Pull Up and Pull Down Resistor Circuits
In this article, we go over the pull up and pull down resistors circuits.
Pull Up Resistor Circuit: A pull up resistor pulls a pin of a chip up to a HIGH state, so that it is normally HIGH unless intentionally brought LOW. Connect the resistor to the positive voltage, all of the voltage from the power supply drops across the resistor. When the switch is closed, the pin makes direct contact with ground and it becomes LOW.
Pull Down Resistor Circuit: A pull down resistor pulls a pin of a chip down to a LOW state, so that it is normally LOW unless intentionally brought HIGH. The pin of this chip will be LOW normally and when the switch is closed becomes HIGH. That’s because when the switch is open, it is connected directly to ground. Therefore, it is at a logic LOW level. When the switch is closed, the voltage from the power supply falls across the resistor. Thus, the pin of the chip is drawn to a HIGH state.