DEMO MANUAL DC1617A
LTC3855EFE
Dual Output Synchronous
Buck Converter
DESCRIPTION
Demonstration circuit DC1617A is a dual output synchronous buck converter featuring the LTC®3855EFE in a high
density, two sided drop-in layout with power components
on the top and the control circuit on the bottom. The package style for the LTC3855EFE is a 38-lead TSSOP.
The board comes in two assembly types. The –A assembly
provides 2.5V/15A and 1.8V/15A from a 4.5V to 26V input.
DCR inductor sensing is used to provide the highest efficiency. The current limit is NTC compensated to provide
the minimal amount of variation over temperature. The –B
assembly is a high power, 12V/6A and 5V/10A converter
with a 13V to 36V input. A sense resistor is used to provide
a precise current limit.
The main features of the board are listed below:
• Optional resistors for single output dual phase operation.
• PLLIN pin for synchronization to an external clock
which can be used in conjunction with PHASMD pin
and CLKOUT pin for up to 12-phase operation.
• Selectable light load operating modes of pulse skip,
Burst Mode® operation or FCM.
• TRACK/SS pins for external rail tracking.
• RUN pins and PGOOD pins for each phase.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
• Remote sensing for VOUT2 on the –A assembly. On the
–B assembly, the diffamp is bypassed since VOUT2 is >
3.3V.
PERFORMANCE SUMMARY
(TA = 25°C)
–A Assembly
PARAMETER
CONDITIONS
Minimum Input Voltage
VALUE
4.5V
Maximum Input Voltage
26V
Output Voltage VOUT1
IOUT1 = 0A TO 15A, VIN = 4.5V to 26V
Output Voltage VOUT2
IOUT2 = 0A TO 15A, VIN = 4.5V to 26V
1.8V ±2%
VOUT1 Maximum Output Current, IOUT1
VIN = 4.5V to 26V, VOUT1 = 2.5V
15A
VOUT2 Maximum Output Current, IOUT2
VIN = 4.5V to 26V, VOUT2 = 1.8V
15A
Nominal Switching Frequency
Efficiency, See Figure 3
2.5V ±2%
250kHz
VOUT1 = 2.5V, IOUT1 = 15A, VIN = 12V
93.0% Typical
VOUT2 = 1.8V, IOUT2 = 15A, VIN = 12V
91.7% Typical
dc1617af
1
DEMO MANUAL DC1617A
PERFORMANCE SUMMARY
(TA = 25°C)
–B Assembly
PARAMETER
CONDITIONS
VALUE
Minimum Input Voltage
13V
Maximum Input Voltage
36V
Output Voltage VOUT1
IOUT1 = 0A TO 6A, VIN = 13V to 36V
Output Voltage VOUT2
IOUT2 = 0A TO 10A, VIN = 13V to 36V
5V ±3%
VOUT1 Maximum Output Current, IOUT1
VIN = 13V to 36V, VOUT1 = 12V
6A
VOUT2 Maximum Output Current, IOUT2
VIN = 13V to 36V, VOUT2 = 5V
Nominal Switching Frequency
Efficiency, See Figure 4
12V ±3%
10A
250kHz
VOUT1 = 12V, IOUT1 = 6A, VIN = 24V
97.1% Typical
VOUT2 = 5V, IOUT2 = 10A, VIN = 24V
94.1% Typical
QUICK START PROCEDURE
Demonstration circuit 1617A is easy to set up to evaluate
the performance of the LTC3855EFE. Please refer to Figure 1
for proper measurement equipment setup and follow the
procedure below.
1) With power off, connect the input supply, load and
meters as shown in Figure 1. Preset the load to 0A
and VIN supply to be 0V. Place jumpers in the following
positions:
JP1
RUN1
ON
JP2
RUN2
ON
JP3
MODE
FCM
2) Set the input voltage to within the nominal input voltage
range and check for the proper output voltage with no
load and then full load. See below:
–A assembly
VIN = 4.5V to 26V
VOUT1 = 2.5V/15A, VOUT2 = 1.8V/15A
3) Once the DC regulation is confirmed, observe the output
voltage ripple, load step response, efficiency and other
parameters.
Note 1. Do not apply load between the VO1+ and VO1– pins
or between the VO2_SNS+ and VO2_SNS– pins. These
pins are only intended to Kelvin sense the output voltage
across COUT1 and COUT4. Heavy load currents applied
across the VO1± sense pins will damage these sense
traces. Heavy load currents across the VO2_SNS± pins
will damage the converter.
