Specifically, sinking a Cree C503B green LED (Vf 3.2V at 20ma) from a GPIO configured for high drive, without a current limiting resistor, from VDD 3.6V?
Figure 23 “GPIO drive strength vs Voltage, high drive VDD=3.0V” of the nrf52832 product spec, seems to show that the voltage drop across the GPIO rises with current. My reasoning is that the circuit would stabilize at about 0.5V drop across the GPIO, 3.1V across the LED, and 13mA current. I know an LED should be driven from a constant current source, is a GPIO in some sense regulating the current, at least in this circuit? I am not a electrical engineer.
