M51995AP/AFP
M51995A
VOUT
RVFFB
VF
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,
To VF
To VF
To VF
From
VOUT
From
VOUT
From
VOUT
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.
Point that VCC voltage
or third winding
voltage decreases
under "Operation-Stop Voltage"
DC Output Current
Figure 35 Over Current Limiting Curve on Fly Back System
VCC
Collector
VF
R1
R2
+
M51995A
CVCC
Figure 36 Circuit Diagram to make Knee Point Low on Fly Back System
REJ03D0835-0300 Rev.3.00 Jun 06, 2008
Page 34 of 40
RENESAS [ RENESAS TECHNOLOGY CORP ]
