MAXIM MAX7504 User Manual

General Description

The MAX7500–MAX7504 temperature sensors accu­rately measure temperature and provide an overtem­perature alarm/interrupt/shutdown output. These
devices convert the temperature measurements to digi­tal form using a high-resolution, sigma-delta, analog-to­digital 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 I

2

C-com­patible interface make them ideal for a wide range of
applications, including personal computers (PCs), elec­tronic 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

♦ I

2

C 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

1

Ordering Information/

Selector Guide

19-3382; Rev 4; 10/10

EVALUATION KIT

AVAILABLE

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.

Typical Application Circuits

PART

MAX7500MSA

TEMP

RANGE

-55°C to
+125°C

PIN­PACKAGE

8 SO X X

RESET TIMEOUT

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

TO I

4.7kΩ

2

C MASTER

SDA

SCL

GND

+V

S

A0

MAX7501

OS

MAX7502
MAX7503
MAX7504

A1

RESET

4.7kΩ

+V

SDA

TO I2C MASTER

SCL

GND

OS

MAX7500

S

A0

A1

A2

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 (V

I

) at any pin exceeds the power supplies (VI< V

GND

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 1.5kΩ resistor.

(Note 1)
+V

S

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

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

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

S

+ 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 (T

A

= +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

Accuracy, 6-σ

Accuracy, 3-σ (Note 5)

Resolution 9 bits

Conversion Time (Note 6) 100 ms

+VS Supply Voltage Range 3.0 5.5 V

OS Output Saturation Voltage I

OS Delay (Note 8) 1 6

TOS Default Temperature (Note 9) 80 °C

T

HYST

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

Input High Voltage V

Input Low Voltage V

Input High Current I

Input Low Current I

Input Capacitance All digital inputs 5 pF

Output High Current VIN = 5V 1 µA

Output Low Voltage IOL = 3mA 0.4 V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

-25°C ≤ TA ≤ +100°C -2.0 ±2.0

-55°C ≤ T

-25°C ≤ TA ≤ +100°C -1.5 +1.5

-55°C ≤ T

I2C inactive 0.25 0.5 mA

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

Shutdown mode, +V

OUT

Default Temperature (Note 9) 75 °C

IH

IL

IH

IL

VIN = 5V 0.005 1.0 µA

VIN = 0V 0.005 1.0 µA

A

A

= 4.0mA (Note 7) 0.8 V

≤ +125°C -3.0 ±3.0

≤ +125°C -2.0 +2.0

= 5V 5

S

+VS x

0.7
+VS x

0.3

°C

°C

µA

Conver-

sions

V

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-σ limits.

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: C

B

= 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 t

TIMEOUT

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 f
Minimum RESET Pulse Width 1 µs

Bus Free Time Between STOP
and START Conditions

START Condition Hold Time t

STOP Condition Setup Time t

Clock Low Period t

Clock High Period t

START Condition Setup Time t

Data Setup Time t

Data Hold Time t

Maximum Receive SCL/SDA Rise
Time

Minimum Receive SCL/SDA Rise
Time

Maximum Receive SCL/SDA Fall
Time

Minimum Receive SCL/SDA Fall
Time

Transmit SDA Fall Time t

Pulse Width of Suppressed Spike t

SDA Time Low for Reset of Serial
Interface

SCL

t

BUF

HD:STA

SU:STO

LOW

HIGH

SU:STA

SU:DAT

HD:DAT

t

t

t

t

SP

t

TIMEOUT

Bus timeout inactive DC 400 kHz

1.3 µs

0.6 µs

90% of SCL to 10% of SDA 100 ns

1.3 µs

0.6 µs

90% of SCL to 90% of SDA 100 ns

10% of SDA to 10% of SCL 100 ns

10% of SCL to 10% of SDA (Note 11) 0 0.9 µs

R

(Note 12)

R

F

(Note 12)

F

20 +

(Note 12)

F

(Note 13) 0 50 ns

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

0.1 x
C

300 ns

20 +

0.1 x
C

B

300 ns

20 +

0.1 x
C

B

B

250 ns

ns

ns

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)

1

2

3

4

5

6

0

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

0.5

1.0

1.5

2.0

-2.0

MAX7500 toc03

TEMPERATURE (°C)

9565355-25-55 125

4 TYPICAL PARTS

Pin Description

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 inter­face. 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 sup­ply voltages and consume 250µA of supply current.

