LM89  Product Folder

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 can be accurately determined using the LM89 as long as a dedicated diode (semiconductor junction) is available on the target die. The LM89 remote sensor accuracy of ±1°C is factory trimmed for the series resistance and 1.0021 typical non-ideality factor of the Intel® Pentium™ 4 and the Mobile Pentium™ 4 Processor-M thermal diode. The LM89 has an Offset register to allow measuring other diodes without requiring continuous software management. Contact hardware.monitor.team@nsc.com to obtain the latest data for new processors.

The LM89 and the LM89-1 have the same functions but different SMBus slave addresses. This allows for one of each to be on the bus at the same time.

Activation of the ALERT# output occurs when any temperature goes outside a preprogrammed window set by the HIGH and LOW temperature limit registers or exceeds the T_CRIT temperature limit. Activation of the T_CRIT_A# occurs when any temperature exceeds the T_CRIT programmed limit. The LM89 is pin and register compatible with the LM86, LM90, Analog Devices ADM1032 and Maxim MAX6657/8.

• Accurately senses die temperature of remote ICs or diode junctions
• Offset register allows sensing a variety of thermal diodes accurately
• On-board local temperature sensing
• 10 bit plus sign remote diode temperature data format, 0.125 °C resolution
• T_CRIT_A# output useful for system shutdown
• ALERT# output supports SMBus 2.0 protocol
• SMBus 2.0 compatible interface, supports TIMEOUT
• 8-pin MSOP and SOIC packages

• Processor/Computer System Thermal Management (e.g. Laptop, Desktop, Workstations, Server)
• Electronic Test Equipment
• Office Electronics