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ADS1235: AVDD - DVDD Power Sequencing

Nicholas Smith1
Prodigy 210 points
Part Number: ADS1235


Can AVDD and DVDD be powered separately from each other to conserve power?

I.e. can I power DVDD and communicate via SPI and the control GPIOs then power via AVDD once I'm ready to convert?

Separate from the above question, we have an existing design with only 2 ADS1235s as the active components where the current jumps to >500mA once reset is driven high through a 10k ohm resistor. We've removed the microcontroller that was connected to the GPIOs, but it seems very strange that these 2 ICs would consume that much current. Any starting points on diagnosing it?

  • +1
    TI__Guru** 113765 points

    Hi Nicholas,

    AVDD and DVDD can be powered independently and can be sequenced in any order.  However, the ADS1235 will be held in a reset state until all supplies are at nominal operating voltage.  So if you power AVDD down and DVDD is still active, the device will be held in a reset state until AVDD is again powered.  So the answer is no, you cannot communicate to the ADS1235 if AVDD power is removed.  Also note that the GPIO although configured through DVDD are actually powered from AVDD.

    As to the issue with excessive current I would have to see a schematic before I can comment.  You can click on my picture icon and start a private conversation with me where you can attach your schematic.

    Best regards,

    Bob B

  • 0 in reply to Bob Benjamin
    Prodigy 210 points

    Looks like there was a short under one of the resistor mods on the board. Primary issue resolved, but looking into other comms issues now.