Note 2. When measuring the output or input voltage ripple,
do not use the long ground lead on the oscilloscope probe.
See Figure 2 for the proper scope probe technique. Short,
stiff leads need to be soldered to the (+) and (–) terminals
of an output capacitor. The probe’s ground ring needs to
touch the (–) lead and the probe tip needs to touch the
(+) lead.
–B assembly
VIN = 13V to 36V
VOUT1 = 12V/6A, VOUT2 = 5V/10A
dc1617af
2
DEMO MANUAL DC1617A
QUICK START PROCEDURE
DC1617a F01
Figure 1. Proper Measurement Equipment Setup.
+
VOUT
COUT
–
GND
DC1617a F02
Figure 2. Measuring Output Voltage Ripple
dc1617af
3
DEMO MANUAL DC1617A
QUICK START PROCEDURE
95
2.5V
1.8V
EFFICIENCY (%)
90
VIN =12V, FSW = 250kHz, MODE = FCM
85
BOTH PHASES:
QT = RENESAS RJK0305DPB
QB = RENESAS RJK0330DPB
L = WÜRTH 744355090
(0.9μH, DCR = 1.6mΩ ±10%)
DCR SENSING IMPLEMENTED
80
75
0
2
4
6
8
10
LOAD CURRENT (A)
12
14
16
DN1617a F03
Figure 3. Typical Efficiency Curves of the –A Assembly
100
VIN =24V, FSW = 250kHz, MODE = FCM
12V
EFFICIENCY (%)
95
5V
90
BOTH PHASES:
QT = INFINEON BSC093N04LS G
QB = INFINEON BSC093N04LS G
85
12V L = WÜRTH 7443551131
(13.1μH, DCR = 11.2mΩ ±10%)
12V RSENSE = 8mΩ
15V L = WÜRTH 7443551370
(3.7μH, DCR = 4.9mΩ ±10%)
5V RSENSE = 5mΩ
80
0
2
4
6
LOAD CURRENT (A)
8
10
12
DN1617a F04
Figure 4. Typical Efficiency Curves of the –B Assembly
dc1617af
4
DEMO MANUAL DC1617A
ITEMP1
ITEMP2
R45
18.2k
1%
R51
18.2k
1%
2
RN1
100k
1
R47
45.3k
1%
2
RN2
100k
R53
45.3k
1%
1
DN1617a F05
Figure 5. Temperature Compensation Network for DCR Sensing, As Used on the –A Assembly
35
2.5V NO TEMPERATURE COMPENSATION
1.8V NO TEMPERATURE COMPENSATION
2.5V WITH TEMPERATURE COMPENSATION
1.8V WITH TEMPERATURE COMPENSATION
CURRENT LIMIT (A)
30
25
20
IOUT(MAX)
15
10
–60
–40
–20
0
20
40
60
INDUCTOR TEMPERATURE (°C)
80
100
120
DN1617a F06
Figure 6. Current Limit vs Inductor Temperature for the –A Assembly
dc1617af
5
DEMO MANUAL DC1617A
SINGLE OUTPUT/DUAL PHASE OPERATION
A single output/dual phase converter may be preferred for
high output current applications. The benefits of single
output/dual phase operation is lower ripple current through
the input and output capacitors, faster load step response
and simplified thermal design. To implement single output/
dual phase operation, make the following modifications:
• Tie VOUT1 to VOUT2 by tying together the exposed copper
pads on the VOUT shapes with pieces of heavy copper
foil.
• Tie ITH1 to ITH2 by stuffing 0Ω at R49.
• Tie TRK/SS1 to TRK/SS2 by stuffing 0Ω at R52.
• Tie RUN1 to RUN2 by stuffing 0Ω at R55.
• Keep the ILIM pins at the same potential or tie them
together by stuffing 0Ω at R71.
• Keep the ITEMP pins at the same potential or tie them
together by stuffing 0Ω at R67.
• Remove the redundant ITH compensation network, VFB
divider and TRACK/SS cap.
• Recompensate if necessary.
• Tie VFB1 to VFB2 by stuffing 0Ω at R50.
