ON Semiconductor – NCP1602: Power Factor Controller with Enhanced Light-Load Efficiency


The NCP1602 PFC controller is designed to drive PFC boost stages. It is based on an innovative Valley Synchronized Frequency Fold-back (VSFF) method. In this mode, the circuit classically operates in Critical conduction Mode (CrM) when control voltage exceeds

a programmable value Vctrl, FF. When Vcontrol is below this preset level Vctrl, FF, the NCP1602 (versions [B**] and [D**]) linearly decays the frequency down to about 30kHz until Vcontrol reaches the SKIP mode threshold. VSFF maximizes the efficiency at both nominal and light- load. In particular, the stand-by losses are reduced to a minimum. Housed in a TSOP6 package, the circuit also incorporates the features necessary for robust and compact PFC stages, with few external components.

• Near-unity power factor
• Valley synchronized frequency fold-back (VSFF)
• On-time modulation to maintain a proper current shaping in VSFF mode
• Fast line/load transient compensation
• -500mA/+800mA drive capability
• Two-level boost follower line level dependent
• Works with or without a transformer w/ZCD winding
• Skip mode at very low load current
• Valley turn-on
• 9.5V to 30V VCC range