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DAC60508: Confusing VREF

MARK KERESTES
Prodigy 80 points
Part Number: DAC60508

I'd like to drive the DAC60508 outputs to the VCC rail of 3.3V+/-5%.

Can I connect VREF to VCC with DIV=2 and GAIN=2 without getting a reference alarm condition that shuts down the DAC outputs.

I see you have divided the Vrefin spec in recommended operating conditions table to two cases. One for VDD=2.7 to 3.3V and a second for Vdd=3.3 to 5.5V.

  • 0
    TI__Genius 14220 points

    Hi Mark,

    Welcome to E2E and thank you for your query.

    You're right. However, we don't recommend shorting VDD and VREF as the PSRR will be degraded drastically. In case, you want to go ahead anyway, the following explanation might help.

    For a VDD between 2.7V to 3.3V, the maximum reference is (VDD-0.2). That means if you use a 3.3V reference input and select reference divider as 2 and gain as 2, the maximum output will be VDD - 0.2V.

    By default, the reference divider is set to a dividing factor of 1. Hence, you need to set it to 2 in order to get the output.

    Use sufficient filtering between VDD and VREF so that VREF is not impacted by the switching transients from VDD.

    Hope that answers your question.

    Regards,

    Uttam Sahu

    Applications Engineer, Precision DAC