MB3769A Datasheet, PDF (13/26 Pages) Fujitsu Component Limited. – SWITCHING REGULATOR CONTROLLER

MB3769A
s APPLICATION EXAMPLE
12 to 18 V
Fig. 10 - MB3769A DC - DC Convertor
0.1 µF
3.3 kΩ
10 kΩ
1+IN (OP)
2-IN (OP)
+IN (C) 16
IN (C) 15
100 kΩ
330 pF
3 FB
4 DTC
VREF 14
OVP 13
5CT ^MB3769A VCC 12
6 RT
VZ 11
7 GND
VH 10
8 VL
OUT 9
20 kΩ
220 pF
51 kΩ _{18 kΩ}
10 kΩ _{5.1 kΩ}
R
S
C
1Ω
5V
1A
3.6 kΩ
2.4 kΩ
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.
Fig. 11 - MB3769A Output FET Source Point
Glitch
Point S waveform
13