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AM3352: GPIO drive capability

Lauren Mayfield
Expert 7915 points
Part Number: AM3352

Hi,

I'm asking this question on behalf of my customer.

"

I have  question about GPIO drive ability, my project use am3352, have EMMC/SD/DDR3/dual-Ethernet and use most of pings.

I have 12 LEDs to indicate system status. drive current for each LED is about 3mA, I plan to use 12 GPIO to drive those 12 LEDs.

Is it OK for AM3352 to drive those 12 LEDs? Which is better: High (drive) or Low (sink) active?

"

My initial thoughts are that he should be fine with the amount of current since the maximum current that can be driven in each GPIO pin is 6mA, but I'm not sure whether high or low is better.

Thanks!
Lauren

  • 0
    TI__Guru**** 393215 points

    Hi Lauren,

    Lauren Mayfield said:
    My initial thoughts are that he should be fine with the amount of current since the maximum current that can be driven in each GPIO pin is 6mA

    This is only partially true. Customer must consider also the maximum allowed current on each VDDSHVx rail (Table 5-10 in the AM335x Datasheet Rev. K.

    Lauren Mayfield said:
    I'm not sure whether high or low is better.

    If the LEDs are connected directly to the GPIO pins, then driving them low is the better choice, as there will be no extra power drawn from the VDDSHVx rails. However in my opinion the best solution is to buffer the GPIOs externally (e.g. by transistors), as this will eliminate these 36mA of extra current into the processor. 

  • 0
    TI__Guru**** 393215 points

    Hi Lauren,

    Lauren Mayfield said:
    My initial thoughts are that he should be fine with the amount of current since the maximum current that can be driven in each GPIO pin is 6mA

    This is only partially true. Customer must consider also the maximum allowed current on each VDDSHVx rail (Table 5-10 in the AM335x Datasheet Rev. K).

    Lauren Mayfield said:
    I'm not sure whether high or low is better.

    If the LEDs are connected directly to the GPIO pins, then driving them low is the better choice, as there will be no extra power drawn from the VDDSHVx rails. However in my opinion the best solution is to buffer the GPIOs externally (e.g. by transistors), as this will eliminate these 36mA of extra current into the processor.