It is required to protect the power path on the PD controller from voltage transients that violate the absolute maximum ratings in the data sheet. This helps prevent a system from being damaged in the field. For an external power path, it is recommend to use components that have a voltage rating similar to the PD controller or better to ensure it does not fail due to overvoltage conditions. It is also highly recommended to protect the external power path with reverse current protection (RCP).

For VBUS, it is recommended to place a Schottky diode on the VBUS to absorb GND currents during short or sudden disconnect events. The Schottky diode protects all of the devices connected to the VBUS and absorbs the current when the VBUS falls below GND. The forward voltage for the Schottky diode must be as low as possible (recommended 500 mV or lower) to protect the internal diodes of the devices connected to the VBUS. Better alternatives to a Schottky diode like a uni-directional Transient Voltage Suppressor (TVS) device, such as the TVS2200, may be used to protect against overvoltage conditions and GND currents. The forward voltage of the TVS device must also be as low as possible.

When connecting an external power supply (barrel jack) directly to the PPHV1 and PPHV2 paths, it is crucial to protect the power path from transient voltages caused by a hot plug. At minimum, expect to see double the external power voltage during the hot plug (up to 40 V for a 20 V barrel jack). Proper system design must include minimizing the transient voltage to protect the power paths of the PD controller and other devices directly connected to the external supply. There are various protection designs that can be considered: Input power filter (Ferrite Bead and Capacitor), soft-start circuit (Power FET), or input power filter with TVS. For external supplies with very high output capacitance, a combination of these protection schemes may be required. It is also important to have the necessary PPHV1 and PPHV2 bulk capacitance to meet the source requirements and PD specification.

The best practice for supplying power to the PPHV1 and PPHV2 paths is to use a regulated controlled supply. For systems that support 5 V only, the system 5-V supply can be connected directly as long as the turn-on ramp rate is controlled. In the case for systems that supply up to 100 W (5 V/9 V/15 V/20 V), a variable DC/DC converter feeds directly into the PPHV1 and PPHV2 paths, which is also a controlled ramp rate. It is required that the power supplies connected to PPHV1 and PPHV2 (DC/DC or AC/DC converters) do not violate the absolute max voltage ratings of the PD controller.