As Figure 8-1 shows, all device pins are protected with internal ESD protection diodes to the power supplies. These diodes provide moderate protection to input overdrive voltages above the supplies. The protection diodes can typically support 10-mA continuous input and output currents. Use series current limiting resistors if input voltages exceeding the supply voltages occur at the amplifier inputs, which ensures the current through the ESD diodes remains within their rated value. Keep these resistor values as low as possible because using high values degrade noise performance and frequency response.
Since OPAx863 is a bipolar amplifier, the two inputs are protected with anti-parallel back-to-back diodes between them which limits the maximum input differential voltage to approximately 1 V. In very fast input or output transient conditions, the amplifier is slew limited and the two inputs are pulled apart up to 1 V, when the anti-parallel diodes begin to conduct. Care must be taken to use gain-setting and feedback resistors large enough to limit the current through these diodes in such conditions.