1. Introduction
The FAN7527 is an active power factor correction(PFC)
controller for boost PFC application which operates in the
critical conduction mode. It turns on MOSFET when the
inductor current reaches zero and turns off MOSFET when
the inductor current meets the desired input current reference
voltage as shown in Fig. 1. In this way, the input current
waveform follows that of the input voltage, therefore a good
power factor is obtained.
1-1. Internal Block Diagram
It contains following blocks.
• Error amplifier (E/A)
• Zero current detection (Idet)
• Switch current sensing (CS)
• Input voltage sensing (MULT)
• Switch drive (OUT)
