LTC3875
41
3875fb
For more information
www.linear.com/LTC3875
TYPICAL APPLICATIONS
Figure
20.
Dual
Output
Ultralow
Ripple
2.5
V/2
A, 3.3
V/2
A
Step
-Down
Converter
V
O
5mV
/DIV
V
O
10mV
/DIV
2µs/DIV
3.1mV
V
IN
= 12V
V
OUT
= 2.5V
/2A
V
IN
= 25V
V
OUT
= 2.5V
/2A
3875 F20b
2µs/DIV
3875 F20c
3.8mV
TK/SS1
V
OSNS1
+
V
OSNS1
–
ITH1
ITH2
V
OSNS2
+
V
OSNS2
–
TK/SS2
SNSA2
+
SNS2
–
SGND/PGND
30
29
28
27
26
25
24
23
22
21
20
SW1
TG1
BOOST1
BG1
V
IN
INT
V
CC
EXT
V
CC
BG2
BOOST2
TG2
SW2
INT
V
CC
INT
V
CC
INT
V
CC
V
IN
1
2
3
4
5
6
7
8
9
10
41
SNSA1
+
SNS1
–
SNSD1
+
TCOMP1
TRSET1
TCOMP1
TRSET1
LTC3875
ILIM
RUN1
INT
V
CC
MODE/PLLIN
PHASMD
CLKOUT
SNSD2
+
11
12
13
14
15
16
17
18
19
C18 0.1
µF
D2
D1
CMDSH-3
R18, 2.2Ω
CMDSH-3
Q103 FDMS3610S
31
32
33
34
35
36
37
38
39
40
C11, 10pF
R19 174k
C12 220pF
V
O1SNS
+
V
O1SNS
–
TA
VG
TRSET2
TCOMP2
TA
VG
TRSET2
TCOMP2
TRSET1
TRSET2
TA
VG
FREQ
RUN2
IF
AST
ENTMPB
PGOOD
C21 0.1
µF
V
IN
C
IN5
10µF 1210
R32 100k 1%
C2 0.1
µF
C19, 1nF
1%
R13 63.4k
R14 20k
R10 1k
R9, 1k
C4 1nF
C3
470nF
C13 1µ
F
C14 4.7µF 10V
C7 0.1
µF
J3
J4
V
IN
12V TO 25V
V
IN
V
IN
GND
J1
J2
C
IN1
270µF 16V
+
R37, 10k
TCOMP1
THERMAL SENSOR
R40, 10k
R43, 5k
TCOMP2
THERMAL SENSOR
R39 50Ω
V
O2SNS
+
V
O2SNS
–
R21 90.9k
R25 20k
C17 68pF
C8
220pF
R15 174k 1%
C9 10pF
C15 68pF
R38 50Ω
11
µH
DCR = 15.8mΩ
C
OUT8
100µF 6.3V 1210
C
OUT5
330µF 2.5V 7343
R35 402Ω 1%
R34 10Ω 1%
+
RS2
0.006Ω
L2
C16 470nF
Q102
FDMS3610S
V
IN
C
IN2
10µF 1210
11
µH
DCR = 15.8mΩ
C
OUT1
100µF 6.3V 1210
C
OUT2
330µF 2.5V 7343
V
OUT1
R12 402Ω 1%
R17 10Ω 1%
+
RS1
0.006Ω
R20, 10Ω
R16, 10Ω
V
OUT2
R24, 10Ω
V
O2SNS
–
V
O2SNS
+
V
O1SNS
–
V
O1SNS
+
L1
V
OUT1
2.5V/2A
GND
R36, 10Ω
3875 F20a
J5
J6
V
OUT2
3.3V/2A
GND