TEMPERATURE COMPENSATION NETWORK FOR DCR SENSING
As the temperature of an inductor increases, its DCR goes
up due to the positive temperature coefficient of the copper
winding. The NTC temperature compensation network on
the ITEMP pins of the –A assembly (see Figure 5) allows
VSENSE(maximum) of the LTC3855 to track the DCR of
the inductor which provides a much smaller variation of
the current limit over temperature. The temperature of
inductors L1 and L2 are sensed with the NTC thermistors at RN1 and RN2. R45, R47, R51 and R53 are used
for linearization.
Figure 6 shows the current limit of the –A assembly versus
inductor temperature with and without the temperature
compensation network stuffed. As can be seen, the temperature compensation network greatly reduces the drop
in the current limit over temperature and allows the current
limit to be more accurate.
dc1617af
6
DEMO MANUAL DC1617A
PARTS LIST
–A Assembly (2.5V and 1.8V Converter)
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
CAP 0805 4.7μF 10% 10V X5R
AVX 0805ZD475KAT2A
Required Circuit Components
1
1
C11
2
2
C14, C15
CAP 0603 0.22μF 10% 25V X7R
AVX 06033C224KAT2A
3
1
C17
CAP 0603 0.1μF 10% 50V X7R
AVX 06035C104KAT2A
4
4
C2, C20, C21, C47
CAP 0603 0.1μF 10% 25V X7R
AVX 06033C104KAT2A
5
2
C37, C49
CAP 0603 22pF 5% 50V NPO
AVX 06035A220JAT2A
6
1
C41
CAP 0603 1nF 10% 50V X7R
AVX 06035C102KAT2A
7
1
C42
CAP 0603 220pF 5% 25V NPO
AVX 06033A221JAT2A
8
1
C43
CAP 0603 330pF 5% 25V NPO
AVX 06035A331JAT2A
9
1
C44
CAP 0603 3.3nF 10% 50V X7R
AVX 06035C332KAT2A
10
1
CIN1
CAP 220μF 20% 50V ALUM ELEC
PANASONIC EEEFK1H221P
11
6
CIN3 TO CIN8
CAP 1210 4.7μF 10% 50V X7R
MURATA GRM32ER71H475KA88L
12
4
COUT1, COUT2, COUT4, COUT5
CAP 7343 330μF 20% 4V POLYMER TANT
KEMET T520V337M004ATE009
13
2
COUT3, COUT6
CAP 1210 100μF 20% 6.3V X5R
TDK C3225X5R0J107M
14
2
D1, D2
DIODE SCHOTTKY 1A 100V PWRDI123
DIODES INC DFLS1100-7
15
2
L1, L2
INDUCTOR 0.9μH
WÜRTH 744355090
16
2
Q1, Q3
MOSFET POWER N-CH LFPAK
RENESAS RJK0305DPB
17
2
Q2, Q4
MOSFET POWER N-CH LFPAK
RENESAS RJK0330DPB
18
12
R3, R7, R9, R10, R11, R44, R25,
R36, R58, R62, R63, R70
RES 0603 0Ω JUMPER
VISHAY CRCW06030000Z0EA
19
1
R18
RES 0603 2.2Ω 5% 1/10W
VISHAY CRCW06032R20JNEA
20
1
R27
RES 0603 63.4k 1% 1/10W
VISHAY CRCW060363K4FKEA
21
4
R31, R32, R33, R68
RES 0603 20k 1% 1/10W
VISHAY CRCW060320K0FKEA
22
1
R35
RES 0603 11.8k 1% 1/10W
VISHAY CRCW060311K8FKEA
23
1
R43
RES 0603 40.2k 1% 1/10W
