Datasheet

5
LTC1649
BLOCK DIAGRA
W
–
+
–
+
I
LIM
FB MIN
PWM
MAX
+
40mV
+
1.26V
12µA
+
40mV
12µA
PV
CC1
CP
OUT
C
+
SHDN
COMP
SS
I
MAX
V
CC
PV
CC2
G1
G2
I
FB
FB
1649 BD
INTERNAL
SHUTDOWN
50µs
DELAY
V
IN
CHARGE
PUMP
C
–
TEST CIRCUIT
Figure 1
V
CC
V
OUT
2.5V
I
MAX
SHDN
1µF
G2
FB
V
IN
V
IN
3.3V
C
+
LTC1649
P
VCC2
P
VCC1
G1
I
FB
COMP
SS C
–
GND CP
OUT
1µF
10µF
MBR0530
0.1µF
C
C
0.01µF
R
C
7.5k
L
EXT
1.2µH
C1
220pF
10µF
MBR0530
R
IMAX
50k
22Ω 1k
Q3
IRF7801
Q1, Q2
IRF7801
TWO IN
PARALLEL
C
OUT
4400µF
C
IN
3300µF
SHDN
R2
12.7k
R1
12.4k
1649 TA03
+
0.33µF
+
+
+