed by retrieving the corresponding number

of data bytes. If the pointer register needs to be set to a

new address, perform a read operation by writing an

address byte, pointer byte, repeat start, and another

address byte.

An inadvertent 8-bit read from a 16-bit register, with the

D7 bit low, can cause the MAX7500–MAX7504 to stop

in a state where the SDA line is held low. Ordinarily, this

would prevent any further bus communication until the

master sends nine additional clock cycles or SDA goes

high. At that time, a stop condition resets the device.

With the MAX7500/MAX7501/MAX7502, if the additional

clock cycles are not generated by the master, the bus

resets and unlocks after the bus timeout period has

elapsed.

The MAX750–MAX7504 can be reset by pulsing RESET

low.

Bus Timeout

Communication errors sometimes occur due to noise

pickup on the bus. In the worst case, such errors can

cause the slave device to hold the data line low, there-

by preventing other devices from communicating over

the bus. The MAX7500/MAX7501/MAX7502s’ internal

bus timeout circuit resets the bus and releases the data

line if the line is low for more than 250ms. When the bus

timeout is active, the minimum serial clock frequency is

limited to 6Hz.

RESET

The RESET input on the MAX7503/MAX7504 provides a

way to reset the I2C bus and all the internal registers to

their initial POR values. To reset, apply a low pulse with

a duration of at least 1µs to the RESET input.

Digital Temperature Sensors and Thermal

Watchdog with Bus Lockup Protection

10 ______________________________________________________________________________________

MAX7504

+VS

A2/RESET

SDA

SCL OS

SMBus

INTERFACE

BLOCK

POINTER REGISTER

(SELECTS REGISTER

FOR COMMUNICATION)

DATA ADDRESS

GND

TEMPERATURE

(READ ONLY)

POINTER = 0000 0000

TOS SET POINT

(READ/WRITE)

POINTER = 0000 0011

THYST SET POINT

(READ/WRITE)

POINTER = 0000 0010

CONFIGURATION

(READ/WRITE)

POINTER = 0000 0001

Figure 5. Block Diagram

Applications Information

Digital Noise

The MAX7500–MAX7504 feature an integrated lowpass

filter on both the SCL and the SDA digital lines to miti-

gate the effects of bus noise. Although this filtering

makes communication robust in noisy environments,

good layout practices are always recommended.

Minimize noise coupling by keeping digital traces away

from switching power supplies. Ensure that digital lines

containing high-speed data communications cross at

right angles to the SDA and SCL lines.

Excessive noise coupling into the SDA and SCL lines

on the MAX7500–MAX7504—specifically noise with

amplitude greater than 400mVP-P (the MAX7500–

MAX7504s’ typical hysteresis), overshoot greater than

300mV above +VS, and undershoot more than 300mV

below GND—may prevent successful serial communi-

cation. Serial bus no-acknowledge is the most common

symptom, causing unnecessary traffic on the bus.

Care must be taken to ensure proper termination within

a system with long PCB traces or multiple parts on the

bus. Resistance can be added in series with the SDA

and SCL lines to further help filter noise and ringing. If it

proves to be necessary, a 5kΩresistor should be

placed in series with the SCL line, placed as close as

possible to SCL. This 5kΩresistor, with the 5pF to 10pF

stray capacitance of the MAX7500–MAX7504 provide a

6MHz to 12MHz lowpass filter, which is sufficient filter-

ing in most cases.

Chip Information

PROCESS: CMOS

MAX7500–MAX7504

Digital Temperature Sensors and Thermal

Watchdog with Bus Lockup Protection

______________________________________________________________________________________ 11

Ordering Information/

Selector Guide (continued)

PART TEMP

RANGE

PIN-

PACKAGE RESET TIMEOUT

MAX7500MSA+ -55°C to

+125°C 8 SO X X

MAX7500MUA -55°C to

+125°C 8 µMAX X X

MAX7500MUA+ -55°C to

+125°C 8 µMAX X X

MAX7501MSA -55°C to

+125°C 8 SO X X

MAX7501MSA+ -55°C to

+125°C 8 SO X X

MAX7501MUA -55°C to

+125°C 8 µMAX X X

MAX7501MUA+ -55°C to

+125°C 8 µMAX X X

MAX7502MSA -55°C to

+125°C 8 SO X —

MAX7502MSA+ -55°C to

+125°C 8 SO X —

MAX7502MUA -55°C to

+125°C 8 µMAX X —

MAX7502MUA+ -55°C to

+125°C 8 µMAX X —

MAX7503MSA -55°C to

+125°C 8 SO X —

MAX7503MSA+ -55°C to

+125°C 8 SO X —

MAX7503MUA -55°C to

+125°C 8 µMAX X —

MAX7503MUA+ -55°C to

+125°C 8 µMAX X —

MAX7504MSA -55°C to

+125°C 8 SO X —

MAX7504MSA+ -55°C to

+125°C 8 SO X —

MAX7504MUA -55°C to

+125°C 8 µMAX X —

MAX7504MUA+ -55°C to

+125°C 8 µMAX X —

Denotes a lead(Pb)-free/RoHS-compliant package.

+VS

A2GND

SCL

SDA

MAX7500

μMAX, SO

+VS

RESETGND

SCL

SDA

MAX7501–

MAX7504

μMAX, SO

TOP VIEW

Pin Configurations

MAX7500–MAX7504

Digital Temperature Sensors and Thermal

Watchdog with Bus Lockup Protection

12 ______________________________________________________________________________________

PACKAGE TYPE PACKAGE CODE OUTLINE NO. LAND PATTERN NO.

8 SO S8-2 21-0041 90-0096

8 µMAX U8-1 21-0036 90-0092

Package Information

For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the

package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the

package regardless of RoHS status.

MAX7500–MAX7504

Digital Temperature Sensors and Thermal

Watchdog with Bus Lockup Protection

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.

Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________

Revision History

REVISION

NUMBER

REVISION

DATE DESCRIPTION PAGES

CHANGED

0 8/04 Initial release of MAX7500 —

1 10/04 Initial release of MAX7501/MAX7502 All

2 6/05 Initial release of MAX7503/MAX7504 All

3 8/08

Various corrections and edits to clarify specifications; added Typical Application

Circuits 1–4, 11, 12, 13

4 10/10

Removed the UL certified bullet from the Features section as the parts have never

been certified 1