Hi, Venkatesh,
The source current means the GPIO outputting current when the GPIO pin outputs logic high, the higher the source current is, the higher voltage drop is. The 4mA current means that we can guarantee that the voltage drop is less than 400mV when the source current is 4mA.
I copy the Fig from the data sheet of LPC177x. which can be downloaded from the link:
https://www.nxp.com.cn/docs/en/data-sheet/LPC178X_7X.pdf
The sink current is the current the pin draws when the GPIO pin outputs LOW logic. The higher the sink current is, the higher the GPIO pin voltage is. The 4mA sink current means that we can guarantee the pin voltage rising is less than 400mV when the pin draws 4mA current.
Hope it can help you
Hi, Venkatesh,
The source current means the GPIO outputting current when the GPIO pin outputs logic high, the higher the source current is, the higher voltage drop is. The 4mA current means that we can guarantee that the voltage drop is less than 400mV when the source current is 4mA.
I copy the Fig from the data sheet of LPC177x. which can be downloaded from the link:
https://www.nxp.com.cn/docs/en/data-sheet/LPC178X_7X.pdf
The sink current is the current the pin draws when the GPIO pin outputs LOW logic. The higher the sink current is, the higher the GPIO pin voltage is. The 4mA sink current means that we can guarantee the pin voltage rising is less than 400mV when the pin draws 4mA current.
Hope it can help you