I am working on an energy metering project using **ADE7763**. I want to have an offset of **+0.4 Wh/h** for the system. CF is disabled. Current sensor is a Shunt of 10mohm. My question is, How to calculate the **APOS** value to compensate +0.4 Wh/h? I have read the datasheet for both calibrating using a reference meter and using an accurate source. Both cases CF is used for the calculation. Could you please help me out? Thank you!

Hi NatsK,

Typically the way we recommend offset calibration to be done is with a two point method. The first point is taken with nominal inputs for which you get a value in the LAENERGY register after you setup line cycle accumulation, lets call this LAENERGYnom. Then you perform the same measurement with the lowest expected current input and take the LAENERGY register value, lets call this LAENERGYmin. The you calculate the error between the LAENERGYexpected (found from LAENERGYnom) and LAENERGYmin and use equation 45 on page 39 of the data sheet to get the APOS value.

The above way would be the most straight forward, now if you know exactly what offset you want (0.4W in APOS) then you have to calculate back from AENERGY to get a "Power" value in LSB's using the CLKIN/4 sample rate, keeping mind the data path:

Then finding what 0.4Wh/h actually translates to in terms of a register value. This way would be more calculation intensive while the first way I mention will require an accurate source or reference meter. Let me know if you need more details.

Best Regards,

David