DC1441A - Schematic

1
2
3
4
5
6
7
8
REVISION HISTORY
VIN
JP1
4
C38
R28
OPT
OPT
1
CLKOUT
E15
4
DESCRIPTION
3
DATE
Circuit change, added parts
08/21/09
MS
E5
JP4
R10
VIN+
A
J1
0
VIN
40.2K
VIN
R29
100
R30
100
CLKOUT
R7
100K
1%
Q1
RJK0305DPB
5
6
7
8
C14
SW1
1nF
5
6
7
8
S1+
S1-
R3
4.5V - 14V
+
J2
2
R27
OPT
CIN2
CIN4
10uF
OPT
Q5
OPT
GND
E6
VIN-
R56
OPT
S1+
C37
CIN1
270uF
16V
1
VIN
E9
APPROVED
3
PLLIN
PHASMD
120 90 60
DEG DEG DEG
INTVCC
RUN1
JP3
2
A
1
ITEMP1
OPT
REV
3
R68
20.0K
E1
RUN1
1
ON 2
OFF 3
2
INTVCC
MODE
PS BM FCM
ITEMP2
R26
ECO
NOTE 1,
TO IMPLEMENT DCR SENSING ON PHASE 1, SHORT RS1.
REMOVE R29 AND R30. STUFF R58 WITH A 0 OHM RESISTOR.
THE DCR SENSE FILTER CONSISTS OF C14, R56 AND R57.
CALCULATE THESE VALUES PER THE DATA SHEET.
U1
1nF
TRK/SS2
S2-
DIFFP
41
SGND
0.1uF
VIN
R38
RUN2
C49
R43
OPT
20.0K
R11
1
2
3
1
2
3
31
32
SW1
CLKOUT
VIN
26
INTVCC
25
EXTVCC
24
BG2
23
PGND2
22
BOOST2
21
VIN
GND
C17
1uF
1
C11
4.7uF
10V
Q3
RJK0305DPB
BG2
D2
CIN3
CIN5
10uF
OPT
INTVCC
0
R59
CMDSH-3
4
C21
OPT
NOTE 4,
ONLY APPLY LOAD FROM J3 TO J4 FOR VOUT1
ONLY APPLY LOAD FROM J5 TO J6 FOR VOUT2
DO NOT CONNECT SCOPE GROUND TO E14
Q7
OPT
4
R60
0.1uF
OPT
L2
RS2
R39
100
INTVCC
R63
OPT
OPT
4
R70
0.002
R62
OPT
Q4
RJK0330DPB
0
C
0.4uH
D3
Q8
OPT
OPT
4
1
2
3
OPT
OPT
1
R61
VOUT2
COUT4
100uF
6.3V
2010
COUT5 COUT6
+ 330uF + 330uF
2.5V
2.5V
VOUT2
1.2V / 17A
C36
10uF
10V
J6
GND
S2-
R40
100
R12
J5
L2-
ILIM2
R69
B
EXTVCC
2
OPT
J4
VIN
5
6
7
8
OPT
VOUT1
1.8V / 17A
C32
10uF
10V
VO1-
INTVCC
TG2
RUN2
R41
+ COUT3
330uF
2.5V
E12
SW2
C48
+ COUT2
330uF
2.5V
2.2
R25
0
2010
R58
OPT
Q2
RJK0330DPB
R18
COUT1
100uF
6.3V
S1-
5
6
7
8
BG1
D4
OPT
4
J3
VOUT1
0.002
2
27
4
0.4uH
5
6
7
8
BG1
INTVCC
CMDSH-3
1
2
3
PGND1
0
1
2
3
33
PHSASMD
34
MODE/PLLIN
36
37
38
39
35
FREQ
R9
28
1
2
3
JP2
29
Q6
OPT
OPT
1
2
3
BOOST1
D1
5
6
7
8
ON
OFF
DIFFN
C47
OPT
11
R37
10
TG1
S2+
SENSE2-
30
5
6
7
8
9
C15
5.49K 1%
0
SENSE2+
L1TG1
1
2
3
TK/SS2
8
VO1+
OPT
RS1
5
6
7
8
7
TRK/SS2
S2+
E11
R57
1
2
3
ITH2
4
L1
TG2
6
SW2
OPT
R36
ITH2
R35
1.5nF
E10
VFB2
4
0.1uF
20
C44
R34
5
NC
20.0K
VOUT1
VFB2
19
150pF
PGOOD2
C43
18
R33
PGOOD1
SGND
17
VFB1
4
20.0K
B
16
ITH1
3
ITEMP2
2
VFB1
ILIM2
ITH1
15
R32
ITEMP1
TK/SS1
ILIM1
1
14
TRK/SS1
150pF
RUN1
SENSE1-
C42
R31
18.2K
1%
RUN2
1nF
0.1uF
13
C41
40
C2
SENSE1+
R2
OPT
DIFFOUT
0
C20
LTC3855EUJ
12
TRK/SS1
C
EXTVCC
R64
10
E3
R65
10
EXTVCC
EXTVCC
E14
C50
VO2_SNSVO2_SNS+
1uF
E2
INTVCC
GND
INTVCC
R42
E13
ILIM1
INTVCC
OPT
R46
100K
1%
E4
NOTE 2,
TO IMPLEMENT DCR SENSING ON PHASE 2, SHORT RS2.
REMOVE R39 AND R40. STUFF R62 WITH A 0 OHM RESISTOR.
THE DCR SENSE FILTER CONSISTS OF C15, R59 AND R60.
CALCULATE THESE VALUES PER THE DATA SHEET.
R44
OPT
R66
100K
1%
PGOOD1
PGOOD1
E16
NOTE 3,
FOR VOUT2 >= 3.3V, REMOVE R11 AND R70. STUFF R12
AND R69 WITH 0 OHM RESISTORS.
PGOOD2
PGOOD2
TEMPERATURE COMPENSATION NETWORK FOR DCR SENSING
ITEMP1
VFB1 R50
VFB2
ILIM1
OPT
Tooling Holes
R52
TRK/SS1
on PCB
R71
RN1
ILIM2
R67
ITEMP1
OPT
OPT
RN3
RN2
R47
OPT
TRK/SS2
C52
2
OPT
C51
2
OPT
RUN2
OPT
OPT
ITEMP2
LINEAR TECHNOLOGY HASMADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENTSUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
R53
OPT
OPT
OPT
OPT
1
Represents
RUN1 R55
CUSTOMER NOTICE
OPT
1
X2
ITH2
R51
OPT
2
R49
ITH1
1
R45
OPTIONAL JUMPERS FOR
SINGLE OUTPUT/DUAL PHASE
OPERATION
X1
1
1
D
ITEMP2
OPT
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USEWITH LINEAR TECHNOLOGY PARTS.
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CONTRACT NO.
APPROVALS
PCB DES.
ENG.
MI
MS
TECHNOLOGY
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900
Fax: (408)434-0507
LTC Confidential-For Customer Use Only
TITLE: SCHEMATIC
DUAL OUTPUT SYNCHRONOUS BUCK CONVERTER
SIZE
IC NO.
REV
LTC3855EUJ
3
DEMO CIRCUIT 1441A
DATE: Friday, November 20, 2009
7
SHEET
8
1 OF 1
D
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