Specifications

Sensors
Temperature sensing
www.digikey.com/maxim-industrial 71
There is an important advantage to
remote temperature sensors: they
allow you to monitor more than
one hot spot with a single IC. A
basic single remote sensor like the
MAX6642 in Figure 4 can monitor
two temperatures: its own and an
external temperature. The external
location can be on the die of a target
IC, as in Figure 4, or a hot spot on a
board that it monitors with a discrete
transistor. Some remote sensors
monitor as many as seven external
temperatures. Thus, eight locations,
consisting of ICs and board hot
spots, are monitored from a single
chip. Consider the MAX6602 as an
example. This temperature sensor
has four remote diode inputs so
it can monitor the temperatures
of a pair of FPGAs with integrated
thermal diodes, two board hot
spots using discrete transistors,
and the temperature of the board
at the MAX6602’s location. Both
the MAX6602 and the MAX6642
mentioned here achieve ±1°C
accuracy when reading external
thermal diodes.
+3.3V
DXP
SMBCLK
SMBDATA
ALERT
SMBus™/I
2
C SERIAL
INTERFACE
INTERFACE
(TO MASTER)
4.7kΩ
V
CC
GND
CPU, ASIC,
FPGA
ON-CHIP
PN JUNCTION
2200pF
MAX6642
Figure 4. A remote temperature sensor, the MAX6642, monitors the temperature of a sensing transistor (or thermal diode) on
the die of an external IC.
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