Features • Accurately senses the temperature of remote diodes • Offset register allows use of a variety of thermal diodes • 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 package Description The LM99 is an 11-bit remote diode temperature sensor with a 2-wire System Management Bus (SMBus) serial interface. The LM99 accurately measures: (1) its own temperature and (2) the temperature of a remote diode-connected transistor such as the 2N3904 or a thermal diode commonly found on Graphics Processor Units (GPU), Computer Processor Units (CPU or other ASICs. The LM99 remote diode temperature sensor shifts the temperature from the remote sensor down 16°C and operates on that shifted temperature: The local temperature reading requires no offset. The LM99 has an Offset Register which provides a means for precise matching to various thermal diodes. Contact hardware.monitor@nsc.com for the latest details. The LM99 and LM99-1 have the same functions but different SMBus slave addresses. This allows for one of each to be on the same 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. Key Specification Supply Voltage 3.0 V to 3.6 V Supply Current 0.8 mA (typ) Local Temp Accuracy (includes quantization error) TA = 25°C to 125°C ±3.0°C (max) Remote Diode Temp Accuracy (includes quantization error) TA= 30°C to 50°C, TD= 120°C to 140°C ±1.0°C (max) TA= 0°C to 85°C, TD= 25°C to 140°C ±3.0°C (max) Applications • Graphics Processor Thermal Management • Computer Processor Thermal Management • Electronic Test Equipment • Office Electronics

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Datasheet

Title		Size	Date	Other Language
	LM99 ±1°C Accurate, High Temperature, Remote Diode Temperature Sensor with Two-Wire Interface	349 Kbytes	16-Jul-03

Featured Application Notes

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	AN-1538: Application Note 1538 Interfacing National’s DS90CR218A and LM98714	280 Kbytes	17-Mar-07	中文

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Design Tools

Title	Size	Date
SensorEval Software for Thermal Mangement Products

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM99-1CIMM	CMOS7	0	18406	0	0	1089000	4	309006723
LM99CIMM	CMOS7	0	18406	0	0	1089000	4	309006723

Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR. The Long Term Failure Rates were calculated at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress temperature of 150°C to an application temperature of 55°C.

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