TPS54427: Overshoot in the wrong end

Niels Vedel

Prodigy 20 points

Part Number: TPS54427

Hi All

I have some noise in this design:

Vin=12V Iout=2A

I measure this signal on the output side of the inductor (L1):

Any ideas what causes the spikes _before_ the level changes?

over 8 years ago

0 Vental Mao over 8 years ago

TI__Expert 5745 points

What's the meaning about this "the output side of the inductor (L1)"? Do this mean the output ripple?
For the output ripple, you need to use the smallest loop of your probe to measure the ripple, such as the tips.
If you still see the spike with the smallest loop probe, you can add a 1ohm resistor in series of the C6, which will decrease the spike and the efficiency.So you need a trade off about this.

0 Niels Vedel over 8 years ago in reply to Vental Mao

Prodigy 20 points

Thank you - You are of cause right - I have to do the measurement right - must be close to weekend.
I will take a look at C6

0 Anthony Lang over 8 years ago in reply to Niels Vedel

TI__Expert 4875 points

Hi Niels,

An RC from SW to GND may also help with the output high frequency ripple and noise spike. Thanks!

Best,
Anthony

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TPS54427: Overshoot in the wrong end