Datasheet

LTC3900
13
3900fb
3900 TA02
16
15
14
13
12
11
10
9
COMP
FB = 1.23V
R
OSC
SYNC
MAXDC
V
R
= 2.5V
SD
GND
S
OUT
V
IN
OUT
PGND
DELAY
OC
I
SENSE
BLANK
1
2
3
4
5
6
7
8
LT1952-1
Si7462
22k
S
OUT
100pF
145k
10k10k
47k
Q2 Q3
Q2, Q3, Q4, Q5 = Si7850
L1: DRQ127-220
V
OUT2
24V
2A
V
OUT1
12V
2A
V
OUT1
L1A
0.030R
13.3k
340k
22k
V
U1
V
FB
1µF
82k
680Ω
56k
0.47µF
0.1µF
1.2k
V
FB
BC857BF
33k
115k
V
IN
T1
PA1577
BAS516
BAS516
150µF
16V
33µF
16V
BAS516
BAS516
470R
F
G
BCX56
PDZ10B
1.5mH
0.1µF 0.1µF
V
U1
2
1
7
9
2.2µF
V
IN
36V TO 72V
V
IN
V
U1
1µF
82k
•
3
4
•
•
•
C
G
•
Q4 Q5
L1B
F
G
8
10
•
C
G
V
OUT1
1k
•
+
560R
PE-68386
S
OUT
BCX55
PDZ7.5B
PS2801-1 LT4430
V
AUX
FG
470pF
220pF
CG
V
AUX
1µF
3.92k
5.23k
100k
33pF
15nF
LTC3900
38.3k
10k
10k
CS
+
CS
–
CG
V
CC
SYNC
TIMER
GND
FG
1
2
3
4
8
7
6
5
•
•
V
CC
GND
OC
OPTO
COMP
FB
1
2
3
6
5
4
Typical applicaTions
36V to 72V Input to 12V and 24V (or ± 12V), 2A Output Converter in 1/8th Brick Footprint
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
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.