Abstract

All operational amplifier (op amp) input stages feature some sort of protection against electrostatic discharge (ESD). Most amplifiers accomplish this with diodes from both inputs and the output to both supply rails. While these diodes offer protection against ESD strikes, the diodes can also lead to undesirable current through the ESD structure when one, or both, of the inputs exceeds the V+ rail. Fortunately, there are a select few op amps with an alternative input ESD structure designed to prevent this undesired current. This application report covers the standard ESD protection structure and an alternative ESD protection structure. The document also shows different testing methods for observing the behavior of the ESD protection under device shutdown and measurement data from devices with protection structures that do not have diodes from the inputs to the V+ supply pin.