Page 1
General Description
The MAX7500/MAX7501/MAX7502 temperature sensors accurately measure temperature and provide an
over-temperature alarm/interrupt/shutdown output.
These devices convert the temperature measurements
to digital 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 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 over-temperature shutdown output.
The MAX7500 features three address select lines, while
the MAX7501 and MAX7502 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 I2Ccompatible interface make them ideal for a wide range
of applications, including personal computers (PCs),
electronic test equipment, and office electronics.
The MAX7500/MAX7501/MAX7502 are available in 8pin 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
♦ I2C Bus Interface
♦ 3.0V to 5.5V Supply Voltage Range
♦ 250µA (typ) Operating Supply Current
♦ 3µA (typ) Shutdown Supply Current
♦ ±2°C (max) from -25°C to +100°C Temperature
Accuracy
♦ 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/MAX7501/MAX7502
Digital Temperature Sensors and Thermal
Watchdog with Bus Lockup Protection
________________________________________________________________ Maxim Integrated Products 1
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
MAX7502
µMAX, SO
TOP VIEW
Pin Configurations
Ordering Information
19-3382; Rev 1; 10/04
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.
PART TEMP RANGE PIN-PACKAGE
MAX7500MSA -55°C to +125°C 8 SO
MAX7500MUA -55°C to +125°C 8 µMAX
MAX7501MSA -55°C to +125°C 8 SO
MAX7501MUA -55°C to +125°C 8 µMAX
MAX7502MSA -55°C to +125°C 8 SO
MAX7502MUA -55°C to +125°C 8 µMAX
Purchase of I2C components from Maxim Integrated Products
Inc., or one of its sublicensed Associated Companies, conveys
a license under Philips I
2
C Patent Rights to use these compo-
nents in an I
2
C system, provided that the system conforms to
the I
2
C Standard Specification as defined by Philips.
I
2
C is a trademark of Philips Corp.
µMAX is a registered trademark of Maxim Integrated
Products, Inc.
查询MAX7500供应商
Page 2
MAX7500/MAX7501/MAX7502
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< 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
PARAMETER
CONDITIONS
UNITS
-25°C ≤ TA ≤ +100°C
Accuracy
-55°C ≤ T
A
≤ +125°C
°C
Resolution 9 Bits
Conversion Time (Note 6)
ms
I2C inactive
0.5 mA
Shutdown mode, +VS = 3V 3Quiescent Supply Current
Shutdown mode, +V
S
= 5V 5
µA
+VS Supply Voltage Range 3.0 5.5 V
OS Output Saturation Voltage I
OUT
= 4.0mA (Note 7) 0.8 V
OS Delay (Note 8) 1 6
Conver-
sions
TOS Default Temperature (Note 9) 80 °C
T
HYST
Default Temperature (Note 9) 75 °C
LOGIC (SDA, SCL, A0, A1, A2)
Input High Voltage V
IH
+VS x
0.7
V
Input Low Voltage V
IL
+VS x
0.3
V
Input High Current I
IH
VIN = 5V
1.0 µA
Input Low Current I
IL
VIN = 0V
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
SYMBOL
MIN TYP MAX
±2.0
±3.0
100
0.25
0.005
0.005
Page 3
MAX7500/MAX7501/MAX7502
Digital Temperature Sensors and Thermal
Watchdog with Bus Lockup Protection
_______________________________________________________________________________________ 3
Note 4: All parts operate properly over the +VS= 3V to 5V supply voltage range. The devices are tested and specified for rated
accuracy at their nominal supply voltage. Accuracy typically degrades 1°C per volt of change in +V
S
as it varies from the
nominal value.
Note 5: All parameters are measured at +25°C. Values over the temperature range are guaranteed by design.
