CM6802AXIP datasheet(21/25 Pages) CHAMP

21 / 25 page

CM6802A/B/AH/BH (Dynamic Soft PFC/Green PWM)

http://www.championmicro.com.tw

EPA/80++ ZVS-Like PFC/PWM COMBO CONTROLLER

Design for High Efficient Power Supply at both Full Load and Light Load

2009/11/02 Rev. 1.4

Champion Microelectronic Corporation

In case of leading edge modulation, the switch is turned

OFF right at the leading edge of the system clock. When the

modulating ramp reaches the level of the error amplifier output

voltage, the switch will be turned ON. The effective duty-cycle

of the leading edge modulation is determined during OFF time

of the switch.

Figure 5 shows a leading edge control scheme.

One of the advantages of this control technique is that it

required only one system clock. Switch 1(SW1) turns off and

switch 2 (SW2) turns on at the same instant to minimize the

momentary “no-load” period, thus lowering ripple voltage

generated by the switching action. With such synchronized

switching, the ripple voltage of the first stage is reduced.

Calculation and evaluation have shown that the 120Hz

component of the PFC’s output ripple voltage can be reduced

by as much as 30% using this method.

CM6802AXIP Datasheet(PDF) 21 Page - Champion Microelectronic Corp.