LMZ20502: No Power during Start

Mark Philip Felipe

Part Number: LMZ20502

Hi Team, do you have an experience that during startup the IC only has 0.6V instead of 2.5V. What are the possible usual rootcause of this situation?

Thank you very much.

-Mark

over 3 years ago

0 Chris Glaser over 3 years ago

TI__Guru*** 145650 points

Hi Mark,

I don't quite understand the question. Can you post your schematic and a waveform of Vin, Vout, EN, and PG?

The FB pin is regulated to 0.6V, so it could be that the top FB resistor is shorted. This would give 0.6Vout all the time, and I do not understand what this has to do with startup. Does it ever reach 2.5V?

Would this happen to be the same question as this thread?

0 Mark Philip Felipe over 3 years ago in reply to Chris Glaser

TI__Genius 9705 points

Hi Chris, I sent the schematic in your email.

Thank you.

-Mark

0 Chris Glaser over 3 years ago in reply to Mark Philip Felipe

TI__Guru*** 145650 points

Thank you for sending the schematic Mark. The Cff value is more than 10x the D/S recommended value.

Can you check if this is the same issue as the other E2E thread? If not, we need to see waveforms for your case.

Power management

Power management forum

LMZ20502: No Power during Start