TPS5430: TPS5430 output voltage has big noise

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Hello,

Do you have schematic and operating conditions? If it is proprietary you may send it to my email, just click on my name.
Also, what type of noise are you talking about, RF, input / output ripple, or noise below the switching frequency.

Regards, Robert

Dears

Pls check schematic 、layout and output waveform.

Hello,

There are two types of noise in your oscillogram:

Ripple, about 50 mV:
Here are a few things to check when looking at your ripple being too large:
1) Your frequency appears low. It should be 500 kHz but appears to be 167 kHz. This can be caused by current limit or instability.
a. For instability, try removing the 10 uF output capacitor, leaving just the electrolytic
b. Also for instability, the feedback divider (not shown) is likely far from the IC. Since the FB node is high impedance, the divider should be close to the IC so they can share grounds.
c. For current limit, check your load. It should be below 3 A.
2) If the frequency is OK, Check the ESR of the output capacitor.

Switching noise, about 200 mV:

What you are seeing may be due to grounding. Try measuring directly across the output capacitor with your probe configured like on page 6 of the app note whose link is below:

www.ti.com/.../slpa005.pdf

Hello,

Were you able to see the output noise directly accross the output capacitor?