Datasheet

18
LTC1698
1698f
APPLICATIO S I FOR ATIO
WUUU
CG
V
DD
LTC1698
PGND
GND
OPTODRV
V
COMP
MARGIN
C
FB
R1
BOLD LINES INDICATE HIGH CURRENT PATHS
R
C
C
C
V
FB
SYNC
FG
V
AUX
I
COMP
I
SNS
I
SENSGND
PWRGD
OVPIN
2
1
3
4
5
6
7
8
15
16
C
OUT
V
OUT
+
V
OUT
–
14
13
12
11
10
9
R2R7
D3
R
SECSEN
Q4
C
K
R
K
MOC207
C4
0.1µF
R4
1698 F09
1k
0.1µF
4.7µF
T2
T1
0.1µF
C
CILM
R
CILM
R5
1k
+
Q3
1Ω
L1
• •
• •
Figure 9. LTC1698 Layout Diagram
Figure 10. Simplified Single Secondary Winding 3.3V and 1.8V Output Isolated DC/DC Converter
V
COMP
V
DD
LTC1698
GND
V
FB
CG
FG
I
SNS
SYNC
OPTODRV
V
CC
BIAS
L1
V
OUT1
3.3V
AT 10A
BG
LT3781
SG
ISOLATION
BOUNDARY
C
OUT2
: POSCAP, 680µF/4V
L2: SUMIDA CEP125-IR8MC-H
Q1, Q2: SILICONIX Si7440DP
1698 F10
V
IN
36V
TO 72V
V
REF
V
C
V
FB
TG
••
GBIAS
4.7µF
CMDSH-3
Q1
Q2 B340A
3.01k
2.32k
L2
1.8µH
0.006Ω
V
CC
BOOST
CL
–
CL
+
LT3710
SYNC
TG
CSET
ILCOMP
SS
••
–
+
0.1µF
3.3k
33nF
10pF
C
S
680pF
10k
10k
180pF
0.01µF
BGS
PGND
SW
BG
VA
OUT
V
FB
4700pF
V
OUT2
1.8V
AT 10A
C
OUT2
+
220Ω