PIN

MAX7500

MAX7501–

MAX7504

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

—5RESET

66A1

77A0

88+V

NAME FUNCTION

2-Wire Interface Address Input. Connect A2 to GND or +V
address. Do not leave unconnected (see Table 1).

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

2

to reset the I

C bus and all internal registers to their POR values.

2-Wire Interface Address Input. Connect A1 to GND or +V
address. Do not leave unconnected (see Table 1).

2-Wire Interface Address Input. Connect A0 to GND or +V
address. Do not leave unconnected (see Table 1).

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

S

to set the desired I2C bus

S

to set the desired I2C bus

S

to set the desired I2C bus

S

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 tem­perature 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 pro­tocol allows quicker transfers, provided that the correct
data register was previously selected by a read-byte
instruction. Use caution when using the shorter proto­cols 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.

Table 1. I2C Slave Addresses

Figure 1. Serial Bus Timing

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

SDA

t

STOP

(P)

BUF

START

CONDITION

(S)

t

SU:DAT

t

LOW

SCL

t

HIGH

t

HD:STA

t

R

START

CONDITION

(S)

PARAMETERS ARE MEASURED FROM 10% TO 90%.

t

t

HD:DAT

t

F

SU:STA

REPEATED START

CONDITION

(SR)

t

HD:STA

ACKNOWLEDGE

(A)

t

SU:STO

CONDITION

MAX7500–MAX7504

Digital Temperature Sensors and Thermal
Watchdog with Bus Lockup Protection

6 _______________________________________________________________________________________

Figure 2. I2C-Compatible Timing Diagram (Write)

STOP

MASTER

COND BY

NO

ACK BY

ACK BY

MASTER

BYTE

DATA

MAX7504

MAX7500–

STOP

MASTER

COND BY

ACK BY

MAX7504

MAX7500–

STOP

COND BY

MASTER

ACK BY

MAX7504

MAX7500–

DATA BYTE

LEAST-SIGNIFICANT

ACK BY

MAX7504

MAX7500–

BYTE

ADDRESS

START

REPEAT

ACK BY

MAX7500–

BY

MASTER

MAX7504

BYTE

CONFIGURATION

ACK BY

MAX7504

MAX7500–

DATA BYTE

MOST-SIGNIFICANT

ACK BY

MAX7504

MAX7500–

(b) CONFIGURATION REGISTER WRITE

WRITE

LOW

AND T

HIGH

(c) T

ACK BY

START

BYTE

POINTER

MAX7504

MAX7500–

BYTE

ADDRESS

BY

MASTER

BYTE

POINTER

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

ACK BY

MAX7504

MAX7500–

BYTE

ADDRESS

BY

START

MASTER

BY

START

BYTE

POINTER

ACK BY

MAX7500–

BYTE

ADDRESS

MASTER

MAX7504

MAX7500–MAX7504

Digital Temperature Sensors and Thermal

Watchdog with Bus Lockup Protection

_______________________________________________________________________________________ 7

Figure 3. I2C-Compatible Timing Diagram (Read)

STOP

MASTER

COND BY

NO

ACK BY

MASTER

STOP

MASTER

COND BY

MASTER

NO ACK BY

DATA BYTE

LEAST-SIGNIFICANT

.

LOW

MASTER

, T

HIGH

STOP

MASTER

COND BY

NO

ACK BY

MASTER

.

