LM94 - TruTherm™ Hardware Monitor with PI Loop Fan Control for Server Management

LM94 - TruTherm™ Hardware Monitor with PI Loop Fan Control for Server Management from the PowerWise® Family

Datasheet	Packaging	Samples & Pricing	Reliability	Knowledge Base

Features

•	8-bit [Sigma][Delta] ADC
•	Monitors 16 power supplies
•	Monitors 4 remote thermal diodes and 2 LM60
•	New TruTherm technology support for precision thermal diode measurements
•	Internal ambient temperature sensing
•	Programmable autonomous fan control based on temperature readings with fan boost support
•	Fan boost support on tachometer limit error event
•	Fan control based on 13-step lookup table or PI Control Loop or combination of both
•	PI fan control loop supports Tcontrol
•	Temperature reading digital filters
•	0.5°C digital temperature sensor resolution
•	0.0625°C filtered temperature resolution for fan control
•	2 PWM fan speed control outputs
•	4 fan tachometer inputs
•	Dual processor thermal throttling (PROCHOT#) monitoring
•	Dual dynamic VID monitoring (6/7 VIDs per processor) supports VRD10.2/11
•	8 general purpose I/Os:
•	4 can be configured as fan tachometer inputs
•	2 can be configured to connect to processor THERMTRIP#
•	2 are standard GPIOs that could be used to monitor IERR# signal
•	2 general purpose inputs that can be used to monitor the 7th VID signal for VRD11
•	Limit register comparisons of all monitored values
•	2-wire serial digital interface, SMBus 2.0 compliant
•	Supports byte/block read and write
•	Selectable slave address (tri-level pin selects 1 of 3 possible addresses)
•	ALERT# output supports interrupt or comparator modes
•	2.5V reference voltage output
•	56-pin TSSOP package
•	XOR-tree test mode

Key Specification

Voltage Measurement Accuracy	±2% FS (max)
Temperature Resolution	9-bits, 0.5°C
Temperature Sensor Accuracy	±2.5 °C (max)
Temperature Range:

LM94 Operational

0°C to +85°C

Remote Temp Accuracy

0°C to +125°C

Power Supply Voltage	+3.0V to +3.6V
Power Supply Current	1.6 mA

General Description

The LM94 hardware monitor has a two wire digital interface compatible with SMBus 2.0. More...

Applications

•	Servers
•	Workstations
•	Multi-processor based equipment

Typical Application

*click for larger image

Parameters Values

Temp Resolution 9-bit/0.5degC

Remote Diode Thermal Sensors 4

TruTherm(TM) Beta Compensation Yes

Analog Inputs 15 to 10, V+

ADC Resolution 8 bits

Fan Speed Inputs 4

Fan Control Output(s) 2 PWM, 22.5kHz

Fan Control Method PI and Lookup Table

VID Inputs Dual 7

Dynamic VID VCCP Monitoring 2

Bidirectional PROCHOT Support 2

GPIOs 8 GPIO, 2GPI, RESET

Interrupt Outputs 1

Reference Voltage 2.5 V

Temperature Accuracy (+/-) 2.5 deg C

Temperature Min 0 deg C

Temperature Max 100 deg C

Interface Type SMBus

Supply Min 3 Volt

Supply Max 3.6 Volt

Quiescent Current 1.6 mA

Resolution 9 bits

Temperature Accuracy (+/-) 2.5 deg C

Automotive Yes

PowerWise Yes

Typical Performance

*click for larger image

Block Diagram

*click for larger image

Datasheet

RoHS Compliance Information	Size in Kbytes	Date
LM94 TruTherm™ Hardware Monitor with PI Loop Fan Control for Server Management	698 Kbytes	24-May-06	Download

If you have trouble printing or viewing PDF file(s), see Printing Problems.

Package Availability, Models, Samples & Pricing

Part Number

Package

Factory Lead Time

Models

Samples &
Electronic
Orders

Budgetary Pricing

Std
Pack
Size

Package
Marking
Format

Type

Pins

Spec.

MSL
Rating

Peak
Reflow

RoHS
Report

CAD
Symbols

Weeks

Qty

$US each

LM94CIMT

TSSOP

NOPB

260

RoHS

Download

Full production

N/A

1K+

$6.20

rail
of
34

NSUZXYTTE#
LM94CIMT

12 weeks

500

LM94CIMTX

TSSOP

NOPB

260

RoHS

Download

Full production

N/A

1K+

$6.20

reel
of
1000

NSUZXYTTE#
LM94CIMT

6 weeks

2000

General Description

The LM94 hardware monitor has a two wire digital interface compatible with SMBus 2.0. Using a [Sigma][Delta] ADC, the LM94 measures the temperature of four remote diode connected transistors as well as its own die and 16 power supply voltages. The LM94 has new TruTherm technology that supports precision thermal diode measurements of processors on sub-micron processes.

To set fan speed, the LM94 has two PWM outputs that are each controlled by up to six temperature zones. The fan-control algorithm can be based on a lookup table, PI (proportional/integral) control loop, or a combination of both. The LM94 includes digital filters that can be invoked to smooth temperature readings for better control of fan speed such that acoustical noise is minimized. The LM94 has four tachometer inputs to measure fan speed. Limit and status registers for all measured values are included.

The LM94 builds upon the functionality of previous motherboard server management ASICs, such as the LM93. It also adds measurement and control support for dynamic Vccp monitoring for VRD10/11 and PROCHOT#. It is designed to monitor a dual processor Xeon class motherboard with a minimum of external components.

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM94CIMT	CMOS7	0	18406	0	0	1089000	4	309006723
LM94CIMTX	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.

For more information on Reliability Metrics, please click here.

[Information as of 7-Nov-2009]