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AMC7891 Power up sequence ambiguity in data sheet

Other Parts Discussed in Thread: AMC7891

The power up sequence for the AMC7891 states: "Supply all voltages (AVDD, GPIOVDD and SPIVDD). If possible, it is recommended to apply IOVDD before AVDD. However, the supplies can be powered up simultaneously or in any order with no detrimental effect to the device."

Our current power up sequence has AVdd coming up before GPIOVdd and SPIVdd which according to the directions, is not recommended, but will have no detrimental effect. Why is it not recommended and is there anything I need to watch out for?




  • Howdy Dan,

    Welcome to the e2e forums!  As you've read the part has no particular power sequence.  The only thing to verify when powering the device is that the GPIO inputs are applied after AVDD is fully ramped.  If the inputs are brought up before AVDD then the device may not work properly.  Additionally, if using an external ADC reference, AVDD must power up before the external reference voltage is applied to the REF pin.

    Many other designs include ESD diodes between supplies, which prevent random sequencing. Usually, this information can be derived from the absolute maximum ratings table, which sometimes displays the max or min in relation to a voltage or supply.  There are no ESD diodes limiting the supplies to other supplies in this device, therefore this device allows the user to sequence the device with any power sequence.

    Best Regards,


  • Thanks for the quick response Matt. We are not using the GPIO's nor the external ADC ref, so we should be good to go.