Measureing ripple voltage of DC/DC converter with a DS1052E?

[jb79]

Hello!

I've got a DS1052E with the two original probes and I would like to measure the ripple voltage of a small DC/DC converter with a switching frequency of about 500kHz (as far as I know). Here's the converter: https://www.aliexpress.com/item/10-PCS-Mini-DC-DC-12-24V-to-5V3A-Step-Down-Module-Power-Supply-Module-Converter/32738372200.html

The converter should transfer 15-16V to 3,3V to supply power an ATXMEGA128 and some chips around it, normally about 100mA. For tests I use a 4S Lipo as voltage source that is charged to about 16V.
I allready tried it with the DS1052E but as I found out, it looks like the ripple voltage at these low currents is about 10-15mV or lower, it seems that is really low for the DS1052E. I used AC coupling for CH1 and trigger.
Switching the probe to 1:1 didn't solve the problem, the result looks like crap.

I also have got an old HP3478A multimeter but I think it's frequency range is only 300kHz, so that also won't help me.

Any ideas how I could measure the ripple more precise with my equipment?

[amitchell]

Hi this info from TI should help you out.

https://e2e.ti.com/support/power_management/simple_switcher/w/simple_switcher_wiki/2243.understanding-measuring-and-reducing-output-voltage-ripple

[jb79]

Hi!

Thank you, there are some good hints in this document.