LMR12010: Switching regulator is ringing

Sangkyu Kim

Intellectual 290 points

Part Number: LMR12010

Hi, this is my circuit of power.

The switching regulator LMR12010 is ringing. (make sound)

C_in is aluminum electrolytic capacitor.

Another capacitors are chip ceramic capacitor.

Inductor is YCDM4018T-10uH, wire-wound power inductor.

Which component make ringing?

over 8 years ago

0 JohnTucker over 8 years ago

TI__Guru**** 191445 points

I would probably start with adding 10 uF ceramic input capacitor as close to pin 5 as possible. At 10 uF your output capacitor is at the minimum. I would try maybe 3 x 22 uF on the output. Let me know if this fixes your issue or not.

0 Sangkyu Kim over 8 years ago in reply to JohnTucker

Intellectual 290 points

Thanks John

I try add 10uF chip ceramic input cap and

add 2x 22uF tantal cap and 3x22uF.

Each case of 2 or 3 22uF cap reduce rining.

2x 22uF output cap more reduced ringing. But very small rining sound still remain.

0 JohnTucker over 8 years ago in reply to Sangkyu Kim

TI__Guru**** 191445 points

Can you show the SW node waveform?

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LMR12010: Switching regulator is ringing