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ADS131A04: Can ADS131A04 Support Crest Factor of 3?

Part Number: ADS131A04

Hello,

I'm using the ADS131A04 to measure voltage readings. Currently, we're generating a fundamental (60 Hz) signal with a couple harmonics with high magnitude to produce a crest factor of 3 in the signal. When we do this, we start to see bad readings, with the fundamental magnitude, as well as the harmonic magnitudes, lower than they should be. Other harmonics that weren't part of the signal are also reported. When the crest factor is under 2, all the values look fine.

I've looked over the datasheet, and I see nothing about crest factor, whether there's a maximum or not. I do know that higher frequencies get attenuated, and I've already accounted for that. And we're nowhere near the upper limit of measuring the signal.

I want to rule out where the problem could be, so I'm looking at the A/D converter right now. Can someone confirm that the ADS131A supports a crest factor of 3?

Thanks for your time.

- Tom

  • Hi Thomas,

    Thank you for your post.

    The limitations on the analog input signal are specified in section 7.3 with respect to the analog supplies and the reference voltage. The absolute voltage on either input pin is limited to AVDD and AVSS when the negative charge pump is disabled, and extends to AVDD and AVSS-1.5 V when the negative charge pump is enabled. The differential input voltage (AINxP - AINxN) must never exceed +/- VREF/Gain, otherwise the delta-sigma modulator outputs will saturate to +/- full-scale.

    If you have other amplifiers in the signal path, I would also verify that the input and output swing limitations are not being violated there as well. Forcing a signal too close to the amplifier's supplies may introduce additional non-linear terms in the output signal.

    Regards,