M51995AFP datasheet(34/41 Pages) RENESAS

34 / 41 page

M51995AP/AFP

REJ03D0835-0201 Rev.2.01 Nov 14, 2007

Page 34 of 40

M51995A

VOUT

RVFFB

CVFFB

Figure 33 Feed Back Loop through Low Pass Filter from VOUT to VF Terminal

Figure 34 shows how to control the knee point where the frequency becomes decrease,

From

VOUT

To VF

From

VOUT

To VF

From

VOUT

To VF

To make the knee

point high

To make the knee

point low

Figure 34 How to Control the Knee Point

(2) In case of fly back system

The DC output voltage of SMPS depends on the VCC Voltage of type M51995A when the polarity of the third

winding is negative and the system is fly back. So the operation of type M51995A will stop when the VCC

becomes lower than “Operation-stop voltage” of M51995A when the DC output voltage of SMPS decreases

under specified value at over load condition.

DC Output Current

Point that VCC voltage

or third winding

voltage decreases

under "Operation-Stop Voltage"

Figure 35 Over Current Limiting Curve on Fly Back System

M51995A

VCC

Collector

CVCC

Figure 36 Circuit Diagram to make Knee Point Low on Fly Back System

M51995AFP Datasheet(PDF) 34 Page - Renesas Technology Corp