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ADS7841-Q1: Recommended circuit and some questions

na na78
Guru 16770 points
Part Number: ADS7841-Q1
Other Parts Discussed in Thread: ADS7841,

Hi

We want to increase precision of AD conversion.

1.
Now we are referring Figure 1.
Is this the best configuration?
For example, would it be better that suppling Vcc and reference voltage sepalately?
Do you have recommended schematic or layout guideline?

2.
I want to confirm reference and COM.

Assumed single-end input,
if reference and VCC are 5V and COM is ground, analog input range would be 0V to 5V.
If reference is 3V, VCC is 5V and COM is 0.5V, analog input range is 0.5V to 3.5V.

Is my understanding correct?

BestRegards

  • 0
    TI__Expert 5575 points

    Hello Na na 78

    1. It is better to driveVCC and VREF pin seperately. Select low drift, low output impedance reference to drive VREF pin.

    2. Your understanding about input range in single ended configuration is correct

    Can you please let me now what is the end application for this device

    Thanks & Regards

    Abhijeet

  • 0 in reply to Abhijeet Godbole
    Guru 16770 points
    Hi Adhijeet

    Thank you for your reply.

    >1. It is better to driveVCC and VREF pin seperately. Select low drift, low output impedance reference to drive VREF pin.

    Is there any reference materials? (It would be OK if it uses other ADC device)

    The application is automotive sub battery.
    I can't say in detail.

    BestRegards
  • 0 in reply to na na78
    TI__Expert 5575 points

    Na na 78

    Here is the link for reference buffer driver circuit. This paper talks about composite buffer architecture which is required for higher precision ADCs (16 bit and above)

    For ADS7841 (12 bit resolution), driving reference pin through good enough voltage references such as REF5025-Q1 should be fine.

    Thanks & Regards

    Abhijeet

  • 0 in reply to Abhijeet Godbole
    Guru 16770 points
    Hi Adhijeet

    I'm sorry additional comment to resolved thread.

    I could not see link you had introduced for me.

    >Here is the link for reference buffer driver circuit.
    >This paper talks about composite buffer architecture which is required for higher precision ADCs (16 bit and above)

    Could you please show me the link again?

    BestRegards
  • 0 in reply to na na78
    TI__Expert 5575 points
    Na na 78

    You can search for document tidu012c on ti.com. Link to the TIPD is "www.ti.com/lit/ug/tidu012c/tidu012c.pdf"

    The theory of operation and compoent selection section talks about reference driver circuit needed for >16 bit ADCs.

    For ADS7841-Q1 REF50xx-q1 should be good enough to drive REF pin

    Thanks & Regards
    Abhijeet