PGA Operation

ScEn_283436 · ‎Sep 22, 2015

Hi,

Using a PGA to buffer a small signal before input to a mux and ATD. The part is configured to use Internal Vss.

In the program, I accidently forgot to turn it on via PGA_Start() yet it does give me a directly proportional output with a range that is repeatable and can be calibrated. If the part is turned on, then the dynamic range is reduced to an unusable range, though the ATD count is much higher.

Is the part actually in a low power state and receiving power if I fail to do a PGA_Start()?

ETRO_SSN583 · ‎Sep 23, 2015

I set up attached test bed.

With PGA off, 10 Khz in, G = 1 or 50, I measured 100 mV out of feedthru.

My guess is that when PGA is off the feedthru occurs thru stray C of fdbk network,

which is probably not switched open when PGA is off ? Note I used adjacent pins so

that could contribute to pin to pin coupling. So I moved output to end of port pins

and feedthru dropped to 50 mV.

Regards, Dana.

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PGA Operation

PGA Operation

Re: PGA Operation