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
SCL
Bus timeout inactive DC 400 kHz
Minimum RESET Pulse Width 1 µs
Bus Free Time Between STOP
and START Conditions
t
BUF
1.3 µs
START Condition Hold Time t
HD:STA
0.6 µs
STOP Condition Setup Time t
SU:STO
90% of SCL to 10% of SDA 100 ns
Clock Low Period t
LOW
1.3 µs
Clock High Period t
HIGH
0.6 µs
START Condition Setup Time t
SU:STA
90% of SCL to 90% of SDA 100 ns
Data Setup Time t
SU:DAT
10% of SDA to 10% of SCL 100 ns
Data Hold Time
10% of SCL to 10% of SDA (Note 11) 0 0.9 µs
Maximum Receive SCL/SDA Rise
Time
t
R
ns
Minimum Receive SCL/SDA Rise
Time
t
R
(Note 12)
20 +
0.1 x
C
B
ns
Maximum Receive SCL/SDA Fall
Time
t
F
ns
Minimum Receive SCL/SDA Fall
Time
t
F
(Note 12)
20 +
0.1 x
C
B
ns
Transmit SDA Fall Time t
F
(Note 12)
20 +
0.1 x
C
B
250 ns
t
SP
(Note 13) 0 50 ns
SDA Time Low for Reset of Serial
Interface
(Note 14) 150 300 ms
t
HD:DAT
300
300
Pulse Width of Suppressed Spike
t
TIMEOUT
Page 4
MAX7500/MAX7501/MAX7502
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
PIN
MAX7501
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 Over-Temperature 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 +V
S
to set the desired I2C bus
address. Do not leave floating. (See Table 1.)
— 5 RESET
Active-Low Reset Input. Pull RESET low for longer than the minimum reset pulse width
to reset the I
2
C bus and all internal registers to their POR values.
66A1
2-Wire Interface Address Input. Connect A1 to GND or +V
S
to set the desired I2C bus
address. Do not leave floating. (See Table 1.)
77A0
2-Wire Interface Address Input. Connect A0 to GND or +V
S
to set the desired I2C bus
address. Do not leave floating. (See Table 1.)
88+V
S
Positive Supply Voltage Input. Bypass to GND with a 0.1µF bypass capacitor.
Detailed Description
The MAX7500/MAX7501/MAX7502 temperature sensors measure temperature, convert the data into digital
form using a sigma-delta ADC, and communicate the
conversion results through an I
2
C-compatible 2-wire
serial interface. These devices accept standard I2C
commands to read the data, set the over-temperature
alarm (OS) trip thresholds, and configure other characteristics. The MAX7500 features three address select
lines (A0, A1, A2) while the MAX7501 and MAX7502
feature two address select lines (A0, A1) and a RESET
input. The MAX7500/MAX7501/MAX7502 operate from
+3.0V to +5.5V supply voltages of and consume 250µA
of supply current.
MAX7500
MAX7502
Page 5
MAX7500/MAX7501/MAX7502
Digital Temperature Sensors and Thermal
Watchdog with Bus Lockup Protection
_______________________________________________________________________________________ 5
I2C-Compatible Bus Interface
From a software perspective, the MAX7500/MAX7501/
MAX7502 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/MAX7501/MAX7502 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/MAX7502 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
Table 1. I2C Slave Addresses
t
BUF
t
SU:STO
t
HD:STA
t
SU:STA
t
HD:DAT
t
HIGH
t
LOW
t
SU:DAT
t
HD:STA
SCL
SDA
t
F
t
R
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
Page 6
MAX7500/MAX7501/MAX7502
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
(c) T
HIGH
AND T
LOW
WRITE
POINTER
BYTE
POINTER
BYTE
POINTER
BYTE
MOST-SIGNIFICANT
DATA BYTE
LEAST-SIGNIFICANT
DATA BYTE
CONFIGURATION
BYTE
ADDRESS
BYTE
DATA
BYTE
ACK BY
MAX7500/
MAX7501/
MAX7502
ACK BY
MAX7500/
MAX7501/
MAX7502
ACK BY
MAX7500/
MAX7501/
MAX7502
ACK BY
MAX7500/
MAX7501/
MAX7502
ACK BY
MAX7500/
MAX7501/
MAX7502
ACK BY
MAX7500/
MAX7501/
MAX7502
ACK BY
MAX7500/
MAX7501/
MAX7502
START
BY
MASTER
START
BY
MASTER
START
BY
MASTER
REPEAT
START
BY
MASTER
NO
ACK BY
MASTER
STOP
COND BY
MASTER
ACK BY
MAX7500/
MAX7501/
MAX7502
ACK BY
MAX7500/
MAX7501/
MAX7502
STOP
COND BY
MASTER
STOP
COND BY
MASTER
ACK BY
MAX7500/
MAX7501/
MAX7502
Figure 2. I2C-Compatible Timing Diagram (Write)
Page 7
MAX7500/MAX7501/MAX7502
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, T
HIGH
, T
LOW
.
