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power dissipation design

Robert Hartmann

#4508

power dissipation design | 5 April, 2000

Can someone lead me to some articles or technical standards showing formulas/design criteria for thermal management in a BT BGA? I need to be able to dissipate about 4 Watts, and am having trouble finding information on how to calculate what our BGA will dissipate. Thanks in advance.

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#4509

Re: power dissipation design | 5 April, 2000

Robert: Out of curiosity, by "BT" do you mean: � Bismaleimide triazine, the stuff used to increase the tg of resins used in some BGA interposers. � British Telecommunications plc, the guys with bad teeth. � BrookTree, the RAMDAC supplier, that�s part of Conexant Systems, a Rockwell International spin-off. � BummThing else.

Several points in direct response: 1 There is no standard. 2 Have you considered talking to your device supplier? They often have insights about their products that others over-look. For instance, from stuff we have laying around: � Xilinx: XBRF014 - A Simple Method of Estimating Power in XC4000XL/EX/E FPGAs. A simple method is presented for estimating power dissipation in XC4000X FPGAs. This method is targeted for early estimates during design conceptualization before detailed design information is available. [Folks: I know this is for PGA, not Robert�s BGA; but I�m just using it as an example to support my contention that some device suppliers provide the information Robert seeks.] � Altera: AN74 - Evaluating Power For Altera Devices. This application note discusses how to evaluate and manage power, and provides a simple worksheet for performing power evaluation. [Folks: Now this one is on BGA thermal stuff. See!!!]

Continuing, in AN74, Altera gives guidelines for reducing power dissipation and heat build-up: � Use available low-power features of the device. � Choose a different device package. � Use forced air and/or heat sinking. � Slow the operation in portions of the circuit. � Reduce the number of outputs. � Reduce the amount of circuitry in the device. � Choose a different device family. � Modify the design to reduce power consumption.

3 More broadly, consider: "Hot Air Rises and Heat Sinks: Everything You Know About Cooling Electronics Is Wrong" Kordyban, T ASME Press (0791800741)

My2� Dave F

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