Ripple voltage measurement

[narendra]

Hi,

Can you please help in selecting the DMM card, which will measure the SMPS  output AC ripple in DC voltage?

The Ripple voltage frequency is 50KHZ.

I have seen NI 4050 and NI 4060 of NI DMM’s, but it looks it will measure upto25KHZ.

I don’t want to use oscilloscope for this, as I’m in border level of my system target cost.

Your help in this regard is greatly appreciated.

Regards,

Narendra

 

[AllanS]

Hello narendra!

The 407X series of DSA boards can measure up to 300KHz.  The link below will take you to the specs. of this series of DMMs.  Notice page 4.

http://www.ni.com/pdf/manuals/371304d.pdf

Have a great day!

Allan S.

National Instruments

[narendra]

Thanks Allan S.

Narendra sabbineni

[Buechsenschuetz]

When measuring AC voltages with odd waveforms (as the ripple voltage in your application probably is) make sure the acquisition system performs a true RMS measurement.

If you want to measure peak ripple voltages I think you will have to turn to a fast oscilloscope since sometimes the peak spikes are very fast.

[sead_suskic]

Very good point about the ripple measurement and the need for relatively fast digitizer. If you use one of NI 407x DMMs, you might not need an additional digitizer because in addition to being full featured DMMs, NI 407x DMMs can operate in thr isolated digitizer mode allowing you to capture waveforms at rates up to 1.8 MSamples/s - we refer to this as the waveform mode in NI-DMM driver.