2.2 Continuous vs Discontinuous Operation

In most Buck regulator applications, the inductor current never drops to zero during full-load operation (this is defined as continuous mode operation). Overall performance is usually better using continuous mode, and it allows maximum output power to be obtained from a given input voltage and switch current rating.

In applications where the maximum load current is fairly low, it can be advantageous to design for discontinuous mode operation. In these cases, operating in discontinuous mode can result in a smaller overall converter size (because a smaller inductor can be used).

Discontinuous mode operation at lower load current values is generally harmless, and even converters designed for continuous mode operation at full load will become discontinuous as the load current is decreased (usually causing no problems).