TPS54561: negative spike on SW during Vout short test

Given Ding

Expert 8515 points

Part Number: TPS54561

Hi Team，

There is -9V/2ns spike on SW during Vout short test. Please kindly help check if the spike is OK.

BRs

Given

over 3 years ago

0 Marshall_Beck over 3 years ago

TI__Mastermind 30820 points

Hello can you please share waveform and illustrate how the measurement is done on switch node?

The switch node measurement should be done with low inductance return.

0 Given Ding over 3 years ago in reply to Marshall_Beck

TI__Expert 8515 points

Hi,

the waveform is as below.

after checking the measurement setting, the negative spike can be reduced to -7.5V/5ns. Is it OK ? Thanks.

BRs

Given

0 Marshall_Beck over 3 years ago in reply to Given Ding

TI__Mastermind 30820 points

Is this at full load current?

Are you using tip and barrel method for probing switch?

This is wirebound device, I anticipate some ring. This amount of ring seems a little excessive (see fig 38 in D/S), Note, this looks like it was taken at 1A DC load. At 5A, the ring amplitude will be higher.

Also, can you share schematic and layout? I would like to look at input cap placement.

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TPS54561: negative spike on SW during Vout short test