LTC3705_15 Datasheet, PDF (17/20 Pages) Linear Technology – 2-Switch Forward Controller and Gate Driver

TYPICAL APPLICATIO S
LTC3705
V_IN+
L1 1µH
1µF
100V
1µF
100V
x3
Si7852DP
Si7852DP
MURS120
T1
••
9:2
Si7336ADP
MURS120
1nF
100V
10Ω
0.25W
1nF
100V
10Ω
0.25W
L2 1.2µH
1.2Ω
Si7336ADP
×2
1µF
CMPSH1-4
V_IN–
365k
1%
1nF
15k
1%
30mΩ
1W
2.2nF
250V
2mΩ
2W
10µF
25V
100Ω
100k
680pF
FQT7N10
BAS21 ^0.22µF
NDRV
BOOST TG TS BG IS
L1: VISHAY IHLP-2525CZ-01
L2: COILCRAFT SER2010-122
T1: PULSE PA0807
T2: PULSE PA0297
UVLO
LTC3705
FB/IN⁺
100Ω
T2
0.1µF ^{• •}
2.2µF
25V
V_CC
SS/FLT
FS/IN^–
GND PGND VSLMT
470pF
5k
2:1
33nF
162k
33nF
100Ω 100Ω
1nF
1µF
FG SW
I_S–
I_S+
PT⁺
CZT3019
2.2µF
16V
SG V_IN
LTC3706
NDRV V_CC
FS/SYNC
FB
ITH
PT^–
RUN/SS GND PGND PHASE SLP MODE REGSD 680pF
100k
20k
V_OUT+
330µF
6.3V
×3
V_OUT–
102k
1%
22.6k
1%
3705 F06
V_OUT
50mV/DIV
Load Step
Efficiency
95
V_IN = 36V
90
I_OUT
10A/DIV
20µs/DIV
V_IN = 48V
V_OUT = 3.3V
LOAD STEP = 0A TO 20A
3705 F06b
V_IN = 72V
85
80
0
5
10
15
20
25
LOAD CURRENT (A)
3705 F06c
Figure 6. 36V-72V to 3.3V/20A Isolated Forward Converter Using LTC3706
3705fb
17