Quote Originally Posted by Divya View Post
1) When internally CS5460A registers stores measurement results in 24 bit words if we remove the last 8 bits and consider only the first 16 bits how the results come alright. Can anybody kindly explain to me with a sample value.
Look carefully at the following sections:
- App Note-page 5 - RMS Voltage
- CS5460A Data Sheet-page 13 - 2.2 Performing Measurements
- CS5460A Data Sheet-page 47 - 5.6 and 5.7 (Output register results)

What they are saying in a nutshell is that the output registers indicate the percentage of the maximum input values. So the output (for Irms for example) would be a number between in the range 0<= N<1. Because some can be negitive, they will be in the range -1<=N<1. These are given in two's complement notation, with the MSB the sign bit for the signed values. Table 1 on page 14 may help.

As a two's complement notation to 24 bits (23 for the signed numbers), the least significant bits represent such a small percentage that they are insignificant. For example:

11111111 11111111 11111111 = 0.99999994
11111111 11111111 00000000 = 0.999984741
00000000 00000000 11111111 = 0.000015199

As you can see, the last 8 bits can easy be dropped unless the unmost of percision is required.


Quote Originally Posted by Divya View Post
2) Secondly how the values declared in the MAXPWRH & MAXPWRL registers are arrived at. ie., 0x98CE and 0xB3f1
Not sure, that would take a little more looking into.

SteveB