How do I protect the amplifier inputs from possible voltages above/below the supplies?
You must either clamp the input, or limit the current into the device, or ideally, both. The simplest way to limit this current is with a resistor selected such that the maximum voltage applied to the circuit input creates a current on the input pin that is less than the maximum pin current rating. A 1K to 100K resistor in series with the input pin is usually enough. The series resistor of an inverting configuration usually serves this function fairly well. However, a non-inverting amplifier may require this input protection resistor because the signal is usually applied directly to the non-inverting input pin. For low-impedance circuits that cannot contain a large resistance, a pair of clamping diodes between the negative rail, the input, and the positive rail, along with a small series resistance, will protect the device.
