what can cause the Vout of Simple switcher to dip while powering up?

Naji Naufel

Other Parts Discussed in Thread: TPS54231

I have a customer who is using a TPS54231 with Vin=24V and Vout=5V @ 2A feeding a TPS75433 LDO (3.3V out).

The 5V (Blue) starts to rise then dips about 0.5V then rises again. We thought it could be starvation but he disconnected the load from the LDO output (Yellow) and the dip is still there.

Design was done using Webench. No layout guidelines.

I am attaching a scope picture.

What can cause the Buck's output to dip like that?

Thank you,

over 9 years ago

0 Ryan May over 9 years ago

TI__Genius 13700 points

Hello,

Can you post a schematic for your design?

This will help to debug the apparent output instability that you are experiencing during start up. With the schematic to look over we can start to narrow down what could be causing this.