LOW

DATA BYTE

, T

HIGH

LEAST-SIGNIFICANT

ACK BY

MASTER

ACK BY

MAX7500–

ACK BY

MAX7504

DATA BYTE

MOST-SIGNIFICANT

ACK BY

MAX7504

MAX7500–

BYTE

ADDRESS

BY

START

MASTER

POINTER BYTE

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

ACK BY

MASTER

ADDRESS BYTE

BY

START

MASTER

START

REPEAT

DATA BYTE

MOST-SIGNIFICANT

ACK BY

MAX7504

MAX7500–

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

BYTE

ADDRESS

BY

MASTER

START

ACK BY

BY

BYTE

DATA

(c) TYPICAL 1-BYTE READ FROM CONFIGURATION REGISTER WITH PRESET POINTER.

MAX7504

MAX7500–

BYTE

ADDRESS

MASTER

MAX7500–MAX7504

Register Descriptions

The MAX7500–MAX7504 have an internal pnp-junction­based temperature sensor whose analog output is con­verted to digital form using a 9-bit sigma-delta ADC.
The measured temperature and temperature configura­tions are controlled by the temperature, configuration,
T

HYST

, and TOSregisters. See Table 2.

Temperature Register

Read the measured temperature through the tempera­ture 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 read­ing 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 transmit­ted 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 tem­perature 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 TOSvalue. OS is deassert­ed when the temperature drops below the T

HYST

value.

Digital Temperature Sensors and Thermal
Watchdog with Bus Lockup Protection

8 _______________________________________________________________________________________

Table 2. Register Functions

Table 3. Temperature Register Definition

Table 4. Temperature Data Output

X = Don’t care.

REGISTER NAME ADDRESS (HEX) POR STATE (HEX)

Temperature 00 — — — Read only
Configuration 01 00 0000 0000 — R/W

T

HYST

T

OS

02 4B0 0100 1011 0 75 R/W
03 500 0101 0000 0 80 R/W

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°C

32°C16°C8°C4°C2°C1°C

TEMPERATURE (°C)

[phone]xxx xxxx 7D0x

[phone]xxx 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

DIGITAL OUTPUT

BINARY hex

POR STATE

(BINARY)

LSB

0.5°C

POR STATE (°C)

XXXXXXX

READ/
WRITE

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
TOSvalue or falls below the T

HYST

value. OS is

deasserted only after performing a read operation.

Set bit D0, the shutdown bit, to zero for normal opera­tion. 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, T

HYST

, and configuration
registers can still be written to and read from while in
shutdown.

TOSand T

HYST

Registers

In comparator mode, the OS output behaves like a ther­mostat. The output asserts when the temperature rises
above the limit set in the TOSregister. The output
deasserts when the temperature falls below the limit set
in the T

HYST

register. In comparator mode, the OS output
can be used to turn on a cooling fan, initiate an emer­gency shutdown signal, or reduce system clock speed.

In interrupt mode, exceeding T

OS

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 TOSand is then reset, it is asserted
again only when the temperature drops below T

HYST

.
The output remains asserted until it is reset by a read.
Putting the MAX7500–MAX7504 into shutdown mode
also resets OS.

The TOSand T

HYST

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 regis­ters and read-back zeros when reading from these reg­isters. 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

Table 5. Configuration Register Definition

Table 6. Configuration Register Fault
Queue Bits

Figure 4. OS Timing Diagram

Table 7. TOSand T

HYST

Register Definitions

X = Don’t care.

D7 D6 D5 D4 D3 D2 D1 D0

0 0 0 Fault queue Fault queue OS polarity

D4 D3 NO. OF FAULTS

0 0 1 (POR state)

01 2

10 4

11 6

Comparator/

T

OS

TEMPERATURE

T

HYST

OS OUTPUT

(COMPARATOR MODE)

OS SET ACTIVE LOW

OS OUTPUT

(INTERRUPT MODE)

OS SET ACTIVE LOW

READ

OPERATION

interrupt

READ

OPERATION

Shutdown

READ

OPERATION

COMMAND

Write

Read

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

Sign bit

1 = negative

0 = positive

Sign bit

1 = negative

0 = positive

MSB

64°C

MSB
64°C

UPPER BYTE LOWER BYTE

32°C16°C8°C4°C2°C1°C

32°C16°C8°C4°C2°C1°C

LSB

0.5°C

LSB

0.5°C

XXXX X XX

0000 0 00

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 sum­marized below:

