The input pins of the INA333-Q1 are protected with internal diodes connected to the power-supply rails. These diodes clamp and prevent the applied signal from damaging the input circuitry. If the input signal voltage exceeds the power supplies by greater than 0.3 V, limit the input signal current to less than 10 mA to protect the internal clamp diodes. This current limiting is generally done with a series input resistor. Some signal sources are inherently current-limited and do not require limiting resistors.