LM5025AEVAL: Vout issue

Ting YI

Part Number: LM5025AEVAL

The input voltage for the LM5025AEVAL is 36V to 72V, but why is it that the one I built can only output normally from 36V to 39V.

Also, when it outputs normally, the waveform of OutA is abnormal. I have already increased the filter resistor and capacitor values for CS1, but it seems to have made no improvement.

over 1 year ago

0 Hong Huang over 1 year ago

TI__Guru 73265 points

Hi,

I think you need to first list the difference between your design and the EVM.

Then decide why you did the difference and decide if ok to eliminate the difference.

Alternatively you can compare the waveforms to see where the differences are then try to resolve.

0 Ting YI over 1 year ago in reply to Hong Huang

Prodigy 140 points

Hi,

However, I have not modified the EVM circuit; it was built entirely according to the provided specifications.

0 Hong Huang over 1 year ago in reply to Ting YI

TI__Guru 73265 points

Hi,

If your board is a copy and paste of the EVM, you need to compare your board to the EVM to check where you did something wrong. One possible way is to swap components between the EVM and your board, starting with the transformer, MOSFETs, etc.

The EVM works just fine but your board cannot - it means you did something wrong, including some components maybe wrong, PCB problems, solder issues. This requires you make check a bit by bit to find out. There is really no shortcut to resolve this.

You can start to check your board first to make sure your bare board is good first.