VISHAY CRCW060340K2FKEA
24
2
R45, R51
RES 0603 18.2k 1% 1/10W
VISHAY CRCW060318K2FKEA
25
2
R46, R66
RES 0603 100k 1% 1/10W
VISHAY CRCW0603100KFKEA
26
2
R47, R53
RES 0603 45.3k 1/10W
VISHAY CRCW060345K3FKEA
27
2
R56, R59
RES 0603 3.09k 1% 1/10W
VISHAY CRCW06033K09FKEA
28
1
R57
RES 0603 8.45k 1% 1/10W
VISHAY CRCW06038K45FKEA
29
1
R60
RES 0603 11k 1% 1/10W
VISHAY CRCW060311K0FKEA
30
2
R64, R65
RES 0603 10Ω 5% 1/10W
VISHAY CRCW060310R0JNEA
31
2
RN1, RN2
THERMISTOR 0603 100k 5%
MURATA NCP18WF104J03RB
32
2
RS1, RS2
RES 2010 0 OmΩ 1% 1/2W
TEPRO RN6083
33
1
U1
IC DUAL OUTPUT BUCK CONTROLLER
LINEAR TECHNOLOGY LTC3855EFE#PBF
dc1617af
7
DEMO MANUAL DC1617A
PARTS LIST
–A Assembly (2.5V and 1.8V Converter)
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Additional Circuit Components
1
0
C38, C48, C51, C52
CAP 0603
OPTION
2
1
C50
CAP 0603 1μF 10% 16V X5R
AVX 0603YD105KAT
3
0
CIN2
CAP ALUM ELEC - PANASONIC SIZE G
OPTION
4
0
CIN9 TO CIN11
CAP 1210
OPTION
5
0
Q5 TO Q8
MOSFET POWER LFPAK
OPTION
6
0
R2, R12, R26, R28 TO R30, R34, RES 0603
R37 TO R42, R49, R50, R52, R55,
R61, R67, R69, R71 TO R73
OPTION
7
0
RN3
OPTION
1
14
E1 TO E6, E9, E10 TO E16
TESTPOINT TURRET 0.094" PbF
MILL-MAX 2501-2-00-80-00-00-07-0
2
6
J1, J2, J3, J4, J5, J6
JACK BANANA
KEYSTONE 575-4
3
2
JP1, JP2
HEADER 3-PIN 0.079 SINGLE ROW
SAMTEC TMM-103-02-L-S
4
4
JP1 TO JP4
SHUNT 0.079" CENTER
SAMTEC 2SN-BK-G
5
2
JP3, JP4
HEADER 4-PIN 0.079 SINGLE ROW
SAMTEC TMM-104-02-L-S
THERMISTOR 0603
Hardware
dc1617af
8
DEMO MANUAL DC1617A
PARTS LIST
–B Assembly (12V and 5V Converter)
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Required Circuit Components
1
1
C11
CAP 0805 4.7μF 10% 10V X5R
AVX 0805ZD475KAT2A
2
2
C14, C15
CAP 0603 1nF 10% 50V X7R
AVX 06035C102KAT
3
5
C2, C17, C20, C21, C47
CAP 0603 0.1μF 10% 50V X7R
AVX 06035C104KAT2A
4
1
C41
CAP 0603 3.3nF 10% 50V X7R
AVX 06035C332KAT2A
5
2
C42, C43
CAP 0603 47pF 5% 25V NPO
AVX 06033A470JAT2A
6
1
C44
CAP 0603 1.5nF 10% 50V X7R
AVX 06035C152KAT2A
7
1
CIN1
CAP 220μF 20% 50V ALUM ELEC
PANASONIC EEEFK1H221P
8
6
CIN3 TO CIN8
CAP 1210 4.7μF 10% 50V X7R
MURATA GRM32ER71H475KA88L
9
1
COUT1
CAP 7343 68μF 20% 16V POLYMER TANT
KEMET T520D686M016ATE050
10
2
COUT3, COUT6
CAP 1210 10μF 10% 25V X5R
KEMET C1210C106K3PAC7533
11
1
COUT4
CAP 7343 220μF 20% 6V POLYMER TANT
KEMET T520V227M006ATE012
12
2
D1, D2
DIODE SCHOTTKY 1A 100V PWRDI123
DIODES INC DFLS1100-7
13
1
L1
INDUCTOR 13μH
WÜRTH 7443551131
