Clamping diodes are a fundametal part of modern integrated circuits. They provide a means of protecting the integrated circuit against circuit transients beyond the safe operating voltage of the chip and protect the chip against electrostatic discharge (ESD).

Useful Applications

There are applications for the clamping diodes that are outside of what they are originally designed for. The humble clamping diode can be used for high-to-low voltage translation. This is accomplished by placing a series resistor between the IC pin and the logic source. Another great way to use clamping diodes is for checking IC connectivity. Since the clamping diode forms a connection between any IO pin and ground, a multimeter can be used in diode mode between the anode (positive) and cathode (negative) of the IC. Note that this is reverse-biasing the IC from the ground pin, so the positive lead of the multimeter would go to the GND pin of the IC. This method was employed to check continuity in Brandon's CSP Fun project. The final use of a clamping circuit is to provide a baseline voltage for a capacitively coupled analog signal. This mostly falls within the realm of the input protection that clamping diodes were originally employed for at the beginning of this entry.