1
dc1757bf
DEMO MANUAL DC1757B
Description
LTC3789EGN
High Efficiency
12V/12A Buck-Boost Converter
Demonstration circuit 1757B is a high efficiency syn-
chronous buck-boost DC/DC converter with a 6V to 36V
input voltage range. It can supply a 12A maximum load
current with a 12V output. The demo board features the
LT C
®
3789EGN controller. The constant frequency current
mode architecture allows a phase-lockable frequency of up
to 600kHz, while an optional output current feedback loop
provides support for applications such as battery charging.
With a wide input range, wide output range and seamless
transfers between operation modes, the LTC3789 is ideal
for automotive, telecom, distributed DC power systems
and battery-powered applications.
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.
performance summary
The light load operation mode of the converter is deter-
mined with the MODE/PLLIN pin. Use JP2 jumper to select
pulse-skipping mode or forced continuous mode (CCM)
operation. The switching frequency is pre-set at about
200kHz. The converter can also be externally synchronized
to an external clock through the MODE/PLLIN pin (PLLIN
terminal on the board). To shut down the converter, force
the RUN pin below 1.2V (JP1: OFF). The power good
output (PGOOD terminal) is low when the output voltage
is outside of the ±10% regulation window.
Design files for this circuit board are available at
http://www.linear.com/demo/DC1757B
(TA = 25°C)
PARAMETER CONDITIONS VALUE
Input Voltage Range 6V to 36V
Output Voltage, VOUT VIN = 6V to 36V, IOUT = 0A to 12A 12V ±2%
Maximum Output Current, IOUT VIN = 6V to 36V, VOUT = 12V 12A
Typical Output Ripple VIN = 36V, IOUT = 12A (20MHz BW) 109mVP–P
Typical Efficiency VIN = 12V, VOUT = 12V, IOUT = 12A 97.9%
Typical Switching Frequency 200kHz
Quick start proceDure
Demonstration circuit 1757B is easy to set up to evaluate
the performance of the LTC3789. Refer to Figure 1 for
the proper measurement equipment setup and follow the
procedure below:
1. With power off, connect the input power supply to VIN
(6V to 36V) and GND (input return).
2. Connect the 12V output load between VOUT and GND
(Initial load: no load).
3. Connect the DVMs to the input and outputs.
4. Turn on the input power supply and check for the proper
output voltages. VOUT should be 12V ±2%.
5. Once the proper output voltages are established, ad-
just the loads within the operating range and observe
the output voltage regulation, ripple voltage and other
parameters.
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dc1757bf
DEMO MANUAL DC1757B
Quick start proceDure
Figure 1. Proper Measurement Equipment Setup
Figure 2. Measuring Output Voltage Ripple
+ –
VOUT GND
COUT
Note: 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.
Additional Notes:
1. Usually, the worst case efficiency at full load is at 6VIN.
The board can deliver more output power at higher VIN.
2. R2 is needed for additional/constant output current
limit only.
+–+–
+
–
+
–
+
–
+
–
LOAD
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dc1757bf
DEMO MANUAL DC1757B
Figure 3. Efficiency vs Load Current (VO = 12V, CCM)
Quick start proceDure
parts List
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 CC1 CAP., C0G, 100pF, 50V, 10% 0603 AVX, 06035A101KAT2A
2 1 CC2 CAP., X7R, 0.01µF, 50V, 10% 0603 AVX, 06035C103KAT2A
3 2 CSS, C15 CAP., X7R, 0.1µF, 50V, 10% 0603 AVX, 06035C104KAT2A
4 1 C11 CAP., NPO, 68pF, 50V, 10% 0603 AVX, 06035A680KAT2A
5 1 C10 CAP., X5R, 2.2µF, 10V, 10% 0603 AVX, 0603ZD225KAT2A
6 1 C24 CAP., X7R, 1µF, 16V, 20% 0603 AVX, 0603YC105MAT2A
7 2 CIN1, CIN2 CAP., ALUM, 270µF, 50V, 20% SUN ELECTRONICS, 50ME270WX+T
8 2 COUT1, COUT2 CAP., OS-CON, 330µF, 16V, 20% SANYO, 16SEP330M+T
9 6 C16, C17, C19-C21, C28 CAP., X7R, 22µF, 16V, 20% 1210 AVX, 1210YC226MAT2A
10 2 C4, C22 CAP., X7R, 0.22µF, 16V, 20% 0603 AVX, 0603YC224MAT2A
11 5 C9, C14, C25-C27 CAP., X7R, 3.3µF, 50V, 20% 1210 AVX, 12105C335MAT2A
12 1 C18 CAP., X5R, 10µF, 6.3V, 20% 1206 AVX, 12066D106MAT2A
13 2 D4, D7 DIODE, SCHOTTKY 1A, 60V POWERDI123 DIODE INC., DFLS160-7
14 2 D5, D6 DIODE, SCHOTTKY 3A, 40V SMA DIODE INC., B340A-13-F
