Hi everyone!

I was very excited about this application note:

**"AN-1171 Calibrating a Single-Phase Energy Meter Based on the ADE7880 by Aileen Ritchie"**

As I was using AN-1076 from the ADE7878 to calibrate the ADE7880, and the process described in the AN-1171 seems much easier.

Its easier because of the gain matching, (generates constants) but... correct me if I'm wrong, there is an erratum in the page 7 of 16.

Where it says: "The following equation describes how to adjust de BIRMS and the CIRMS..."

In those equations, it makes a ratio between AIRMS/BIRMS, AIRMS/CIRMS, AVRMS/BVRMS, AVRMS/CVRMS; and substracts 1. **It supposes tha that ratio minus 1 is always positive**, because in order to make the 24bit hexadecimal representation, he multiplies it by 2^23 (like in page 12 of 12 of AN-1076). The fact I'm pointing is that **it can be negative too. so it would be ((ratio-1)*2^23)+2^24 in that case.**

I would be very grateful if someone replies, as in the last erratum I posted, no one did.

Thanks in advance and best regards,

Francisco Moya

Hi Francisco

Page 7 of AN-1171 shows the equations which give you the decimal equivalent of the register values in integer form( positive and negative). To convert that to hexadecimal, you can take 2's complement for negative numbers.

Regards

hmani