19-4508; Rev 0; 1/99
Remote/Local Temperature Sensor
with SMBus Serial Interface
The MAX1617A (patents pending) is a precise digital ther-
mometer that reports the temperature of both a remote
sensor and its own package. The remote sensor is a
diode-connected transistor—typically a low-cost, easily
mounted 2N3904 NPN type—that replaces conventional
thermistors or thermocouples. Remote accuracy is ±3°C
for multiple transistor manufacturers, with no calibration
needed. The remote channel can also measure the die
temperature of other ICs, such as microprocessors, that
contain an on-chip, diode-connected transistor.
The 2-wire serial interface accepts standard System
Management Bus (SMBus®) Write Byte, Read Byte, Send
Byte, and Receive Byte commands to program the alarm
thresholds and to read temperature data. The data format
is 7 bits plus sign, with each bit corresponding to 1°C, in
two’s complement format. Measurements can be done
automatically and autonomously, with the conversion rate
programmed by the user or programmed to operate in a
single-shot mode. The adjustable rate allows the user to
control the supply-current drain.
The MAX1617A is nearly identical to the popular MAX1617,
but has improved SMBus timing specifications, improved
bus collision immunity, software manufacturer and device
identification available via the serial interface, and a power-
on reset function that can force a reset of the slave address
via the serial interface.
Desktop and Notebook
Smart Battery Packs
Test and Measurement
SMBus is a registered trademark of Intel Corp.
o Two Channels: Measures Both Remote and Local
o No Calibration Required
o SMBus 2-Wire Serial Interface
o Programmable Under/Overtemperature Alarms
o Supports SMBus Alert Response
o Supports Manufacturer and Device ID Codes
±2°C (+60°C to +100°C, local)
±3°C (-40°C to +125°C, local)
±3°C (+60°C to +100°C, remote)
o 3µA (typ) Standby Supply Current
o 70µA (max) Supply Current in Auto-Convert Mode
o +3V to +5.5V Supply Range
o Small 16-Pin QSOP Package
MAX1617AMEE -55°C to +125°C
*U.S. and foreign patents pending.
Typical Operating Circuit
3V TO 5.5V
ADD0 ADD1 GND
________________________________________________________________ Maxim Integrated Products 1
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