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AM335x - Caution during a Hardware RESET - GPIOs Feedback powered

RNJ
Prodigy 45 points

Hello guys!!

In my project we are planning to Reset the MPU indirectly by the PMIC (TPS65910AA1) turning OFF/ON by the PWRHOLD Pin on PMIC.

During the reset I can assume there is no voltage in the PMIC's suppliers, however in some cases I will have a few GPIOs powered by another suppliers (external pullups, etc). Is there any problem to use this Reset allowing a feedback supply on the processors by these GPIOs? Or should I remove any external voltage on the processor before start a Reset procedure to avoid electrical overstress on the MPU?

  • 0
    TI__Guru 63145 points

    This requirement is defined in the Absolute Maximum Rating table found in the AM335x data sheet.  The parameter is "Steady state max voltage at all IO pins", and the value is "–0.5 V to IO supply voltage + 0.3 V" with the following note. 

    This parameter applies to all IO terminals which are not fail-safe and the requirement applies to all values of IO supply voltage. For example, if the voltage applied to a specific IO supply is 0 volts the valid input voltage range for any IO powered by that supply will be –0.5 to +0.3 V. Apply special attention anytime peripheral devices are not powered from the same power sources used to power the respective IO supply. It is important the attached peripheral never sources a voltage outside the valid input voltage range, including power supply ramp-up and ramp-down sequences.

    Regards,
    Paul