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ADC3662: Power up

Simon Binder
Prodigy 50 points
Part Number: ADC3662

Tool/software:

Hi,

the datasheet says that the REFBUF pin should be have a delay to the AVDD by 2ms:

In the ADC3662EVM schematic is the REFBUF pin connected to AVDD directly via a jumper:

So in my opinion there is no delay included! Is the delay really necessary, or just if you use the internal voltage reference?

  • 0
    TI__Mastermind 28670 points

    Hi Simon,

    I am looking into this for you. Please give me a few days to respond back.

    Thanks,

    Rob

  • +1 in reply to Rob Reeder
    TI__Mastermind 28670 points

    Hi Simon,

    Sorry for the delay and thank you for pointing this out.

    We plan to put this table in the next rev of the datasheet.

    We have not seen any issues on the EVM.

    Regards,

    Rob

    REFBUF voltage

    ADC modes

    Power up Timing

    Comments

    RESET timing

    0 V / grounded

    For Single-ended clk, Internal reference

    No timing required

     

    2ms after VDDA is up

    Floating

    For ext reference, differential clk

    No timing required

     

    2ms after VDDA is up

    1.8 V

    For ext reference, differential clk

    Power up same as VDDA or tie to VDDA

     

    2ms after VDDA is up

    Around 0.6 V

    For int reference, differential clk

    Power up at same time as VDDA

    No issue even if it is set before VDDA or sometime after VDDA

    2ms after VDDA is up

    Exact 1.2V

    Ext ref, Diff clk, Ext BANDGAP

    Power up same as VDDA

    No issue even if it is set before VDDA ; Not safe to power it up after VDDA as it can short ext and int references

    2ms after VDDA is up or after REFBUF pin is up - whichever comes later