m51996ap Renesas Electronics Corporation., m51996ap Datasheet - Page 29

• Manufacturer Part Number: m51996ap
• Description: Switching Regulator Control
• Manufacturer: Renesas Electronics Corporation.

M51996AP/AFP
REJ03D0836-0201 Rev.2.01 Nov 14, 2007
Page 29 of 35
To change the knee point of frequency drop, use the circuit in figure 28.
To have a normal SOFT start function in the circuit in figure 27, use the circuit in figure 29. It is recommended
to use an R4 of 10 k .
Figure 29 Circuit to Use Frequency Drop During The Over Current and Normal Soft Start
V
OUT
Figure 28 Method to Control The Knee Point of Frequency Drop
Figure 27 Current to Lower Frequency During Over Current
F/B
F/B
SOFT
M51996A
M51996A
R2
R2
Photo-coupler
for feed back signal
R1
V
R1
Photo-coupler
for feed back signal
V
CC
CC
To make the knee point high
V
Q1 D1
Q1
OUT
REG
C
R
REG
SOFT
Collector
SOFT
Collector
D1
V
SOFT
V
SOFT R4
OUT
OUT
+
Q2
SOFT
+
+
C
C
R3
C
VCC
VCC
D2
D2
R3
To output transistor
C
Bias winding of
the main transformer
To output transistor
V
Bias winding of
the main transformer
OUT
To make the knee point low
SOFT