slide1 l.
Skip this Video
Download Presentation
Thermal Management Solutions Dave Hanrahan Applications Engineer

Loading in 2 Seconds...

play fullscreen
1 / 35

Thermal Management Solutions Dave Hanrahan Applications Engineer - PowerPoint PPT Presentation

  • Uploaded on

Thermal Management Solutions Dave Hanrahan Applications Engineer. Agenda. A look at the Thermal Problem Thermal Diode Monitoring (TDM) Techniques Thermals vs. Acoustics - associated tradeoffs Distributed Temperature Sensing Automatic Fan Speed Control Demo Wrap-up. The Thermal Problem.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
Download Presentation

PowerPoint Slideshow about 'Thermal Management Solutions Dave Hanrahan Applications Engineer' - ikia

Download Now An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Thermal Management Solutions

Dave Hanrahan

Applications Engineer

  • A look at the Thermal Problem
  • Thermal Diode Monitoring (TDM) Techniques
  • Thermals vs. Acoustics - associated tradeoffs
  • Distributed Temperature Sensing
  • Automatic Fan Speed Control
  • Demo
  • Wrap-up

RF Symposium

the thermal problem
The Thermal Problem
  • Equipment required to operate in harsh environments
  • High Reliability: - demand for 24-7 operation
  • System down-time can cost $$$$
  • Need to reduce TCO (Total Cost of Ownership)
  • Trend is towards increased component power and component density on cards/modules
  • Need for predictive failure: - allows equipment to report potential problems before they actually occur

RF Symposium

the thermal problem sources of heat
The Thermal Problem: - sources of heat

Common to have 100W - 200W to be dissipated

RF Symposium

the thermal problem design constraints
The Thermal Problem:- Design Constraints
  • Multiple boards in cabinets restrict airflow: - require many fans to deliver adequate volumetric cooling
  • Low profile systems constrain the amount and physical size of cooling fans limiting CFM delivery
  • Multiple fans will heavily contribute to system noise and current consumption

RF Symposium

thermal diode monitoring tdm
Thermal Diode Monitoring (TDM)
  • A base-emitter PN junction has an inherent temperature dependency which is described by the following equation: - VBE = kT/q * ln (Ic/Is)
  • PN junction voltage changes by -2mV/°C
  • Need to extract this low level signal
  • Remove diode offset
  • Filter Noise

RF Symposium

tdm sampling input stage
TDM Sampling Input Stage

D- is biased a diode drop above GND

I = 12mA, N = 17

Input Low pass filter 65kHz

C1 is optional for noisy environments

Results averaged over 16 conversions

RF Symposium

temperature from v be
Temperature from VBE
  • VBE = kT/q * ln (Ic/Is)
  • VBE1-VBE2 = DVBE =(kT/q) (ln (I/NI)
  • Since I,N, k, q are all known constants then
  • DVBE = (Constant) (T)
  • or T = (Constant) (DVBE)
  • Simple transistor can be used to measure temperature
  • 2-wires can connect to transistor several feet away

RF Symposium

temperature sensing 1 c accuracy
Temperature Sensing: 1C Accuracy






turns on fan


RF Symposium

thermals vs acoustics
Thermals vs. Acoustics
  • Active cooling makes use of fans to push air
  • No. fans required depend on: -
    • system thermal profile
    • physical size of system
  • The greater the no. fans, the better the cooling, but to the detriment of acoustics
  • Automatic Fan Speed Control reduces acoustic noise by optimizing fan speed for measured temperature
  • Reduces system current consumption

RF Symposium

why implement fan speed control
Why implement Fan Speed Control?
  • Reduce Acoustic Noise
  • Reduce Current Consumption
  • Increase Fan Life

RF Symposium

thermals vs acoustics12
Thermals vs. Acoustics
  • Are there Acoustic Noise Standards to be adhered to?
  • ISO 7779: - Noise Emitted by Computer & Business Equipment
  • BLUE ANGEL specs
  • Acoustic Noise Emitted by Telecommunications Equipment
    • (ETS 300 753)

RF Symposium

iso7779 measurement method
ISO7779 Measurement Method




  • Operator Position - 1.2m from floor, 0.25m from equipment
  • Bystander Position - 1.5m from floor, 1m from equipment






RF Symposium

acoustic standards blue angel
Acoustic Standards - Blue Angel
  • Blue Angel specs propose that a PC be no louder than 48dBA in idle state, i.e. with no hard disk or other drive activity.
  • In the active state, i.e. when the hard disk or another drive is being accessed, the machine should be no noisier than 55dBA.

