f28335 ADC input noise

hasan mutlu

Other Parts Discussed in Thread: TMS320F28335

i have tms320f28335 experimenter kit. i designed ADC input interface with opamps. Interfcace circuit good working (very low noise) while the output port is not connected to the ADC input of the DSP. But when i connect the output of the interface circuit to the ADC input of the DSP signal noise increases.

What is the problem? What should i do about this problem.

regards.

over 16 years ago

0 superSPACE over 16 years ago

Prodigy 20 points

Maybe the interface needs a LPF filter and sometimes even a cap will decrease the noise significantly; in ti's reference manual, the value of input bypass cap is about 30pF or lower , but as a matter of fact 1nF will be more suitible, of course the value you sample now will be a little lower than the true value.

0 Bulent Ustuntepe over 16 years ago

Prodigy 165 points

Adding LPF is a solution. If you sample AC signals, take care of phase shift.

0 hasan mutlu over 16 years ago in reply to Bulent Ustuntepe

Prodigy 30 points

bulent

yes i sample ac signal. i try 1nF bypass cap. i hope it is solution. but phase shift is problem in my project. because i sample 3-phase currents and voltages respect to real time instantenauosly.

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f28335 ADC input noise