accurate volt measurement over isolation barrier - analog please

[Easy peasy]

Hello all, need to measure 0 - 760VDC over an isolation boundary of 3500Vac, ideally to 1V accuracy or so,

ideally an opto circuit that doesn't drift too much ( unlikely I know given opto's )

or something else

if you know of something that works - please post

kind regards

 

[FvM]

State-of-the-art isolation amplifiers, e.g. from TI are using duty cycle or SD ADC, digital isolator and single bit DA. ISO121 is even supporting 3500 V working voltage. Is there a specific reason not to use a similar approach?

 

[Warpspeed]

I have had success with voltage to frequency conversion, a single opto, then frequency measurement over a long enough period to average out any FM noise.

 

[Easy peasy]

thanks for the above comments, we are looking at the IL300-E or -F as it seems to be stable over time and temp

A first design gets better than 0.25%, which is 1.9 volts on 760 - down side is that it needs a small low temp Co. trim pot to set it exactly ...

5300Vac for 1 sec