True RMS-to DC converter


Thread Starter


I am working on a project that requires me to convert and AC voltage to a DC voltage. The AC voltage is from a CT that is then rectified to output DC. The DC is then read by a A/D converter (1.75VDC range). I know the rectifier circuit is not very clean and am not sure if a filter is the best answer. I am thinking about a True RMS-to-DC converter, but would like some feedback because the output from the CTs is variable. Can anyone help?

Thanks, Brent

Curt Wuollet

You are going to need active electronics either way. For circuits, google active rectifiers if peak readings adjusted to RMS will be sufficient, that is, if you are dealing with sine waves. Otherwise the TRMS is the way to go, possibly with a stage of amplification to get the signal level compatible with the RMS convertor.

Burr- Brown (now owned by TI), National and Maxim are likely sources for silicon and application notes. I have found NS to have the best application notes and they will send you samples if you do analog designs. This is a big help as some of the chips are hard to find due to volume issues. They have been most helpful, even when I want to do things their chips aren't designed for like using high power audio amps for precision high current pindrivers in ATE.