What is a pull-up resistor? Pull-up resistance and pull-down resistance are resistance components, the so-called pull-up resistance is connected to the positive electrode of the power supply, and the pull-down is connected to the negative electrode or ground. Pull-up is to pass an uncertain signal through a resistor clamp at a high level, and the resistor acts as a current limiting function. Similarly, a pull-down also puts an uncertain signal through a resistor clamp at a low level.

    So, what are the uses and differences between pull-up and pull-down resistors?

    Pull-up is to pass an uncertain signal through a resistor clamp at a high level, and the resistor acts as a current limiting function. The pull-down resistor is directly connected to the ground, and the end of the resistor is low when the diode is connected, and the uncertain signal is placed at the low level through a resistor clamp. Pull up is the input current to the device, pull down is the output current; Strength is only the resistance value of the pull-up resistor is different, there is no strict distinction; For non-collector (or drain) open output circuit (such as ordinary gate circuit) to provide current and voltage ability is limited, the function of the pull-up resistor is mainly for the collector open output circuit output current channel.