AC-DC Desktop Power Factor Correction
The environmental and economic benefits of power factor correction (PFC) and harmonic current reduction have led
to standard requirements (e.g. IEC1000-3-2 and EN 61000-2-3) in most power supply designs. Typically, two-control
strategies are used to drive the "boost" cell, which implements power factor correction - continuous current mode
(CCM) or discontinuous current mode (DCM) - and are generally selected for the power level of the application.
In DCM, (70W to 250W) the PFC switch is turned on only when the inductor current reaches zero.
In CCM (upwards from 200W), the MOSFET is turned on when inductor current is above zero.