ADS8321: Sample Switch Reistance

aarmutat

Intellectual 2590 points

Part Number: ADS8321

What is the sample switch on resistance in ADS8321? Thx.

over 6 years ago

0 ReedKacz over 6 years ago

TI__Intellectual 2540 points

Hello Andy,

I have reached out to the design team for this question. I will post the answer once I hear back.

Thank you,
Reed

0 aarmutat over 6 years ago in reply to ReedKacz

TI__Intellectual 2590 points

Thanks Reed!! Also, could you please confirm – this part’s sample switch only closes after (a) the /CS line goes low and (b) the DCLOCK train is started? So, the sample time window is a fixed # of DCLOCK cycles? (referencing Table I and Figure 6 in the datasheet).

0 ReedKacz over 6 years ago in reply to aarmutat

TI__Intellectual 2540 points

For the ADS8321 specifically, there is a “t_SMPL” that after CS goes low the sampling switch is closed for 4.5 to 5 DCLOCK cycles.

To answer your question directly, the sampling switch only closes for 4.5 to 5 DCLOCK cycles. Your sampling time is a fixed window of DCLOCK cycles.

Also, the design team has begun looking into your R_ON question for the switch.

Thanks,

Reed

0 ReedKacz over 6 years ago in reply to ReedKacz

TI__Intellectual 2540 points

Hello Andy,

I have received an answer from the design team about the switch on resistance for the ADS8321. Ron for both IN+ and IN- is typically 50 ohms. The resistance will change slightly with the input voltage and with temperature. The design team ran a temperature sweep (-40C to 85C) and an input voltage sweep (0V to 5V) -- Ron will be between 32.5 ohms and 73.0 ohms.

If you need a specific resistance based on input voltage and temperature please let me know.

Thank you,

Reed

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ADS8321: Sample Switch Reistance