AD7953 conversion of voltage and current in IC and what factors should we apply to measure it correctly

you will need to use Igain and vgain to compensate for gain variation in the signal path. 

244.4mv single ended. I am assuming rms 

220vrms * 1/901 = 244.173mv rms at the adc or 244.173mv * 1.414 = 345pk at the input. 

This is larger than recommended a the adc input at a gain of 1 +/-250mvpk

but for now lets say things are fine. 

on the voltage channel +/-500mv is valid. 

Vrms reg at full scale = 9032007lsb so 353.5mvrms = 9032007lsb of vrms register. 

at 244.173mvrms you should read   9032007 * 244.173/353.5 = 6,238,676d

you should use vgain to adj the rms register to = 6,238,676

Vrms read 6247006d

vrms expected  6,238,676d

vgain reg =   exp/read *0x400000 = 67,019,378 = 0x3FE A272 

write this value to Vgain 0x3FE A272

The rms output should be 6,238,676

so vrms /lsb = 220/ 6,238,676 =3.526389253104345e-5 this would be what you write as a conversion constant in code. 

You should use Igain to adj the rms register to = 6,238,676

same idea just make sure you inputs are within range. 

Dave

same for the vGain

Hi smith, 

Thanks for this detailed clarification.

how you derived vgain reg =   exp/read *0x400000 = 67,019,378 ??

Voltage gain are in order of 1,2,4..16 which are fixed than how to use any derived value for same register. can you explain it.

Thanks

There are 2 gains 

PGA gain which sets the analog gain in the front end. 

XIgain and Xvgain digital gains in the data path to correct for analog gain variation. +/- 3%

www.analog.com/.../ADE7953.pdf

pg 19 for pga gain 

pg 20 and 21 for xIGain and XVGain

pg 34 this section shows how I derived IGain and Vgain:

"how you derived vgain reg =   exp/read *0x400000 = 67,019,378 ??"

I hope this clarifies things

Dave

Yes Dave,

I appreciate your effort to make things clear.

Thanks for your quick response to clarify our doubts. 

Kuldeep 

Hi Dave,

Once again i need your support for ADE7953.

How do I can calibrate & convert raw value of Power and Energy register value to decimal to compare same with other reference data.

Below is the image of some data taken from ADE7953 & Other Ref meter. In last column register count value is shown. 

One more point, I want to calibrate using internal register only, not by CF output. ADE7953 interface with STM32 over SPI. 

As per AN1118, page 11, in establishing the Wh/LSB how to consider accumulation time as continuously data need to use for processing? Or we can use any reference value say 1 sec to compute Wh/LSB value.