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DAC60508: Pin configuration when external REF using

Part Number: DAC60508

Dear Specialists,

My customer is considering DAC60508 and has a question.

I would be grateful if you could advise.

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I'd like to use an external REF(3.3V)

(1) When the device powers up, CONFIG Resister bit[8] is 0, this means internal reference is connected and external reference is supplied.

Is there any problem?

(2) When voltage (3.3V) is applied to the REF pin before the device power up, it seems to exceed the absolute maximum rating.(-0.3V ~ Vdd+0.3V)

Is it correct?

If so, does the circuit need to connect the REF pin to an external reference after the device on.

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I appreciate your great help in advance.

Best regards,

Shinichi

  • Inoue-san,

    Shinichi Inoue said:

    (1) When the device powers up, CONFIG Resister bit[8] is 0, this means internal reference is connected and external reference is supplied.

    Is there any problem?

    No - there is no problem. However, it is advised to disable the internal reference as quickly as possible so as to avoid any heating etc. from the conflict of potentials in these two voltages, but there isn't a risk of damage.

    Shinichi Inoue said:
    (2) When voltage (3.3V) is applied to the REF pin before the device power up, it seems to exceed the absolute maximum rating.(-0.3V ~ Vdd+0.3V)

    Unlike the previous case, this would be a risk. The risk would manifest itself in both POR / OTP implications and in damage implications for the I/O cell on the reference input pin. If the current is limited there is less risk for damage, but I would advise compliance to the ROC / Abs Max table.

  • Hi Duke,

    Thank you for your reply.

    As expected, damage could occur when a voltage is applied to the REF pin before  the device on.

    I'll share with the customer they need to supply the REF pin after the device on.

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi