To begin the design process a few parameters must be decided upon. The designer needs to know the following:

• Normal Input Operation Voltage
• Current Limit

Input and output capacitance improves the performance of the device; the actual capacitance must be optimized for the particular application. For all applications, TI recommends a 0.1-μF or greater ceramic bypass capacitor between IN and GND, as close to the device as possible for local noise decoupling. This precaution reduces ringing on the input due to power-supply transients. Additional input capacitance may be needed on the input to reduce voltage undershoot from exceeding the UVLO of other load share one power rail with TPS2042 device or overshoot from exceeding the absolute-maximum voltage of the device during heavy transient conditions. Preventing voltage undershoots and overshoots is especially important during bench testing when long, inductive cables are used to connect the evaluation board to the bench power supply. Output capacitance is not required, but TI recommends placing a high-value electrolytic capacitor on the output pin when large transient currents are expected on the output to reduce the undershoot, which is caused by the inductance of the output power bus just after a short has occurred and the TPS2042 device has abruptly reduced OUT current. Energy stored in the inductance drives the OUT voltage down and potentially negative as it discharges.