Features • Remote diode temperature sensing (2 channels) • 8 positive voltage inputs with scaling resistors for monitoring +5 V, +12 V, +3.3 V, +2.5 V, Vccp power supplies directly • 2 inputs selectable for fan speed or voltage monitoring • 8-bit DAC output for controlling fan speed • Chassis Intrusion Detector input • WATCHDOG comparison of all monitored values • SMBus™ or I2C Serial Bus interface compatibility • VID0-VID4 or IRQ0-IRQ4 monitoring inputs • On chip temperature sensor Description The LM87 is a highly integrated data acquisition system for hardware monitoring of servers, Personal Computers, or virtually any microprocessor-based system. In a PC, the LM87 can be used to monitor power supply voltages, motherboard and processor temperatures, and fan speeds. Actual values for these inputs can be read at any time. Programmable WATCHDOG limits in the LM87 activate a fully programmable and maskable interrupt system with two outputs (INT# and THERM#). The LM87 has an on-chip digital output temperature sensor with 8-bit resolution as well as the capability of monitoring 2 external diode temperatures to 8-bit resolution, an 8 channel analog input ADC with 8-bit resolution and an 8-bit DAC. A channel on the ADC measures the supply voltage applied to the LM87, nominally 3.3 V. Two of the ADC inputs can be redirected to a counter that can measure the speed of up to 2 fans. A slow speed [Sigma][Delta] ADC architecture allows stable measurement of signals in an extremely noisy environment. The DAC, with a 0 to 2.5 V output voltage range, can be used for fan speed control. Additional inputs are provided for Chassis Intrusion detection circuits, and VID monitor inputs. The VID monitor inputs can also be used as IRQ inputs if VID monitoring is not required. The LM87 has a Serial Bus interface that is compatible with SMBus™ and I2C™. Key Specification Voltage Monitoring Error ±2 % (max) External Temperature Error ±4 °C (max) Internal Temperature Error -40 °C to +125 °C ± 3 °C (typ) Supply Voltage Range 2.8 to 3.8 V Supply Current 0.7 mA (typ) ADC and DAC Resolution 8 Bits Temperature Resolution 1.0 °C Applications • System Thermal and Hardware Monitoring for Servers, Workstations and PCs • Networking and Telecom Equipment • Office Electronics • Electronic Test Equipment and Instrumentation

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Datasheet

Title		Size	Date	Other Language
	LM87 Serial Interface System Hardware Monitor with Remote Diode Temperature Sensing	470 Kbytes	10-Dec-03

Featured Application Notes

Title		Size	Date	Other Language
	AN-1260: Application Note 1260 Autonomous Fan Control for Processor Systems Using the LM85	74 Kbytes	10-Mar-04

More Application Notes

Title		Size	Date	Other Language
	AN-1155: Application Note 1155 A Simple Software I2C Routine for the COP8	82 Kbytes	15-May-04
	AN-1260: Application Note 1260 Autonomous Fan Control for Processor Systems Using the LM85	74 Kbytes	10-Mar-04
	AN-1262: Application Note 1262 Four-Speed Fan Control Using Simple Remote Diode Temperature Sensor	70 Kbytes	1-Oct-02

Design Tools

Title	Size	Date
LMxx - Windows 95/98 VXD drivers with stand alone application for talking to temperature sensors or hardware monitors on a mother board	1366 Kbytes	28-Jul-2003

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM87CIMT	CS065	2	38968	52	0	4402000	1	1249079519
LM87CIMTX	CS065	2	38968	52	0	4402000	1	1249079519

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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