SLUA469 Transformer ringing

Kresten Helstrup

Hi Buddies,

I have build a POE board very close to the schematics in the SLUA469. The only thing i changed is R14 to get a 3.5V output instead and R21 to change POE class. Normally the power is working just fine - but sometimes when i start-up the POE the transformer is making a high frequency noise and everything gets pretty hot so i guess the efficiency falls for some reason.

I use approximately 1.5W from the power supply, so maybe this is too little?

Maybe you have a hint with things to check ?

Thanks in advance.

over 11 years ago

0 Darwin Fernandez over 11 years ago

TI__Mastermind 41770 points

Hi Kresten,

This may be a layout issue or assembly issue. You may want to double check connections. The design in the app note is the same as the EVM below. You can try ordering the EVM and comparing waveforms.

http://www.ti.com/tool/tps23750evm-108

Regards,

Darwin

0 Kresten Helstrup over 11 years ago in reply to Darwin Fernandez

Prodigy 50 points

Hey darwin

I can see that the SLUA469 and the EVM-108 uses slightly different components, so i will try to use the ones in the EVM instead, and see if that solves my problems.

Power management

Power management forum

SLUA469 Transformer ringing