Optimum performance can only be achieved if the device is correctly supported. The very nature of a switching converter requires power to be instantly available when it switches on. If the converter has DMOS switching transistors, the fast edges will create a high current demand on the input supply. This transient load placed on the input is supplied by the external input decoupling capacitor, thus maintaining the input voltage. Therefore, the input supply does not see this transient (this is an analogy to high-speed digital circuits). The positioning of the capacitor is critical and must be placed as close as possible to the input pins and connected via a low-impedance path.

The optimum performance primarily depends on two factors:

• Connection of the input and output circuits for minimal loss.
• The ability of the decoupling capacitors to maintain the input and output voltages at a constant level.