Understanding PSoC GPIO specifications | Cypress Semiconductor
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Understanding PSoC GPIO specifications
What are the maximum current capability and specifications of a GPIO pin?
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