MC34063 Step-down Converter Heating Problem

Anand P. Paralkar · 2011-07-26T17:42:59+00:00

Hi,I have constructed a DC-DC step-down converter using the MC34063. The circuit I use is very similar to the one shown here:My circuit does not have the Zener, output side LED and input side protection diodes (TVS1 and D2 in the circuit). The rest of the circuit is quite similar.The operating conditions for my circuit are as follows:Vin : 10V to 30V.Vout : 5VIout: 250mAI tested the circuit at:Vin: 10V, Vout: 5.3V, Iout: 250mAI observe that the MC34063 is heating. I am unable to say whether this heating is acceptable.You could help me by answering these questions: 1. Is there an accurate/thumb-rule method of _measuring_ the amount of power dissipated in an IC (MC34063 in this case). 2. Categorically confirm or deny that the MC34063 is likely to heat at the test conditions (Vin: 10V, Vout: 5.3V, Iout: 250mA). 3. Methods to reduce the power dissipation in the MC34063 at these test conditions. 4. Is the heating really a problem?I realise that some of these questions are open-ended, but it would be great to get some tips from the experts. Thanks a lot for your time.Thanks,Anand

Jul 26, 2011 21 Replies

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Michael A. Terrell 14 years ago

stool

Again

the boss

Sounds like you aimed WAY too low. :)

It's easy to think outside the box, when you have a cutting torch.

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Joerg 14 years ago

I designed a board for fast switching of optical switches. The only available supply was a 12V rail so I made the needed HV. Had large font warnings on there in English and Spanish. "Peligro" and all that. Guess who was the guy the board bit?

A Chinese engineer was laughing, said he didn't get bitten even though he was not the designer and the warning was not on there in Chinese.

Regards, Joerg http://www.analogconsultants.com/

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