Problem with MCP3905A

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r_senthil_2004

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Hi All,

I'm working on an Energy meter based on MCP3905A.
I used the reference design exactly as per the document DS51565B from Microchip.
I'm using Current Transformer for AC current.
F0, F1 set to 1,
F2, G0, G1 set to 0.
I'm interfacing the Hfout pin with my microcontroller for measurement.
When I connected with Power source and load, the LED D1 (as per the reference design) blinks.

As I understand and as per the datasheet, Each pulse corresponds to a fixed quantity of real energy, selected by the F2, F1 and F0 logic settings. The HFout output has a higher frequency setting and lower integration period such that it can represent the instantaneous active (real) power signal.

But, the problem i see is that the blinking frequency is inversely proportional to the true energy (higher the load, lower the frequency and vice-versa).

As per the datasheet (DS21948D-page 11 - section - A DTF converter accumulates the instantaneous active (real) power information to produce output pulses with a frequency
proportional to the average active (real) power.).

This being a major problem, behavior is contrast to what the datasheet/AppNote states, what could be wrong ? Can you please support me on this ?

This is very urgent for my current project.

Thanks and Regards,
R.Senthil.
 

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