Datasheet

17
LT1681
1681f
C1: MURATA ERIE GHM3045X7R222K-GC C2, C3, C4: VITRAMON VJ1825Y155MXB C5 TO C8: 330µF 10V KEMET T510X337K010AS
OR 330µF 6.3V KEMET T520D337M006AS
C26: AVX TPSE686M020R0150 ISO1: FAIRCHILD MOC207 L1: COILCRAFT DO1608C-332 L2: PULSE P1977 PLANAR INDUCTOR L3: COILCRAFT DO1608C-105 Q1, Q3: SILICONIX Si4486EY Q5, Q6, Q14,Q15,Q17: FAIRCHILD FDS6680A Q7: FAIRCHILD NDT410EL Q12: ZETEX ZVN3310F Q13: ZETEX FZT690 T1: PULSE P1976 PLANAR TRANSFORMER
(FUNCTIONAL INSULATION) OR PULSE PA-0191 (BASIC INSULATION)
T2: MIDCOM 31264R (FUNCTIONAL INSULATION) OR
MIDCOM 31323R (BASIC INSULATION)
V
CC
14
2 1
5
1µF 82pF
OVLO SHDN
1.24k
1%
73.2k
1%
20k
24k
10k
267k
0.25W
C26
68µF
20V
56k
5V
REF
6
F
SET
4700pF
8
SS
10 15
BAS21
BAT54
T2
S
S
BAS21
BAT54
BAT54
Q12 ZVN3310F
9
V
C
PGND
12
I
MAX
V
FB
374
THERM
LT1681SW
SYNC SGND
52.3k
1%
10Ω
1k
3k
1k
1k
100Ω
9V
10k
2k
0.25W
Q13
FZT690
4.7µF
16V
0.22µF 50V
S
MMBZ5240BLT1 10V
1
3.3Ω
10k
5V
REF
ISO1
MOC207
7
143
3 1
4 6
5
14 15
6 5
82
3300pF
4700pF
0.1µF
5V
REF
13
SG
+
0.1µF
1nF
11
SENSE
16
BG
18
BSTREF
19
TG
17 20
BAS21
0.1µF 100V
L3 1mH
BLKSENS
MMBZ5245LT1
15V
V
BST
220pF
C4 1.5µF 100V
C3 1.5µF 100V
L1
3.3µH
0.022µF
1000pF
••
SYNC V
FB
OVPIN
MARGIN
I
COMP
V
DD
OPTODRV V
AUX
0.1µF
12
I
SNS
11
I
SNSGND
16
FG
2
CG
PGND GND
LTC1698
PWRGD
6
8 9 7 13
1.24k
1%
1.78k 1%
3.01k 1%
SENSE
+
SENSE
–
TRIM
100Ω 0.25W
5
6
4
2 3
1
7
9V
V
OUT
+
2.43k 1%
1043
V
COMP
1698 F12
3.01k
1%
3.01k
1%
3.01k
1%
3.01k 1%
100Ω 0.25W
1k
0.33µF
MBR0530
0.025Ω
1/2W
3 4
Q3
1000pF
100V
C1
2200pF
250V
1000pF 100V
Q5, Q14
FDS6680A
×2
Q6, Q15, Q17 FDS6680A ×3
MURS120T3
MURS120T3
10Ω
2
7
V
SEC
5
•
••
1
Q1
T1
10Ω
MMBT3906LT1
MMBT3906LT1
V
IN
+
V
IN
–
C2 1.5µF 100V
V
OUT
+
V
OUT
–
S
C5 TO C8 330µF
10V ×4
10Ω
0.25W
10Ω
0.25W
4.7Ω
L2
2.35µH
330pF
+
MMBT3906LT1
62k 0.25W
MMBZ5248LT1 18V
MMBT3904LT1
47k
4.7µF
5V
REF
MMBD914LT1
Q7
NDT410EL
1.5k
0.25W
1.5k
0.25W
–
+
LT1006S8
Figure 9. 36V-72V DC in to 3.3V/20A Isolated Synchronous Forward Converter with Fast Start and Differential Sense
TYPICAL APPLICATIO S
U