14
1
L2
INDUCTOR 3.7μH
WÜRTH 7443551370
15
4
Q1, Q2, Q3, Q4
MOSFET POWER N-CH LFPAK
INFINEON BSC093N04LS G
16
13
R3, R7, R9, R10, R12, R25, R36, R42,
R61, R64, R65, R69, R73
RES 0603 0Ω JUMPER
VISHAY CRCW06030000Z0EA
17
1
R18
RES 0603 2.2Ω 5% 1/10W
VISHAY CRCW06032R20JNEA
18
1
R27
RES 0603 383k 1% 1/10W
VISHAY CRCW0603383KFKEA
19
4
R29, R30, R39, R40
RES 0603 10Ω 5% 1/10W
VISHAY CRCW060310R0JNEA
20
2
R31, R35
RES 0603 15k 1% 1/10W
VISHAY CRCW060315K0FKEA
21
3
R32, R33, R68
RES 0603 20k 1% 1/10W
VISHAY CRCW060320K0FKEA
22
1
R43
RES 0603 147k 1% 1/10W
VISHAY CRCW0603147KFKEA
23
2
R46, R66
RES 0603 100k 1% 1/10W
VISHAY CRCW0603100KFKEA
24
1
RS1
RES 2010 0.008Ω 1% 1/2W
VISHAY WSL20108L00FEA
25
1
RS2
RES 2010 0.005Ω 1% 1/2W
VISHAY WSL20105L00FEA
26
1
U1
IC DUAL OUTPUT BUCK CONTROLLER
LINEAR TECHNOLOGY LTC3855EFE#PBF
Additional Circuit Components
1
0
C37, C38, C48, C49, C51, C52
CAP 0603
OPTION
2
1
C50
CAP 0603 1μF 10% 16V X5R
AVX 0603YD105KAT
3
0
CIN2
CAP ALUM ELEC - PANASONIC SIZE G
OPTION
4
0
CIN9 TO CIN11
CAP 1210
OPTION
5
0
COUT2, COUT5
CAP 7343
OPTION
6
0
Q5 TO Q8
MOSFET POWER LFPAK
OPTION
7
0
R2, R11, R26, R28, R34, R37, R38, R41,
R44, R45, R47, R49 TO R53
RES 0603
OPTION
8
0
RN1 TO RN3
THERMISTOR 0603
OPTION
1
14
E1 TO E6, E9, E10, E16
TESTPOINT TURRET 0.094" PbF
MILL-MAX 2501-2-00-80-00-00-07-0
2
6
J1, J2, J3, J4, J5, J6
JACK BANANA
KEYSTONE 575-4
3
2
JP1, JP2
HEADER 3-PIN 0.079 SINGLE ROW
SAMTEC TMM-103-02-L-S
4
4
JP1 TO JP4
SHUNT .0079" CENTER
SAMTEC 2SN-BK-G
5
2
JP3, JP4
HEADER 4-PIN 0.079 SINGLE ROW
SAMTEC TMM-104-02--L-S
Hardware
dc1617af
9
D
C
B
A
E16
E4
E2
E3
E10
TRK/SS1
VFB1
0
3
1
2
OPT
1uF
C50
R73
R72
JP2
3
1
2
R55
1
OPT
TRK/SS2
ITEMP1
R67
OPT
R71
R52
ILIM1
RUN1
OPT
ITEMP2
ILIM2
RUN2
R46
100K
1%
R66
100K
1%
INTVCC
VOUT2
INTVCC
OPT
R50
OPT
VFB2
OPT
VOUT1
R33
RUN2
OPT
OPT
R38
R41
OPT
ITH2
R32
3.3nF
C48
VIN
11.8K 1%
C44
220pF
R35
OPT
R49
C42
330pF
1nF
C43
OPT
0.1uF
C47
OPT
R34
R31
20K
1%
0.1uF
C41
R28
OPT
C2
4
2
100K
RN1
S2-
S2+
INTVCC
R40
OPT
S1+
S1-
R29
OPT
R42
R39
OPT
OPT
0
R70
R69
R44
0
ILIM1
OPT
0.22uF
C14
R30
OPT
C15 0.22uF
TRK/SS2
ITH2
VFB2
VFB1
ITH1
R43
40.2K
1%
0
0
TRK/SS1
R27
63.4K
1%
R10
ITEMP1
ITEMP2
R63
0
R61
ILIM2
ILIM1
RUN2
OPT
DIFFOUT
DIFFN
DIFFP
SENSE2-
SENSE2+
TK/SS2
ITH2
VFB2
VFB1
ITH1
TRK/SS1
SENSE1-
SENSE1+
RUN1
ITEMP1
ITEMP2
ILIM2
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
18.2K
1%
R45
45.3K
1%
R47
OPT
C51
OPT
RN3
3
100K
RN2
