LTC3721-2 LINER [Linear Technology], LTC3721-2 Datasheet - Page 13

• Manufacturer Part Number: LTC3721-2
• Description: Synchronous Rectifier Driver for Forward Converters
• Manufacturer: LINER [Linear Technology]

Typical applicaTions
The LTC3900 can drive multiple synchronous output
rectifiers. The 12V and 24V or ±12V output converter
has good cross regulation due to low voltage drops in
1.2k
V
Q2, Q3, Q4, Q5 = Si7850
FB
0.1µF
13.3k
BC857BF
22k
340k
V
IN
115k
33k
22k
36V to 72V Input to 12V and 24V (or ± 12V), 2A Output Converter in 1/8th Brick Footprint
36V TO 72V
1
2
3
4
5
6
7
8
COMP
FB = 1.23V
R
SYNC
MAXDC
V
SD
GND
R
OSC
= 2.5V
56k
V
IN
0.47µF
2.2µF
LT1952-1
BLANK
DELAY
I
PGND
SENSE
S
OUT
OUT
V
OC
82k
IN
16
15
14
13
12
11
10
9
BCX56
PDZ10B
680
82k
V
S
V
U1
FB
OUT
100pF
145k
1.5mH
V
U1
Si7462
PS2801-1
1µF
V
IN
V
U1
V
OUT1
BAS516
1k
0.030R
PDZ7.5B
BAS516
470R
2
1
3
4
PA1577
•
•
T1
the output MOSFETs. Other combinations like 3.3V and
–5V or 1.5V and 5V can be easily achieved by changing
the transformer turns ratio.
BCX55
•
•
V
7
9
8
10
F
AUX
G
V
AUX
0.1µF
10k
1µF
F
10k
10k
G
CG
1
2
3
V
GND
OC
CC
BAS516
LT4430
1
2
3
4
1µF
COMP
CS
CS
CG
V
OPTO
CC
LTC3900
+
–
FB
Q2
Q4
38.3k
TIMER
6
5
4
C
SYNC
GND
G
FG
3.92k
5.23k
0.1µF
L1: DRQ127-220
47k
10k
8
7
6
5
C
G
FG
15nF
33pF
100k
BAS516
470pF
560R
Q3
Q5
L1A
L1B
V
OUT1
PE-68386
LTC3900
+
•
150µF
16V
33µF
16V
•
V
24V
2A
V
12V
2A
220pF
OUT2
OUT1
13
3900 TA02
S
OUT
3900fb