mb3769apf Fujitsu Microelectronics, Inc., mb3769apf Datasheet - Page 14

• Manufacturer Part Number: mb3769apf
• Description: Switching Regulator Controller
• Manufacturer: Fujitsu Microelectronics, Inc.

14
MB3769A
Overcurrent Protection Circuit
The waveform at the output FET source terminal is shown in Figure 11. The RC time constant must be chosen so that the voltage
glitch in the waveform does not cause erroneous overcurrent detection. This time constant is should be from 5 to 100 ns. A
detection current value depends on R or C because a waveform is weakened. To keep this glitch as small as possible, the
rectifiers on the transformer secondary winding must be the fast-recovery type.
0.1 F
APPLICATION EXAMPLE
12 to 18 V
220 pF
100 k
51 k
3.3 k
10 k
18 k
330 pF
Point S waveform
1+IN
2-IN
3FB
4DTC
5C
6R
7GND
8V
Fig. 11 - MB3769A Output FET Source Point
T
T
L
(OP)
(OP)
Fig. 10 - MB3769A DC - DC Convertor
Glitch
MB3769A
+IN
IN
V
OVP 13
OUT 9
V
REF
V
CC
V
(C)
(C)
10 k
H
Z
16
15
14
12
11
10
5.1 k
20 k
R
C
1
S
3.6 k
2.4 k
5 V
1 A