Remote and Local Temperature Sensor with SMBus, I2C Interface

The LM82 is a digital temperature sensor with a 2 wire serial interface that senses the voltage and thus the temperature of a remote diode using a Delta-Sigma analog-to-digital converter with a digital over-temperature detector. The LM82 accurately senses its own temperature as well as the temperature of external devices, such as Pentium II Processors or diode connected 2N3904s. The temperature of any ASIC can be detected using the LM82 as long as a dedicated diode (semiconductor junction) is available on the die. Using the SMBus interface a host can access the LM82's registers at any time. Activation of a TCRITA output occurs when any temperature is greater than a programmable comparator limit, TCRIT. Activation of an INT output occurs when any temperature is greater than its corresponding programmable comparator HIGH limit.

The host can program as well as read back the state of the TCRIT register and the 2 THIGH registers. Three state logic inputs allow two pins (ADD0, ADD1) to select up to 9 SMBus address locations for the LM82. The sensor powers up with default thresholds of 127°C for TCRIT and all THIGHs. The LM82 is pin for pin and register compatible with the LM84, Maxim MAX1617 and Analog Devices ADM1021.