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AN-1171 APPLICATION NOTE Erratum

Question asked by AnalogFran on Jan 31, 2013
Latest reply on Feb 6, 2013 by hmani

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

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