A push-button switch is connected to a microcontroller port input, using an external pull-up resistor. The supply voltage is 3.3 V.
(a) Sketch the circuit of this arrangement.
(b) As it is a power-conscious application, the current drawn when the switch is closed should not be more than 20 microamps. What is the minimum pull-up resistor value?
(c) The port input is known to have a worst-case input leakage current of 5 microamps, flowing into the input. What is the actual input voltage for the resistor value calculated above when the switch is not pressed?