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Any IC for measuring RMS voltage?
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Manx:
I need to measure RMS voltage of pulsed DC, in the range up to ~100 mV, with at least 16 bit resolution, from two channels, and output it via I2C (preferably) or SPI. Supply is 3.3 V. I don't want to calculate the RMS voltage myself and I'd like to use some ready-made integrated solution.

Unfortunately, I cannot find any IC that could do this. I only found some RMS-to-DC converters, that I could put before the existing slow ADC interfacing with slow and small microcontroller. These converters are however very expensive compared to the cost of other components (and I'd need two of them). Also, at least the ones I found, need dual supply.

Do you know of any IC that may be of use to me?
dzseki:
For a pulsed DC signal (that is a square wave in nature) the RMS is the same as the average, and you can obtain the average by a simple low pass filtering, no?
coromonadalix:
You have the famous ad636 or ad637 used in multimeters ?
Manx:
By "pulsed" I mean rectified AC. Or worse.

@coromonadalix , AD636 was what I had in mind when I was thinking about RMS-to-DC converters. The problem is, when used with a single supply, it requires 5 V. I have only 3.3 V.

BTW, are they really famous and used in multimeters? Like, are they THE chips for the job?
Wytnucls:
AD 736/737
Wide power supply range: ±2.5 V to ±16.5 V
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