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ADS7805: Power up / down sequence for VDIG amd VANA

Takahiro Saito
Expert 5315 points
Part Number: ADS7805

Hi team,

My customer asked about the power up/down sequence for VDIG and VANA.

Based on the datasheet, it seems that customer need to keep the voltage difference VANA and VDIG within 0.3V and keep VANA > VDIG even when powering up/down. Is this the recommend power up down sequence?

If either VDIG or VANA happens to be disconnected, is there any risk of damage to the IC?

Regards,

Saito

  • 0
    TI__Mastermind 35520 points

    Hi Saito,

    This ADC requires to keep VDIG ≤ VANA, a simple way to do this for optimum performance is to tie both VDIG and VANA to the same +5V power supply source. Regarding the Absolute Maximum Rating in the ADC datasheet, the VDIG should not beyond VANA+0.3V.

    Regarding your specific question,

    If the VDIG is disconnected and the VANA is still on, there is no violation to the datasheet and no any issue.

    If the VANA is disconnected and the VDIG is still on, that will violate the datasheet and will be a risk to damage the device.

    I hope this helps.

    Regards,

    Dale