Measuring operating frequency of a DC-DC converter

[origami]

measure frequency on output of dc dc converter

I am trying to measure the operating frequency of a DC-Dc converter, I do not have access to the internal circuitry of the converter, I can only measure the input and output pins. Is there a way for me to do this? Is the frequency of the ripple the same as the operating frequency of the converter? Thanks!

Please let me know if I am posting in the wrong section of the forum.

 

[sujojk]

measuring a frequency

Just see the output wave form on a scope (with ac input coupling). You can see spikes of amplitude around 100-200mV (may vary) at equal intervals. These spikes are produced when the switch is operated (two spikes - on and off - per cycle) on the dc-dc converter. It gives direct indication towards operating frequency. One more thing to consider is the converter topology. If the converter is of forward topology, spike frequency = operating frequency. Frequency of ripple waveform will be different from operating frequency. (From my personal experience)

Hope this will help.