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ADC3662: Hardware Reset

Simon Binder
Prodigy 50 points
Part Number: ADC3662

Tool/software:

Hi,

is there always a hardware reset needed after power-up phase?

If yes, would it also be possible to keep the RESET pin at high from beginning, so:

Thanks for help!

  • 0
    TI__Mastermind 23750 points

    Hi Simon,

    A hardware reset is advised such that the registers reset to a known state each and every time the device is powered on. It is an active high signal that should be toggled only after the supplies have all settled. If you leave it high while the supplies are turning on, we cannot guarantee the register state across power cycles.

    The normal practice is to use a watchdog circuit based on the last power rail to come up, in this case, AVDD18. The diagram shows to assert reset after REFBUF is stable, but since the REFBUF can be used for bootstrap selection, it's better to place the watchdog on the AVDD rail and the watchdog delay will account for the time that REFBUF settles. This circuit below will work for the active high reset this part requires.

    Thanks, Chase

  • 0 in reply to Chase W
    Prodigy 50 points

    Hi Chase,

    we didn't connect the HW reset in the first design and the ADC still works. Which drawbacks should we expect due to the missing HW reset?

  • +1 in reply to Simon Binder
    TI__Mastermind 23750 points

    Hi Simon,

    The hardware reset is so the registers reset to a known state each and every time the device is powered on. If you trigger software reset this will also accomplish the same, however many customers require a known device state immediately at power up, which is why our devices have a hardware reset.

    Thanks, Chase