(b) TYPICAL POINTER SET FOLLOWED BY IMMEDIATE READ FOR 2-BYTE REGISTER SUCH AS TEMP, T
HIGH
, T
LOW
.
(c) TYPICAL 1-BYTE READ FROM CONFIGURATION REGISTER WITH PRESET POINTER.
MOST-SIGNIFICANT
DATA BYTE
LEAST-SIGNIFICANT
DATA BYTE
POINTER BYTE
MOST-SIGNIFICANT
DATA BYTE
LEAST-SIGNIFICANT
DATA BYTE
ACK BY
MAX7500/
MAX7501/
MAX7502
ACK BY
MASTER
ACK BY
MAX7500/
MAX7501/
MAX7502
ACK BY
MAX7500/
MAX7501/
MAX7502
ACK BY
MASTER
ACK BY
MAX7500/
MAX7501/
MAX7502
ACK BY
MASTER
START
BY
MASTER
START
BY
MASTER
REPEAT
START
BY
MASTER
START
BY
MASTER
STOP
COND BY
MASTER
STOP
COND BY
MASTER
STOP
COND BY
MASTER
NO ACK BY
MASTER
NO
ACK BY
MASTER
NO
ACK BY
MASTER
Figure 3. I2C-Compatible Timing Diagram (Read)
Page 8
MAX7500/MAX7501/MAX7502
Register Descriptions
The MAX7500/MAX7501/MAX7502 have an internal pnjunction-based 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 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 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 over-temperature shutdown block in comparator
mode. In comparator mode, OS is asserted when the
Digital Temperature Sensors and Thermal
Watchdog with Bus Lockup Protection
8 _______________________________________________________________________________________
REGISTER NAME
ADDRESS (hex)
POR STATE (hex)
POR STATE
(BINARY)
POR STATE (°C)
READ/
WRITE
Temperature 00 ———Read only
Configuration 01 00 0000 0000 — R/W
T
HYST
02 4B0 0100 1011 0 75 R/W
T
OS
03 500 0101 0000 0 80 R/W
Table 2. Register Functions
UPPER BYTE LOWER BYTE
D15
D7
D0
Sign bit
1= Negative
0 = Positive
LSB
xxxxxxx
Table 3. Temperature Register Definition
Table 4. Temperature Data Output
X = Don’t care.
D14 D13 D12 D11 D10 D9 D8
MSB
64°C
32°C16°C8°C4°C2°C1°C
0.5°C
D6 D5 D4 D3 D2 D1
TEMPERATURE (°C)
+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 0110 0xxx xxxx E70x
-55 1100 1000 0xxx xxxx C90x
DIGITAL OUTPUT
BINARY hex
Page 9
temperature rises above the TOSvalue. OS is deasserted when the temperature drops below the T
HYST
value.
See Figure 4. Set bit D1 to 1 to run the over-tempera-
ture 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/
MAX7501/MAX7502 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.
T
OS
and 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/MAX7501/MAX7502 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/MAX7501/MAX7502
Digital Temperature Sensors and Thermal
Watchdog with Bus Lockup Protection
_______________________________________________________________________________________ 9
D7 D6 D5 D4 D3 D2 D1 D0
000
OS polarity
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
T
OS
T
HYST
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
D7
D0
Write
Sign bit
MSB
LSB
x
Read
Sign bit
LSB
0
Table 7. TOSand T
HYST
Register Definitions
X = Don’t care.
Fault queue Fault queue
Comparator/
1 = negative
0 = positive
1 = negative
0 = positive
D14 D13 D12 D11 D10 D9 D8
64°C
MSB
64°C
32°C16°C8°C4°C2°C1°C
32°C16°C8°C4°C2°C1°C
0.5°C
0.5°C
D6 D5 D4 D3 D2 D1
xxxx x x
0000 0 0
Page 10
MAX7500/MAX7501/MAX7502
Shutdown
Set bit D0 in the configuration register to 1 to place the
MAX7500/MAX7501/MAX7502 in shutdown mode and
reduce supply current to 3µA.
