Math question (heat)

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dmpyron
 
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Joined: Mon Dec 10, 2012 11:14 am

Math question (heat)

Post by dmpyron »

Okay, 5V at 500 ma out, right? That means that, assuming perfect conversion, I need to push 2.5 W in at whatever voltage. Say 3.3 V, which means I need .760 ma. Now we both know that perfect is a joke. So, what's the approximate efficiency of the Minty Boost, or does it vary depending on the input? And where should we expect to see the most heat output? Obviously this isn't anything like an Opteron with its 75 W (the reason you want to water cool the sucker) but how much loss is there and, if I had IR goggles would some part light up real big?

Thanks. I think my bed is calling me. Hopefully Cody (my almost three year old Corgi) hasn't claimed my pillow.

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adafruit_support_bill
 
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Re: Math question (heat)

Post by adafruit_support_bill »

80% is a somewhat conservative 'ballpark' figure for estimating purposes. There is a manufacturer's chart about 3/4 down on the design notes page: http://www.ladyada.net/make/mintyboost/process.html
You can see that the efficiency starts to drop with a high load current and a low source voltage. The chip will get quite hot in those conditions.

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