A protection cell for a cell library. The protection cell defines a protection circuit for an IC having a driving device with a first supply voltage Vdd1 and an output, and a driven device having an input and a second supply voltage Vdd2. The protection circuit includes a first device from the group consisting of a P-diode and a gate-Vdd PMOS. The first device is coupled between a first power bus connected to Vdd2 and the input of the driven device. The input of the driven device is coupled by way of a resistor to the output of the driving device. A second device corresponding to the first device is provided, from the group consisting of an N-diode and a grounded gate NMOS. The second device is coupled between the input of the driven device and a ground bus.