ITEMP2
18.2K
1%
R51
FREQ
45.3K
1%
R53
OPT
C52
INTVCC
PGOOD1
PGOOD2
SW2
TG2
BOOST2
PGND2
BG2
EXTVCC
INTVCC
VIN
BG1
PGND1
BOOST1
TG1
SW1
CLKOUT
PHSASMD
MODE/PLLIN
LTC3855EFE
U1
1
INTVCC
4
2
4
20
21
22
23
24
25
26
27
28
29
30
31
4
SW2
TG2
BG2
BG1
TG1
R9
33
C21
0.1uF
0
R25
SW1
0
C17
0.1uF
50V
2.2
R18
DFLS1100-7
D2
5
INTVCC
5
4
4
Q3
RJK0305DPB
Q2
RJK0330DPB
4
4
Q4
RJK0330DPB
INTVCC
VIN
INTVCC
4
Q1
RJK0305DPB
DFLS1100-7
D1
0.1uF
C20
C11
4.7uF
10V
E15
CLKOUT
CLKOUT
JP4
EXTVCC
3
32
34
35
36
37
38
R7
0
Fsw = 250kHz (typ)
TEMPERATURE COMPENSATION NETWORK FOR DCR SENSING
R11
ITEMP1
R12
OPT
22pF
C49
20K 1%
20K 1%
22pF
JP3
C37
RUN1
2
OPT
1
3
R26
C38
VIN
OPTIONAL JUMPERS FOR
SINGLE OUTPUT/DUAL PHASE
OPERATION
PGOOD2
PGOOD1
EXTVCC
EXTVCC
OPT
R37
0
OPT
R2
JP1
R3
R36
VOUT1
E9
ITH1
PGOOD1
PGOOD2
GND
EXTVCC
TRK/SS2
TRK/SS1
PLLIN
E1
R68
20.0K
2
1
4
4
Q6
OPT
Q5
OPT
R59
CIN8
4.7uF
50V
1210
R56
CIN9
OPT
1210
3.09K
R58
0
0.9uH
L2
1%
3.09K
R62
0
CIN11
OPT
1210
0.9uH
L1
1%
&86720(5127,&(
Q8
OPT
Q7
OPT
VIN
CIN6
4.7uF
50V
1210
6
L2-
R60
11.0K
1%
L1-
R57
8.45K
1%
CIN7
4.7uF
50V
1210
6
7+,6&,5&8,7,635235,(7$5<72/,1($57(&+12/2*<$1'
6833/,(')2586(:,7+/,1($57(&+12/2*<3$576
/,1($57(&+12/2*<+$60$'($%(67())25772'(6,*1$
&,5&8,77+$70((76&86720(56833/,('63(&,),&$7,216
+2:(9(5,75(0$,167+(&86720(5
65(63216,%,/,7<72
9(5,)<3523(5$1'5(/,$%/(23(5$7,21,17+($&78$/
$33/,&$7,21&20321(1768%67,787,21$1'35,17('
&,5&8,7%2$5'/$<2870$<6,*1,),&$17/<$))(&7&,5&8,7
3(5)250$1&(255(/,$%,/,7<&217$&7/,1($5
7(&+12/2*<$33/,&$7,216(1*,1((5,1*)25$66,67$1&(
4
VIN
5
6
7
8
INTVCC
2
1
1
2
3
3
SGND
39
5
6
7
8
5
6
7
8
1
2
3
5
6
7
8
1
2
3
5
6
7
8
1
2
3
1
2
3
5
6
7
8
1
2
3
5
6
7
8
1
2
3
5
6
7
8
S1+
S2+
2
2
1
S1S2-
CIN5
4.7uF
50V
1210
7
COUT3
100uF
1210
CIN4
4.7uF
50V
1210
2
REV
+ COUT1
330uF
4V
7343
0,.(6
$33(1*
6&$/( 121(
0,
3&%'(6
R65
10
7
VO2_SNSVO2_SNS+
GND
VOUT2
VO1-
GND
VOUT1
VO1+
8
LTC3855EFE
6+((7 DEMO CIRCUIT 1617A-A
2) 5(9
0F&DUWK\%OYG
0LOSLWDV&$
3KRQH ZZZOLQHDUFRP
)D[
/7&&RQILGHQWLDO)RU&XVWRPHU8VH2QO\
E13
E14
J6
J5
E12
J4
J3
E11
VIN-
GND
VIN
VIN+
DUAL OUTPUT SYNCHRONOUS
BUCK CONVERTER
,&12
'$7( Monday, June 20, 2011
1$
6,=(
VOUT2
COUT4
330uF
4V
7343
TECHNOLOGY
COUT5
+ 330uF
4V
7343
7,7/( 6&+(0$7,&
R64
10
COUT6
100uF
1210
+
3. ALL CAPCITORS AND RESISTORS ARE IN 0603.
2. ONLY APPLY LOAD FROM J5 TO J6 FOR VOUT2
4. INSTALL SHUNTS AS SHOWN.
J2
E6
1. ONLY APPLY LOAD FROM J3 TO J4 FOR VOUT1
$33529$/6
0
2010
RS2
VOUT1
+ CIN1
220uF
50V
J1
E5
MIKE S.
