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DAC7718: GPIO Pins

Jonas Schulz
Prodigy 135 points
Part Number: DAC7718

Hi all, I have two questions regarding the GPIO Pins.

  1. I'm trying to desing the startup sequence and was wondering if the GPIO Pins and SPI registers are already available without the analog power supply (AVDD), so that I can use one GPIO from the DAC7718 to Power Up his own analog power supply (AVDD) via the Microcontroller and the SPI register of the DAC7718.
  2. I want to clearify if I understand that correctly: If the devices power up(or is off) the GPIO pins are tied to high-impedance. So when I'm using pull-up resistor there is the power supply voltage (IOVDD) on the GPIO Pin if the device is turned off? And I can only set them active to low --> 0V 

Best Wishes

Jonas

  • 0
    TI__Guru 53573 points

    Hi Jonas,

    If any of the supply inputs are below the recommended supply range, the device is still likely in a reset state.  This means that if the AVDD supply is off, the device will not respond to any commands and the GPIO will likely not change states. 

    2. If the device is in the reset state, the GPIO pins should be high-z.  If the IOVDD supply for the GPIOs is off, then they are actually connected to DVDD (and GND) by the ESD diode, meaning that it will be relatively low impedance.  So in you case, if IOVDD is supplied, and there is a pull up on the GPIO to IOVDD, then I would expect the voltage to be the same as IOVDD.