Datasheet

LT3507A
25
3507af
TYPICAL APPLICATIONS
15V, 1.8V and 1.2V 2-Stage Step Down
V
IN1
BOOST1 UVLO
OVLO
PGOOD2
PGOOD3
BOOST 2
SW2
FB2
V
C2
BOOST3
SW3
FB3
TRK/SS2
TRK/SS3
PGOOD1
SW1
FB1
V
C1
TRK/SS1
BIAS
0.1µF
22µF
D1
68.1k
31.6k
220pF
0.01µF
169k
L1 10µH
V
OUT1
15V
0.4A
V
BST
3V
V
IN
21V TO 36V
L2 3.3µH
V
IN2
V
IN3
V
INSW
49.9k 3.4k
UVLO = 19V
11.5k
9.53k
10µF
DRIVE
FB4
TRK/SS4
RT/SYNC
V
C3
GND
LT3507A
RUN1
RUN2
RUN3
0.1µF
33µF
PGOOD
V
BST
D2
13.3k
SHDN
1000pF
D1: DIODES, INC. B140A
D2, D3: DIODES, INC. B240A
L1: TDK LTF5022T-100M1R4
L2: TDK VLCF5020T-3R3N2R0-1
L3: TDK VLCF5020T-2R2N1R7
Q1: DIODES INC. BC817-16
15k
100k
3507A TA04
54.9k
f
SW
= 800kHz
V
OUT2
1.8V
1.8A
18.7k
V
OUT2
L3 2.2µH
0.1µF
47µF
V
BST
D3
12.7k
1000pF
30.1k
270pF
2.2µF
Q1
V
OUT3
1.2V
1.8A
15.0k