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  • TI Thinks Resolved

ADS8664: Digital output logic level

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Replies: 7

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Part Number: ADS8664

Hello experts,

I have question about Digital output logic level.

In datasheet, Vol max is 0.2 × DVDD when Io = 500-μA sink.

I would like to know Vol max value when Io is different value.

Do you have any data for Vol-Iol curve?

I would like to know resistor value is constant or not when Io is less than 500uA.

Thanks and best regards,

Ryo Akashi

  • Hello Ryo,

    Can you please let me know which Io value you are interested in also if there is a special reason you care it? I do think this 500uA is max current the digital ouput pin can drive also I do not think we have a curve between Vol-Iol, but I would like to check with team after getting your information. Also, are you referring the loading resistor?

    Thanks&regards,

    Dale

  • In reply to Dale Li:

    Hello Dale,

    Thank you for your reply.

    I would like to know whether resistor value between Lower n-channel and ground is constant or not. To know this, Vol-Iol curve is needed.

    If this resistor value is constant, Vol is determined by Iol. So I can expect Vol value roughly.

    I would appreciate if you would give me comment.

    Thanks and best regards,

    Ryo Akashi

  • In reply to Ryo Akashi:

    Hello Ryo,

    Before check with team, I would like to confirm with you about the circuit you showed here, this is not the circuit for this ADS8664 device, right? where (or which device) did you get this circuit? thanks.

    Regards,

    Dale

  • In reply to Dale Li:

    Hello Dale,

    Sorry for my poor explanation.

    This picture is from TI's logic app note.

    The output which we are discussing about is DIGITAL OUTPUTS (CMOS).

    Maybe it's not exact same, but it's same architecture basically. So I pasted that picture.

    Thanks and best regards,

    Ryo Akashi

  • In reply to Ryo Akashi:

    Hello Ryo,

    No problem. I have confirmed with our design team, "Yes, the resistance will be fixed for a given AVDD and IO supply, it can be modeled as a fixed resistance, so you can calculate VOL level for the sink current in your system".

    Thanks.

    Regards,

    Dale

  • In reply to Dale Li:

    Hello Dale,

    Thank you very much for your reply.

    I understand that I can calculate Vol level for the sink current.

    Do you have Vol-Iol curve data?

    If possible could you share me?

    Thanks and best regards,

    Ryo Akashi

  • In reply to Ryo Akashi:

    Hello Ryo,

    As a fixed resistance, the resistance can be modeled and you will be able to calculate VOL for a given sink current. Also, the characterization data can not be shared after confirmed. Thanks for understanding.

    Best regards,

    Dale

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