Electrostatic discharge (ESD) protection followed by back-to-back diodes and input resistors (see Figure 7-7) are used for input protection on the OPA564-Q1. Exceeding the turn-on threshold of these diodes, as in a pulse condition, can cause current to flow through the input protection diodes because of the finite slew rate of the amplifier. If the input current is not limited, the back-to-back diodes and the input devices can be destroyed. Sources of high input current can also cause subtle damage to the amplifier. Although the unit can still function, important parameters such as input offset voltage, drift, and noise can shift.

When using the OPA564-Q1 as a unity-gain buffer (follower), as an inverting amplifier, or in shutdown mode, limit the input voltage between the input terminals (+IN and –IN) so that the voltage does not exceed 0.5V. Maintain this condition across the entire common-mode range from V– to V+. If the inputs exceed either supply rail, limit the current to 10mA through the ESD protection diodes. During excursions past the rails, limit the voltage across the input terminals. If necessary, add external back-to-back diodes between +IN and –IN to maintain the 0.5V requirement between these connections.