AM2634: AM263x differential ADC

paulternes

Part Number: AM2634

Page 426 of the AM263x TRM (SPRUJ17C) shows an example ADC code conversion:

On page 428 there are equations that show how to get the ADC code from reference and differential input:

If I plug in 3.2 for (VinPX-VinmX) and 1.8V for (VrefP-VrefM) to match the example from page 426, I get a code of 6336 instead of 4095. Have I misinterpreted the equations? Thanks!

Paul

over 3 years ago

0 Kowshik Gudimetla over 3 years ago

TI__Genius 15435 points

Hi,

I have assigned this thread to the expert and they are out of office due to christmas vacation. Please expect delay on the response.

Thanks

0 Abhijit Das over 2 years ago

TI__Intellectual 870 points

Hello Paul,

Yes the step size definition is incorrect there. The step size is the size of LSB and is defined as the ratio of full scale input voltage and number of ADC output quantization levels. In differential mode the full scale input voltage is -3.2V to +3.2V (6.4V) and ADC o/p will have 4096 codes in that window.

In the above definition you can use step_size = 3.2V*2/4096 or you can use the equation step_size=(VrefP-VrefM)*33/18*2/4224

Thanks

Abhijit

0 paulternes over 2 years ago in reply to Abhijit Das

Prodigy 50 points

Thank you for the clarification!

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AM2634: AM263x differential ADC