• Comparator mode

•TOS= +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 loca­tion 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 TOSand T

HYST

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, there­by 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 ______________________________________________________________________________________

Figure 5. Block Diagram

+V

SET POINT

OS

DATA

S

SMBus

INTERFACE

BLOCK

ADDRESS

POINTER REGISTER

(SELECTS REGISTER

FOR COMMUNICATION)

REGISTER SELECT

GND

A0
A1

A2/RESET

SDA

SCL

TEMPERATURE

(READ ONLY)

POINTER = 0000 0000

T
(READ/WRITE)

POINTER = 0000 0011

MAX7504

CONFIGURATION

(READ/WRITE)

POINTER = 0000 0001

SET POINT

T

HYST

(READ/WRITE)

POINTER = 0000 0010

OS

Applications Information

Digital Noise

The MAX7500–MAX7504 feature an integrated lowpass
filter on both the SCL and the SDA digital lines to miti­gate 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 400mV

P-P

(the MAX7500–
MAX7504s’ typical hysteresis), overshoot greater than
300mV above +V

S

, and undershoot more than 300mV
below GND—may prevent successful serial communi­cation. 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 5kΩ resistor should be
placed in series with the SCL line, placed as close as
possible to SCL. This 5kΩ resistor, with the 5pF to 10pF
stray capacitance of the MAX7500–MAX7504 provide a
6MHz to 12MHz lowpass filter, which is sufficient filter­ing 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)

+

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

1

2

3

4

8

7

6

5

+V

S

A0

A1

A2GND

OS

SCL

SDA

MAX7500

μMAX, SO

1

2

3

4

8

7

6

5

+V

S

A0

A1

RESETGND

OS

SCL

SDA

MAX7501–

MAX7504

μMAX, SO

TOP VIEW

Pin Configurations

PART

MAX7500MSA+

MAX7500MUA

MAX7500MUA+

MAX7501MSA

MAX7501MSA+

MAX7501MUA

MAX7501MUA+

MAX7502MSA

MAX7502MSA+

MAX7502MUA

MAX7502MUA+

MAX7503MSA

MAX7503MSA+

MAX7503MUA

MAX7503MUA+

MAX7504MSA

MAX7504MSA+

MAX7504MUA

MAX7504MUA+

TEMP

RANGE

-55°C to
+125°C

-55°C to
+125°C

-55°C to
+125°C

-55°C to
+125°C

-55°C to
+125°C

-55°C to
+125°C

-55°C to
+125°C

-55°C to
+125°C

-55°C to
+125°C

-55°C to
+125°C

-55°C to
+125°C

-55°C to
+125°C

-55°C to
+125°C

-55°C to
+125°C

-55°C to
+125°C

-55°C to
+125°C

-55°C to
+125°C

-55°C to
+125°C

-55°C to
+125°C

PIN­PACKAGE

8 SO X X

8 µMAX X X

8 µMAX X X

8 SO X X

8 SO X X

8 µMAX X X

8 µMAX X X

8 SO X —

8 SO X —

8 µMAX X —

8 µMAX X —

8 SO X —

8 SO X —

8 µMAX X —

8 µMAX X —

8 SO X —

8 SO X —

8 µMAX X —

8 µMAX X —

RESET TIMEOUT

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 ____________________

13

© 2010 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products.

Revision History

REVISION

NUMBER

0 8/04 Initial release of MAX7500 —

1 10/04 Initial relea se of MAX7501/MAX7502 Al l

2 6/05 Initial release of MAX7503/MAX7504 Al l

3 8/08

4 10/10

REVISION

DATE

DESCRIPTION

Various corrections and edits to clarify specifications; added Typical Application
Circuits

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

PAGES

CHANGED

1–4, 11, 12, 13

1