RF Symposium

acoustic standards telecommunications equipment etsi
Acoustic Standards - Telecommunications Equipment (ETSI)

* Measurements taken in accordance with ISO7779

RF Symposium


Any shortcomings/concerns?

  • Specs merely define max “static” noise or noise averaged from equipment over a time period e.g. 24 seconds.
  • However, a fan may be running quieter than noise limit, but may still be cycling up and down, annoying the user.
  • Require some method to account for “dynamic noise behaviour” or rate of change of noise.
  • Filtered Automatic Fan Speed Control Mode is a mechanism with which to defeat this problem.

RF Symposium

distributed temperature sensing
Distributed Temperature Sensing
  • All Temperature Monitoring devices are intelligent, 2-wire bus-based
  • Multiple address selection allows up to 9 devices to be placed on a single bus
  • Multiple remote temperature measurement capability
  • Low cost and extremely small package options

RF Symposium

automatic fan speed control
Automatic Fan Speed Control
  • A single temperature or all temperatures can control the fan speed.
  • Fan Speed varies automatically with temperature.
  • Only 2 parameters required: TMIN & TRANGE

RF Symposium

automatic fan speed control21
Automatic Fan Speed Control


RF Symposium


Effect Of TRANGE Value

13.33% / °C

0.833% / °C

RF Symposium


Filtered Auto Fan Speed Control Mode

  • Allows fan to ramp up or down smoothly to new speed
  • Less acoustic pollution since fan is not cycling up and down with fast temperature transients

RF Symposium


ADM1026 Systems Monitor ASIC

  • Up to 17 Voltage Measurement Channels for PSUs
  • Up to 8 Fan Speed Measurement Inputs
  • Up to 17 GPIOs
  • Remote Temperature Measurement (2 channels)
  • On-chip Temperature Sensor
  • Linear & PWM Fan Speed Control o/p’s
  • 8kB on-chip EEPROM
  • Chassis Intrusion Detection
  • Reset Input, Reset Outputs
  • Automatic Fan Speed Control

RF Symposium

  • Complete systems monitoring solution
  • Monitors system temperatures, voltages and fan speeds
  • EEPROM holds FRU information

RF Symposium

adm1026 software demo
ADM1026 Software Demo

Evaluation software available for all products

RF Symposium


ADM1029 Scaleable, Intelligent Fan Controller

  • Programmable & Automatic Fan Speed Control
  • Dual Fan Speed Measurement
  • Supports Backup & Redundant Fans
  • Supports Hot Swapping of Fans
  • Cascadable Fault Output (CFAULT) for multiple device communication
  • Local & Remote Temperature Monitoring
  • Small 24-pin QSOP package

RF Symposium


ADM1029 Scaleable, Intelligent Fan Controller

  • Fan Free-Wheel Test
  • All Faults, Alarms Are fully Maskable
  • Up to 8 Devices may be addressed in a system using a single address pin (controlling up to 16 Fans)
  • Normal, Alarm & HotPlug speeds are all programmable
  • OFFSET Registers allow offset values to be added to default temperature measurements
  • 15.625Hz, 62.5Hz, 250Hz, & 1kHz PWM drive frequencies available

RF Symposium


ADM1030/ADM1031 Intelligent Temperature Monitor/Fan Controllers

  • Programmable & Automatic Fan Speed Control
  • RPM Mode to maintain constant fan speed
  • Remote Temperature Measurement accurate to 1C
  • 0.125°C Resolution on Remote Temperature channel
  • Local Temp Sensor with 0.25°C Resolution
  • Pulse Width Modulation (PWM) Fan Control
  • Programmable PWM Frequency (10Hz to 100Hz)
  • Tach Fan Speed Measurement for 3-wire fans
  • Analog input measures speed of 2-wire fans

RF Symposium


ADM1030/ADM1031 Features

  • Programmable PWM duty cycle (0% to 100%)
  • Over Temperature (THERM) output
  • Filtered Mode helps dynamic acoustic variations by filtering fans response to temperature transients
  • FAN_FAULT output signals catastrophic fan failure to system

RF Symposium


ADM1030 Application Circuit

N.C. pins represent 2nd temp. & fan channel on ADM1031

RF Symposium

for more information
For more information:
  • email:

RF Symposium