Features Temperature sensing 6 positive voltage inputs with scaling resistors to monitor +5V, +12V, +3.3V, +2.5V, Vccp power supplies directly 8-bit DAC output for controlling fan speed 2 fan speed monitoring inputs Chassis Intrusion detector input WATCHDOG comparison of all monitored values SMBus™ 1.0 (LM81C) and 1.1 (LM81B) Serial Bus interface compatibility LM81B has improved voltage monitoring accuracy VID0-VID4 monitoring inputs Description The LM81 is a highly integrated data acquisition system for hardware monitoring of servers, Personal Computers, or virtually any microprocessor-based system. In a PC, the LM81 can be used to monitor power supply voltages, temperatures, and fan speeds. Actual values for these inputs can be read at any time. Programmable WATCHDOG limits in the LM81 activate a fully programmable and maskable interrupt system with two outputs (INT# and T_CRIT_#). The LM81 has an on-chip digital output temperature sensor with 9-bit or 12-bit resolution, a 6 analog input ADC with 8-bit resolution and an 8-bit DAC. Two fan tachometer outputs can be measured with the LM81's FAN1 and FAN2 inputs. The DAC, with a 0 to 1.25V output voltage range, can be used for fan speed control. Additional inputs are provided for Chassis Intrusion detection circuits, and VID monitor inputs. The LM81 has a Serial Bus interface that is compatible with SMBus™. Key Specification Voltage Monitoring Error +2% or ±1.2% (max) Temperature Error -40°C to +125°C ± 3°C (max) Supply Voltage Range 2.8V to 3.8V Supply Current 0.4 mA (typ) ADC and DAC Resolution 8 Bits Temperature Resolution 0.5°C Applications System Thermal and Hardware Monitoring for Servers and PCs Office Electronics Electronic Test Equipment and Instrumentation

Datasheets

Title		Size	Date	Other Language
	LM81 Serial Interface ACPI-Compatible Microprocessor System Hardware Monitor	417 Kbytes	22-Feb-02	日本語

Application Notes

Title		Size	Date	Other Language
	AN-2113: Application Note 2113 Applying I2C Compatible Temperature Sensors in Systems with Slow Clock Edges	81 Kbytes	3-May-11

Other Technical Documents

Title		Type	Date
	Sensing and Monitoring for Control and Protection Seminar	App Note	2003-02-17
	Cost Effective Partitioning of IO and Management Functions in PCs - Introduction of SensorPath™ Technology	Technology Edge	2004-01-01

Part Number(s) (NSID)	Top View	Availability	Current Reported Stock	Budgetary Pricing	Pack Size
LM81BIMT-3/NOPB LM81BIMT-3 RoHS Status	TSSOP	Full production Lead Time: 6 weeks	Distributor Region Qty ARROW Worldwide 1196 DIGI-KEY Worldwide 538 MOUSER Worldwide 219 NEWARK Americas 60 TAYLOR Americas 1196	$1.70 each at 1K+ pcs	rail of 61
LM81BIMTX-3/NOPB LM81BIMTX-3 RoHS Status	TSSOP	Full production Lead Time: 6 weeks	Distributor Region Qty CEAC Asia Pacific 17500 DIGI-KEY Worldwide 0	$1.70 each at 1K+ pcs	reel of 2500
LM81CIMT-3/NOPB LM81CIMT-3 RoHS Status	TSSOP	Full production Lead Time: 6 weeks	Distributor Region Qty ARROW Worldwide 1124 DIGI-KEY Worldwide 234 FARNELL Europe and Asia 243 MOUSER Worldwide 169 NEWARK Americas 243 TAYLOR Americas 1124	$1.70 each at 1K+ pcs	rail of 61
LM81CIMTX-3/NOPB LM81CIMTX-3 RoHS Status	TSSOP	Full production Lead Time: 6 weeks	Distributor Region Qty ARROW Worldwide 5000 AVNET-EM Worldwide 5000 DIGI-KEY Worldwide 0 TAYLOR Americas 5000	$1.70 each at 1K+ pcs	reel of 2500

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM81.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM81 is located at RoHS Status.

Part Number(s) (NSID)	Weight (milligrams)	Type	Pins	MSL Rating	Peak Reflow	RoHS Status	CAD Symbols	Models	Package Marking Format
LM81BIMT-3/NOPB LM81BIMT-3	83.622 84.002	TSSOP	24	1 1	260 260	Detail	Download	N/A	NSUZXYTTE# LM81 BIMT-3
LM81BIMTX-3/NOPB LM81BIMTX-3	83.622 84.002	TSSOP	24	1 1	260 260	Detail	Download	N/A	NSUZXYTTE# LM81 BIMT-3
LM81CIMT-3/NOPB LM81CIMT-3	83.622 84.002	TSSOP	24	1 1	260 260	Detail	Download	N/A	NSUZXYTTE# LM81 CIMT-3
LM81CIMTX-3/NOPB LM81CIMTX-3	83.622 84.002	TSSOP	24	1 1	260 260	Detail	Download	N/A	NSUZXYTTE# LM81 CIMT-3

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM81.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM81 is located at RoHS Status.

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

CAD Symbols and Models Download LM81 CAD Symbols

Models N/A

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM81BIMT-3	CS065	2	47473	43	0	5527000	1	1568301341
LM81BIMTX-3	CS065	2	47473	43	0	5527000	1	1568301341
LM81CIMT-3	CS065	2	47473	43	0	5527000	1	1568301341
LM81CIMTX-3	CS065	2	47473	43	0	5527000	1	1568301341

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.

For more information on Reliability Metrics, please click here.

All information pertaining to the RoHS Compliance Standard can be found at http://www.national.com/en/packaging/leadfree.html.

Moisture Sensitivity Level Data for LM81.

A RoHS compliance or an IPC 1752 report can be acquired at http://www.national.com/en/packaging/greennopb.html.

National's certificate of product compliance for LM81 is located at RoHS Status.