Understanding PSoC GPIO specifications

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    Question: What are the maximum current capability and specifications of a GPIO pin?

     

    Answer:

    PSoC devices have multiple IOL/IOH specifications. Apart from per pin spec, there may be specifications for maximum source/sink current per side (even and odd pins) and also for total source/sink current for all I/Os. Refer the device speicific datasheet for the above specifications.

    As an example, consider CY8C29xxx devices. Here, as per the datasheet (38-12013 Rev. *N):

        Absolute maximum sink current on any one pin = 50mA

        Absolute maximum source current on any one pin = 25mA

        Maximum sink current spec = 25mA on one pin and 4 pins per side

        Maximum source current spec = 10mA on one pin and 4 pins per side

    Thus, maximum sink current on one side of the chip = 100mA (=25mA*4)

    Similarly, maximum source current on one side of the chip = 40mA (=10mA*4)

    So, you can source 20mA on one pin but will be limited to two pins sourcing 20mA on one side of the chip.

    Maximum sink current for the chip = 2 * 100mA for each side = 200mA

    Maximum source current for the chip = 2* 40mA for each side = 80mA