The fail-safe inputs incorporates internal ESD protection circuits on all pins. The fail-safe inputs have ESD protection from each pin to (V-) which allows these pins to exceed the supply voltage (V+) up to 40 V. If input voltages are to exceed 40 V, an external clamp would be required. Likewise, negative voltages on the inputs are ESD clamped to (V-) and should be limited to less than -0.1 V.

If the inputs are to be connected to a low impedance source, such as a power supply or buffered reference line, TI recommends adding a current-limiting resistor in series with the input to limit any transient currents should the clamps conduct. The current should be limited to 10 mA or less. This series resistance can be part of any resistive input dividers or networks.