+ CIN2
OPT
+ COUT2
330uF
4V
7343
CIN3
4.7uF
50V
1210
VIN
DATE
06/20/11
APPROVED
8
PRODUCTION
REVISION HISTORY
DESCRIPTION
NOTES: UNLESS OTHERWISE SPECIFIED,
0
2010
RS1
CIN10
OPT
1210
ECO
1
2
1
2
10
1
2
3
1
D
C
B
A
DEMO MANUAL DC1617A
SCHEMATIC DIAGRAM
dc1617af
D
C
B
A
E16
E4
E2
E3
E10
VFB1
TRK/SS1
0
3
1
2
OPT
1uF
R73
R72
JP2
3
1
2
0
1
OPT
TRK/SS2
ILIM1
ITEMP1
R67
OPT
R71
R52
OPT
VFB2
R55
R50
RUN1
OPT
ITH2
ILIM2
OPT
ITEMP2
R66
100K
1%
INTVCC
RUN2
R46
100K
1%
INTVCC
VOUT2
OPT
R49
OPT
RUN2
OPT
VOUT1
R33
1.5nF
R41
OPT
R38
1%
C48
VIN
15K
R35
47pF
47pF
C42
3.3nF
C43
OPT
0.1uF
C47
OPT
R34
R31
15K
1%
0.1uF
C41
R28
C50
C44
R32
4
2
100K
RN1
OPT
R43
147K
1%
S2-
S1+
S1-
R29
10
INTVCC
R42
R39
10
1nF
0
OPT
R70
R44
OPT
ILIM1
0
C14
R30
10
R69
C15 1nF
TRK/SS2
ITH2
VFB2
VFB1
ITH1
S2+
R40
10
0
TRK/SS1
R27
383K
1%
R10
ITEMP1
ITEMP2
R63
OPT
R61
ILIM2
ILIM1
RUN2
0
DIFFOUT
DIFFN
DIFFP
SENSE2-
SENSE2+
TK/SS2
ITH2
VFB2
VFB1
ITH1
TRK/SS1
SENSE1-
SENSE1+
RUN1
ITEMP1
ITEMP2
ILIM2
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
OPT
R45
OPT
R47
OPT
C51
OPT
RN3
3
100K
RN2
ITEMP2
OPT
R51
FREQ
OPT
R53
OPT
C52
INTVCC
PGOOD1
PGOOD2
SW2
TG2
BOOST2
PGND2
BG2
EXTVCC
INTVCC
VIN
BG1
PGND1
BOOST1
TG1
SW1
CLKOUT
PHSASMD
MODE/PLLIN
LTC3855EFE
U1
1
INTVCC
4
2
4
20
21
22
23
24
25
26
27
28
29
30
4
C21
0.1uF
0
R25
SW2
TG2
BG2
BG1
R9
32
31
TG1
SW1
0
C17
0.1uF
50V
2.2
R18
DFLS1100-7
D2
5
INTVCC
5
4
4
Q3
BSC093N04LS
Q2
BSC093N04LS
4
4
Q4
BSC093N04LS
INTVCC
VIN
INTVCC
4
Q1
BSC093N04LS
DFLS1100-7
D1
0.1uF
C20
C11
4.7uF
10V
E15
CLKOUT
CLKOUT
JP4
EXTVCC
3
33
34
35
36
37
38
R7
0
Fsw = 250kHz (typ)
TEMPERATURE COMPENSATION NETWORK FOR DCR SENSING
R11
ITEMP1
R12
0
OPT
C49
20K 1%
20K 1%
OPT
JP3
C37
OPT
C2
2
OPT
RUN1
1
3
R26
C38
VIN
OPTIONAL JUMPERS FOR
SINGLE OUTPUT/DUAL PHASE
OPERATION
PGOOD2
PGOOD1
EXTVCC
EXTVCC
OPT
R37
0
OPT
R2
JP1
R3
R36
VOUT1
E9
ITH1
PGOOD1
PGOOD2
GND
EXTVCC
TRK/SS2
TRK/SS1
PLLIN
E1
R68
20.0K
2
1
4
4
Q6
OPT
Q5
OPT
R59
CIN8
4.7uF
50V
1210
R56
CIN9
OPT
1210
OPT
R58
OPT
3.7uH
L2
OPT
R62
OPT
CIN11
OPT
1210
13uH
L1
&86720(5127,&(
Q8
OPT
Q7
OPT
VIN
CIN6
4.7uF
50V
1210
6
L2-
R60
OPT
L1-
R57
OPT
CIN7
4.7uF
50V
1210
6
7+,6&,5&8,7,635235,(7$5<72/,1($57(&+12/2*<$1'
6833/,(')2586(:,7+/,1($57(&+12/2*<3$576
/,1($57(&+12/2*<+$60$'($%(67())25772'(6,*1$
&,5&8,77+$70((76&86720(56833/,('63(&,),&$7,216
+2:(9(5,75(0$,167+(&86720(5
65(63216,%,/,7<72
9(5,)<3523(5$1'5(/,$%/(23(5$7,21,17+($&78$/
$33/,&$7,21&20321(1768%67,787,21$1'35,17('
&,5&8,7%2$5'/$<2870$<6,*1,),&$17/<$))(&7&,5&8,7
3(5)250$1&(255(/,$%,/,7<&217$&7/,1($5
7(&+12/2*<$33/,&$7,216(1*,1((5,1*)25$66,67$1&(
4
VIN
5
6
7
8
INTVCC
2
1
1
2
3
3
SGND
39
5
6
7
