FA7711V Datasheet, PDF (21/25 Pages) Fuji Electric – FUJI Power Supply Control IC

3.7V
FA7711V
Rcs3
100k
CS3
0.1uF
ex. 17V
4.7k
Maxim um source
current :
185u A(typ .)
24
IN3+
23
22
IN3- FB3
21
IN2+
20
19
IN2- FB2
18
17
16
15
14
13
VCC PVCC CS3 OUT3 CS2 OUT2
FA7711V
CP
IC1 1
RT SEL3 VREF SEL2 IN1+ IN1- FB1 GND PGND CS1 OUT1
2
3
4
5
6
7
8
9
10
11
12
CP RT
0.1uF 18k
REF
2.2uF
4.7n
4.7k
Maxim um
source
current :
185u A(typ .)
3.7V
Rcs1
100K
CS1
0.1uF
R58 : 100k
R54 R55
1k
200k
ch3:1.2V /0V
R56
1M
QFB3 QCS3 QA3
R57 : 100k
R51 R52
1k
200k
ch1:1.2V /0V
R53
1M
QFB1 QCS1 QA1
Fig.15 ON/OFF Circuit
Note : Channel 2 to control OUT2 pin is not
suitable for ON/OFF control.
QA1, QA3:
Assuming base voltage as 0.9 V ( max. ),
R59, R60, R61 and R62 should be designed so that the
base current are larger than each collector current /
20.
Here, 20 means fully small hFE in order to
obtain low saturation voltage of QA*.
R51, R54 :
The voltage drop should be lower than 0.5 V at FB1
pin or FB3 pin to obtain 0% duty for ON mode of
QFB*.
ex. R51 * ISOFB = 1k ohm * 185 uA
= 0.185 V
< 0.5 V
Fuji Electric Systems Co., Ltd.
AN-060E Rev.1.0
21
Jun-2010
http://www.fujielectric.co.jp/fdt/scd/