The forced PWM option is choiced for cases when constant frequency operation is more important than light-load efficiency.

In FPWM operation, the diode emulation feature is turned off. This means that the device remains in CCM under light loads. Under conditions where the device must reduce the on time or off time below the compliant minimum to maintain regulation, the frequency reduces to maintain the effective duty cycle required for regulation. This occurs for very high and very low input and output voltage ratios. In FPWM mode, a limited reverse current is allowed through the inductor, allowing power to pass from the output of the regulator to the input of the regulator. Note that in FPWM mode, larger currents pass through the inductor, if lightly loaded, than in auto mode. After loads are heavy enough to necessitate CCM operation, FPWM mode has no measurable effect on regulator operation.