Datasheet

LT1947
8
1947fa
OPERATIO
U
Figure 4. Start-Up Waveforms
with Soft-Start Circuit Added
5ms/DIV 1947 F04.tif
V
SS
5V/DIV
V
ON
20V/DIV
AV
DD
10V/DIV
V
OFF
10V/DIV
SW2
D2
V
IN
SW1
L1
3.3µH
L2
4.7µH
D1
D3 D4
SHDN
C
T
LT1947
GND
V
O2
R3
182k
R1
53.6k
C2
3.3µF
CERAMIC
×2
C1: TAIYO YUDEN LMK316BJ225MD
C2: TAIYO YUDEN LMK325BJ335MD ×2
C3: AVX 0.22µF 25V X7R
C4, C6: TAIYO YUDEN LMK107BJ684MA
C4
0.68µF
CERAMIC
C6
0.68µF
AV
DD
8V
200mA
V
ON
24V
10mA
V
OFF
–8V
10mA
R2
10k
1947 F03
R4
10k
FB1
V
ON
C5
10nF
C3
220nF
C1
2.2µF
CERAMIC
V
IN
FB2
D1: MBRM120LT3
D2: CMDSH-3
D3, D4: BAT54S DUAL DIODE
L1: SUMIDA CLQ4D103R3
L2: TAIYO YUDEN LB2012B4R7M
C
SS
33nF
V
SS
R
SS
33.2k
V
OFF
Figure 3. R
SS
and C
SS
at SHDN Pin Provide Soft-Start