Improving output noise on a DPS3003 power supply module

[DG2MMT]

Hi everyone,

I had some really nice success improving the output noise of my DPS3003 based power supply and just want to share my findings.
I recently got my first oscilloscope (!) and one of my first measurements was on the output of my power supply. And what I saw was not so good: ringing noise up to 900 mV peak to peak with a 30 Ω load and 12 V output voltage.
After some testing with different parts I got it down to about 90 mV peak to peak, so I would say, this was a full success.
What did I do?

• Adding a snubber to the switch-node with 2.2 Ω and 620 pF (150 pf || 470 pF)
• adding a filter to the output with a ferrite ring with 2 windings for + and - and a 100 nF capacitor

And here some pictures:
DS1Z_QuickPrint4.png: Output power supply 1 before modification.
DS1Z_QuickPrint25.png: Output power supply 1 after modification.
DS1Z_QuickPrint26.png: Output power supply 2 before modification.
DS1Z_QuickPrint32.png: Output power supply 2 after modification.

[Kleinstein]

Looks impressive for such a small modification.