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DAC161P997 application

Jeff Wang100039
Intellectual 2050 points
Other Parts Discussed in Thread: DAC161P997

SCM connect to DAC as DC coupled, send data to DAC161P997 can not have delay otherwise output current will down to 3.4ma.  if want to keep output current to 12ma. how to keep that?

  • 0
    TI__Guru**** 174821 points

    Hi Jeff!

    Is it safe to assume you are using you own hardware here? Are you getting any error messages from the DAC161P997?

  • 0
    TI__Expert 3135 points

    Hi Jeff,

    DAC161P997 , upon power-up, defaults to 3.375mA output. Only new transaction on the single-wire interface can change the current. So the soonest you can update the transmitter output to 12mA is about 1ms after the power-up - that is assuming the 19.2kBaud data rate from the uC. I don't think there is a way around this functionality. But....

    In your application, is the output current always 12mA or above? Or is it expected to go below 12mA.

    If the current is ALWAYS at or above 12mA then you could have a fixed current source installed in parallel with the DAC161P997 - say a resistor between the VD rail of the DAC and the COMA (COMD) node. If that resistor is such that the current through it is 8.627mA, then the additional current sourced by the DAC (3.375mA) will give you the desired output current of 12mA. However, in this example your ability to regulate the output current below 12mA will be limited.

    Jeff, why do you need to start up with 12mA output? Is it possible for you to share with me the application details - maybe then I will be able to help you find the solution.

    If you would like to make this conversation private, please contact me directly at: tom.domanski@ti.com

    Sincerely,

    tom

  • 0 in reply to Tom Domanski24
    TI__Intellectual 2050 points

    I will communicate with customer and then feedback to you.