Power-Up and Power-Down
The MAX7500/MAX7501/MAX7502 power up to a
known state, as indicated in Table 2. Some of these
settings are summarized below:
• Comparator mode
• T
OS
= +80°C
• T
HYST
= +75°C
• OS active low
• Pointer = 00
Internal Registers
The MAX7500/MAX7501/MAX7502s’ 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/MAX7501/MAX7502 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/MAX7501/
MAX7502 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 MAX7501/MAX7502 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 MAX7501/MAX7502 provides a
way to reset the I
2
C 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 ______________________________________________________________________________________
MAX7500
MAX7501
MAX7502
+V
S
A2/RESET
A1
A0
SDA
SCL
OS
SMBus
INTERFACE
BLOCK
POINTER REGISTER
(SELECTS REGISTER
FOR COMMUNICATION)
DATA
ADDRESS
REGISTER SELECT
GND
TEMPERATURE
(READ ONLY)
POINTER = 0000 0000
T
OS
SET POINT
(READ/WRITE)
POINTER = 0000 0011
T
HYST
SET POINT
(READ/WRITE)
POINTER = 0000 0010
CONFIGURATION
(READ/WRITE)
POINTER = 0000 0001
Figure 5. Block Diagram
Page 11
Applications Information
Digital Noise
The MAX7500/MAX7501/MAX7502 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/MAX7501/MAX7502—specifically
noise with amplitude greater than 400mV
P-P
(the
MAX7500/MAX7501/MAX7502s’ typical hysteresis),
overshoot greater than 300mV above +VS, and undershoot more than 300mV below GND—may prevent suc-
cessful 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 PC board 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/MAX7501/
MAX7502 provide a 6MHz to 12MHz lowpass filter,
which is sufficient filtering in most cases.
Chip Information
TRANSISTOR COUNT: 9611
PROCESS: CMOS
MAX7500/MAX7501/MAX7502
Digital Temperature Sensors and Thermal
Watchdog with Bus Lockup Protection
______________________________________________________________________________________ 11
Page 12
MAX7500/MAX7501/MAX7502
Digital Temperature Sensors and Thermal
Watchdog with Bus Lockup Protection
12 ______________________________________________________________________________________
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages
.)
8LUMAXD.EPS
PACKAGE OUTLINE, 8L uMAX/uSOP
1
1
21-0036
J
REV.DOCUMENT CONTROL NO.APPROVAL
PROPRIETARY INFORMATION
TITLE:
MAX
0.043
0.006
0.014
0.120
0.120
0.198
0.026
0.007
0.037
0.0207 BSC
0.0256 BSC
A2
A1
c
e
b
A
L
FRONT VIEW
SIDE VIEW
E H
0.6–0.1
0.6–0.1
0.50–0.1
1
TOP VIEW
D
8
A2
0.030
BOTTOM VIEW
1
6
S
b
L
H
E
D
e
c
0
0.010
0.116
0.116
0.188
0.016
0.005
8
4X S
INCHES
-
A1
A
MIN
0.002
0.950.75
0.5250 BSC
0.25 0.36
2.95 3.05
2.95 3.05
4.78
0.41
0.65 BSC
5.03
0.66
60
0.13 0.18
MAX
MIN
MILLIMETERS
- 1.10
0.05 0.15
α
α
DIM
Page 13
MAX7500/MAX7501/MAX7502
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
© 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages
.)
SOICN .EPS
PACKAGE OUTLINE, .150" SOIC
1
1
21-0041
B
REV.DOCUMENT CONTROL NO.APPROVAL
PROPRIETARY INFORMATION
TITLE:
TOP VIEW
FRONT VIEW
MAX
0.010
0.069
0.019
0.157
0.010
INCHES
0.150
0.007
E
C
DIM
0.014
0.004
B
A1
MIN
0.053A
0.19
3.80 4.00
0.25
MILLIMETERS
0.10
0.35
1.35
MIN
0.49
0.25
MAX
1.75
0.050
0.016L
0.40 1.27
0.3940.386D
D
MINDIM
D
INCHES
MAX
9.80 10.00
MILLIMETERS
MIN
MAX
16
AC
0.337 0.344 AB8.758.55 14
0.189 0.197 AA5.004.80 8
N MS012
N
SIDE VIEW
H 0.2440.228 5.80 6.20
e 0.050 BSC 1.27 BSC
C
HE
e
B
A1
A
D
0-8
L
1
VARIATIONS:
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