ADS8685:

Pankaj yadav

Part Number: ADS8685

Dear TI Team,

Do you have ADC which is similar or better in performance to ads8685 but low input ranges. In ads8685, being reference voltage fixed at 4.096V, I cannot go below 2.5V. I want selectable lower Rangle like, +/-0.5V/+/-1.0V onward, upper Side +/-5V or more is acceptable.

Bits - 16 to 20, SAR, Single Channel, Bipolar Input, Sampling Rate > 100 KSPS, Ref - Internal/External, Serial Interferance

Regards

Pankaj Yadav.

over 4 years ago

0 Dale Li over 4 years ago

TI__Mastermind 45715 points

Hi Pankaj,

We do not have this kind of ADC with bipolar direct input and so small input ranges. The closest ADC is ADS125H01 which can support from +/-0.0195V to +/-15.5V single-ended bipolar input signal with internal PGA, 2.5Vref and SPI interface. However, this ADC needs dual high voltage power supplies (+/-18V for supporting +/-15.5V input), also the maximum data rate on this ADC is 40ksps.

There is one solution by using front-end PGA and ADS8685 to meet your requirements and achieve higher sampling rate. See PGA281 OR PGA280(4-ch) for details.

Best regards,

Dale

0 Pankaj yadav over 4 years ago in reply to Dale Li

Prodigy 80 points

Hi Dale,

Thanks for update. I need to use SAR topology only. I can use PGA with ADS8685, but need External Sample and Hold to adjust gain for each sample. I did not find suitable S/H amplifer to suit the rate of 500 KSPS from TI.

Regards

Pankaj.

0 Dale Li over 4 years ago in reply to Pankaj yadav

TI__Mastermind 45715 points

Hi Pankaj,

You need a programmable & variable gain amplifier, not a S/H amplifier. See the PN above.

Best regards,

Dale

0 Pankaj yadav over 4 years ago in reply to Dale Li

Prodigy 80 points

Hi Dale,

Thanks for suggestion.

Regards

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ADS8685: