Heating up of LM5085MY IC

Smitha R

Other Parts Discussed in Thread: LM5085

Hi,

we are using LM5085MY IC in our power supply design. (Input 55-64V) and output -41VDC,5A) . while doing temperature rise test, we observed IC heats up to 100 degree centigrade in 15 minutes if we load the output to 1.5A. Attached schematic and layout of IC for reference. Output current requirement is upto 6.5A but even with 1.5A, IC is heating this much so we are not sure about temperature rise at 6.5A output.

Please advise to resolve this heating issue.

Thanks,

smitha R

over 8 years ago

0 Peter Meaney over 8 years ago

TI__Mastermind 31580 points

Hi,

This post belongs in the non-isolated dc/dc forum I will move the post to the correct forum and I have asked one of the applications engineers to respond to the post.

Regards

Peter

0 Vijay86929 over 8 years ago

TI__Genius 11490 points

Hi Smitha,

What is the switching frequency of the design? It seems R39 is 1.33k which should result in very high frequency. I recommend using the LM5085 quickstart calculator here: http://www.ti.com/product/LM5085/toolssoftware

Thanks adn regards,
Vijay

0 Smitha R over 8 years ago in reply to Vijay86929

Intellectual 790 points

Hi Vijay,

There is a mistake in that value given in Schematic, we are testing by placing resistor of 1.47M ohm in place of R39 (180KHz of switching frequency) . Design has been done by using the quick start calculator which you have mentioned. But still we are facing that heating issue.

Request you to advise as soon as possible.

Thanks,

Smitha R

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Heating up of LM5085MY IC