8
5
6
7
8
1
2
3
5
6
7
8
1
2
3
5
6
7
8
1
2
3
1
2
3
5
6
7
8
1
2
3
5
6
7
8
1
2
3
5
6
7
8
1
2
3
S1+
S2+
CIN5
4.7uF
50V
1210
7
COUT3
10uF
1210
CIN4
4.7uF
50V
1210
2
REV
+ COUT1
68uF
16V
7343
J2
VO1-
GND
VOUT1
VO1+
VIN-
GND
VIN
VIN+
0,.(6
$33(1*
6&$/( 121(
0,
3&%'(6
R65
10
7
VOUT2
GND
VOUT2
VO2_SNSVO2_SNS+
J6
J5
,&12
8
LTC3855EFE
6+((7 DEMO CIRCUIT 1617A-B
DUAL OUTPUT SYNCHRONOUS
BUCK CONVERTER
2) 5(9
0F&DUWK\%OYG
0LOSLWDV&$
3KRQH ZZZOLQHDUFRP
)D[
/7&&RQILGHQWLDO)RU&XVWRPHU8VH2QO\
E13
E14
COUT4
220uF
6.3V
7343
'$7( Monday, June 20, 2011
1$
6,=(
+
TECHNOLOGY
COUT5
+ OPT
7,7/( 6&+(0$7,&
R64
10
COUT6
10uF
1210
4. INSTALL SHUNTS AS SHOWN.
3. ALL CAPCITORS AND RESISTORS VALUES ARE 0603.
2. ONLY APPLY LOAD FROM J5 TO J6 FOR VOUT2
E12
J4
J3
E11
E6
1. ONLY APPLY LOAD FROM J3 TO J4 FOR VOUT1
$33529$/6
0.005
2010
RS2
VOUT1
+ CIN1
220uF
50V
J1
E5
MIKE S.
+ CIN2
OPT
+ COUT2
OPT
CIN3
4.7uF
50V
1210
VIN
DATE
06/20/11
APPROVED
8
PRODUCTION
REVISION HISTORY
DESCRIPTION
NOTES: UNLESS OTHERWISE SPECIFIED,
0.008
2010
RS1
CIN10
OPT
1210
ECO
1
2
1
2
2
2
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
1
S1S2-
1
D
C
B
A
DEMO MANUAL DC1617A
SCHEMATIC DIAGRAM
dc1617af
11
DEMO MANUAL DC1617A
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions:
This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT
OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete
in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety
measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union
directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations.
If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 30 days from the date
of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU
OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS
FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR
ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES.
The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC from all claims
arising from the handling or use of the goods. Due to the open construction of the product, it is the user’s responsibility to take any and all
appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or
agency certified (FCC, UL, CE, etc.).
No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive.
Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and
observe good laboratory practice standards. Common sense is encouraged.
This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC application engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
dc1617af
12 Linear Technology Corporation
LT 0911 • PRINTED IN USA
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