The LM89 is an 11-bit digital temperature sensor with a 2-wire System
Management Bus (SMBus) serial interface. The LM89 accurately measures its own temperature as well
as the temperature of an external device, such as processor thermal diode or diode-connected
transistor such as the 2N3904. The temperature of any ASIC, GPU, FPGA or MCU can be accurately
determined using the LM89 as long as a dedicated diode (semiconductor junction) is available on the
target die. The LM89 has an Offset register to allow calibration for different nonideality factors
without requiring software management.
Activation of the ALERT occurs when any temperature goes outside a
preprogrammed window set by the HIGH and LOW limit registers or exceeds the T_CRIT limit.
Activation of the T_CRIT_A occurs when any temperature exceeds the T_CRIT
The LM89 is pin and register compatible with the LM86, LM90, LM99, On Semiconductor
ADM1032 and Maxim MAX6657/8.
The LM89C and the LM89-1C have the same functions but different SMBus slave addresses,
allowing multiple LM89's on a bus. LM89-1Ds default local T_CRIT temperature limit is 105°C; all
other versions are 85°C.