working with 4 pseudo differential signals in mode IV on ADS8363

Alberto Biancalana

Other Parts Discussed in Thread: ADS8363EVM, ADS8363

Hi, I have a simple question about 8363.

In my application I work with 4 analog single ended signals, 0-5V with common mode 2.5V, in mode IV, using ADS8363EVM.

I designed the test system to work in fully differential mode supplying 2.5V stable voltage to all 4 inverting inputs.

This is not a problem but, just to optimize the final application, I wonder if it is possible to simply send the 4 single ended signals to 4 non inverting inputs and use CMA/B as reference for 4 channels only (not 8) in mode IV.

To better explain can I work in pseudo differential mode with CHA1, CHA3, CHB1, CHB3 only and still work in mode IV on the digital side? Can I obtain this using the sequencer?

Or as a simpler alternative, is it safe to supply VREFOUT1 at 2.5V to the 4 non inverting inputs?

Thanks

Alberto

over 13 years ago

0 Tom Hendrick over 13 years ago

TI__Guru**** 181481 points

Hi Alberto,

Special mode IV of the ADS8363 would let you run in Pseudo-differential mode using the sequencer. You would have to set bits [13:12] to 'one' and follow up with bits [11:8] with 01, 11 to select CHA1, CHB1, CHA3, CHB3. You could not sequence A1, A3, B1, B3 though. The control lines get a little trickier in this mode, so you would have to have independent control over both CONVST and RD. It may be simpler for you to leave the ADS8363 in fully diff mode and tie Vref to the (-) inputs, you could then apply your SE input 0-5V signal to the four (+) terminals.

0 Alberto Biancalana over 13 years ago in reply to Tom Hendrick

Intellectual 380 points

Thanks Tom.

I think You are right, the simplest solution is to enable REFIO1 (or 2) at 2.5V and connect to all inverting inputs.

Regards

Alberto

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working with 4 pseudo differential signals in mode IV on ADS8363