ADS8412: Combination of ADS8412 and THS4131

MESH

Part Number: ADS8412
Other Parts Discussed in Thread: THS4131, ADS8422,

Hello,

I considering AD conversion circuit that circuit is used ADS8422 and THS4131.
Current my schematic is besed on circuit of figure 29 of ADS8422 data sheet.
However, current market inventry of ADS8422 has become zero.

Therfore, I am thinking of replacing ADS8422 with ADS8412.
Since the ADS8412 has no COMMOUT signal, I will add a 2.048V reference voltage IC for input to the VOCM pin of the THS4131.

The input voltage range of THS4131 is +/-10V.
The gain of THS4131 is 0.325. (conbination of 390ohm and 1200ohm)

I would like to know the comments on the combination of ADS8412 and THS4131.

Regards,
MESH

over 2 years ago

+1 Keith Nicholas over 2 years ago

TI__Mastermind 41230 points

Hello MESH,

The analog input structure of ADS8412 is very similar to ADS8422. The two key parameters are the input sampling capacitance and the acquisition time.

ADS8412:
Input capacitance, 25pF
Acquisition time, 100nsec

ADS8422:
Input capacitance, 30pF
Acquisition time, 70nsec

Because the ADS8412 has less sampling capacitance and more acquisition time to settle, it will be easier to drive. The THS4131 will be able to drive this input with no issue in this case since it can drive the higher capacitance of the ADS8422 in a shorter time (70nsec).

If interested in more details on how to drive switched capacitor ADC inputs, take a look at the TI Precision Labs - ADCs material.

https://training.ti.com/introduction-analog-digital-converters-adcs?context=1128375-1139102

Regards,
Keith Nicholas
Precision ADC Applications

0 MESH over 2 years ago in reply to Keith Nicholas

Intellectual 860 points

Hello Keith,

Thank you for your reply.

Your reply is very helpful for me.

Regards,

MESH

+1 Keith Nicholas over 2 years ago in reply to MESH

TI__Mastermind 41230 points

You are welcome!

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ADS8412: Combination of ADS8412 and THS4131