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


ParametersValues
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 KbytesDate Click link below to Download
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 NumberPackageFactory Lead TimeModelsSamples &
Electronic
Orders
Budgetary PricingStd
Pack
Size
Package
Marking
Format
TypePinsSpec.MSL
Rating
Peak
Reflow
RoHS
Report
CAD
Symbols
WeeksQtyQty$US each
LM94CIMTTSSOP56NOPB2260RoHS Download Full productionN/A
Samples
Buy Now
1K+$6.20rail
of
34
NSUZXYTTE#
LM94CIMT
12 weeks500
LM94CIMTXTSSOP56NOPB2260RoHS Download Full productionN/A
 
Buy Now
1K+$6.20reel
of
1000
NSUZXYTTE#
LM94CIMT
6 weeks2000

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)
LM94CIMTCMOS70184060010890004309006723
LM94CIMTXCMOS70184060010890004309006723

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]