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Hi,
I was measuring the output of the ADC on the given board, but somehow I don' t understand one thing :The input voltage is 1.5V from the power supply. The voltage across the divider i.e. R77 is 0.3073V. When the software is measuring the voltage, it is 0.601 with peak to peak value 2. When I change the value of peak to peak from 2 to 1, then the output of the AC is exactly the same what was the input from the potential divider.
I don't understand why is the software giving the output to be exactly double what is the input?
Thanks
Hi Lavany Pant,
It is not clear what you mean by 'peak to peak', nor is it clear how you have the EVM configured, and whether your external supply source is AC or DC. Is the EVM jumper JP13 connected to AGND or VREF? It might be helpful if you are using the script for Voltage Measurement.
It almost sounds like you are using an AC signal source. Can you attach some pictures of your setup and some screen shots from the GUI to help explain what you are doing and seeing?
Thanks,
Bob B
Hi,
The voltage supply is DC and JP13 was connected to AGND.
When i was supply 1.5V using the voltage measurement script to pin A10, the potential difference across R77 was observed to be 0.30679V. When the script was run and data analysis was done on the delta sigma software, the ADC was measuring the output voltage as double of the voltage across the potential divider i.e. 0.30679*2 with ADC code 4027.
I dont understand why is the ADC output voltage double of the voltage across the dividerR77
Hi Lavany Pant,
Just for clarification are you saying you see 4027 as the code value returned? Or are you saying that you are expecting to see 4027 but are actually getting 2 times the value (8054)? 4027 would be the appropriate code. Computation would be as follows:
Another point of clarification, what do you see in the time domain plot? Here you should see 0.3072V (approximately with noise) when using a 2.5V reference. If the reference voltage is incorrectly set, you may see an incorrect voltage result.
If you are still having issues, can you send me GUI screen shots of the result to illustrate what you are seeing?
Best regards,
Bob B