15 1 D8 DIODE, ZENER 5.1V 350MW SOT23-3 DIODE INC., BZX84C5V1-7-F
16 2 L1 INDUCTOR, 3µH COILCRAFT, XAL1580-302ME
17 3 Q2, Q4, Q6 MOSFET N-CHANNEL INFINEON, BSC027N04LS G
LOAD CURRENT (A)
0
80
EFFICIENCY (%)
98
96
94
92
90
88
86
84
82
100
1 6 7 8 9 10 11 122 3 4 5
VIN = 36V
VIN = 24V
VIN = 12V
VIN = 6V
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dc1757bf
DEMO MANUAL DC1757B
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
18 3 Q3, Q5, Q9 MOSFET N-CHANNEL INFINEON, BSC010NE2LS
19 1 RFB1 RES., CHIP., 113k, 0.1W, 1% 0603 YAGEO, RC0603FR-07113KL
20 1 RFB2 RES., CHIP., 8.06k, 0.1W, 1% 0603 YAGEO, RC0603FR-078K06L
21 3 R18, R19, R32 SENSOR RES., 0.01, 1W, 1% 2512 VISHAY, WSL2512R0100FEA
22 1 R2 SENSE RES 0.003Ω, 1W, 1% 2512 SMD YAGEO, PR2512FKF070R003L
23 6 R3, R4, R9, R10, R13, R14 RES., CHIP., 100, 0.1W, 1% 0603 YAGEO, RC0603FR-07100RL
24 1 R5 RES., CHIP, 5.1, 0.1W, 5% 0805 YAGEO, RC0805JR-075R1L
25 1 R7 RES., CHIP., 100k, 0.1W, 1% 0603 YAGEO, RC0603FR-07100KL
26 1 R8 RES., CHIP., 10, 0.1W, 5% 0603 YAGEO, RC0603JR-0710RL
27 1 R26 RES., CHIP., 10, 0.1W, 5% 0805 YAGEO, RC0805JR-0710RL
28 6 R1, R11, R17, R23, R25, R27 RES., CHIP., 0 1% 0603 YAGEO, RC0603FR-070RL
29 1 R20 RES., CHIP., 0 2512 TEPRO, RN5326
30 1 R16 RES., CHIP., 1k, 0.1W, 1% 0603 YAGEO, RC0603FR-071KL
31 3 RC, R21, R24 RES., CHIP., 10k, 0.1W, 1% 0603 YAGEO, RC0603FR-0710KL
32 1 R30 RES., CHIP., 33.2k, 0.1W, 1% 0603 YAGEO, RC0603FR-0733K2L
33 1 R31 RES., CHIP., 12.1k, 0.1W, 1% 0603 YAGEO, RC0603FR-0712K1L
34 1 U1 I.C., VOLT. REG. LINEAR TECH., LTC3789EGN#PBF
Additional Demo Board Circuit Components
1 0 CF1, CF, C7, C8 (OPT) CAP., 0603
2 0 C23, C29-C32, C35 (OPT) CAP., 1210
3 0 C12, C13 (OPT) CAP., 1206
4 0 Q7, Q8 (OPT) MOSFET
5 0 R6, R12, R15, R22 (OPT) RES., 0603
6 0 R28, R29 (OPT) RES., CHIP., 1206
Hardware-For Demo Board Only
1 2 JP1, JP2 HEADER, 3 PIN, 0.079 SINGLE ROW SAMTEC, TMM-103-02-L-S
2 2 XJP1, XJP2B SHUNT, .079" CENTER SAMTEC, 2SN-BK-G
3 4 J1, J2, J3, J4 CONNECTOR, BANANA JACK KEYSTONE, 575-4
4 4 TP1, TP2, TP3, TP7 TESTPOINT, TURRET, .061" PBF MILL-MAX, 2308-2-00-80-00-00-07-0
5 6 TP4, TP5, TP6, TP10-TP12 TESTPOINT, TURRET, .094" PBF MILL-MAX, 2501-2-00-80-00-00-07-0
6 4 MTGS AT 4 CORNERS STAND-OFF, NYLON 0.5" KEYSTONE, 8833 (SNAP ON)
parts List
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dc1757bf
DEMO MANUAL DC1757B
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
schematic Diagram
5
5
4
4
3
3
2
2
1
1
D D
C C
B B
A A
2. INSTALL SHUNTS AS SHOWN.
1. ALL RESISTORS ARE IN OHMS, 0603.
ALL CAPACITORS ARE IN MICROFARADS, 0603.
NOTE: UNLESS OTHERWISE SPECIFIED
16V
6.3V
(OPT) (OPT)
(OPT)
MODE
2512
CCM
PULSE SKIP
0805
(OPT)
(OPT)
XAL1580-302ME
VOS+
VOS+
VOUT
VIN+
VOUT
INTVCC
VOUT
INTVCC
VIN+
VOUT1
INTVCC
VIN+
INTVCC
SIZE
DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE 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. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. SCALE = NONE
www.linear.com
1
Tuesday, February 28, 2017
11
HIGH EFFICIENCY 12V / 12A BUCK-BOOST CONVERTER
HZ
JW
N/A
LTC3789EGN
DEMO CIRCUIT 1757B
SIZE
DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE 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. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. SCALE = NONE
www.linear.com
1
Tuesday, February 28, 2017
11
HIGH EFFICIENCY 12V / 12A BUCK-BOOST CONVERTER
HZ
JW
N/A
LTC3789EGN
DEMO CIRCUIT 1757B
SIZE
DATE:
IC NO. REV.
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: (408)434-0507
Milpitas, CA 95035
Phone: (408)432-1900
1630 McCarthy Blvd.
LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
LINEAR TECHNOLOGY HAS MADE 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. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. SCALE = NONE
www.linear.com
1
Tuesday, February 28, 2017
11
HIGH EFFICIENCY 12V / 12A BUCK-BOOST CONVERTER
HZ
JW
N/A
LTC3789EGN
DEMO CIRCUIT 1757B
REVISION HISTORY
DESCRIPTION DATE
APPROVED
ECO REV
JW
PRODUCTION1 2-22-17
1
REVISION HISTORY
DESCRIPTION DATE
APPROVED
ECO REV
JW
PRODUCTION1 2-22-17
1
REVISION HISTORY
DESCRIPTION DATE
APPROVED
ECO REV
JW
PRODUCTION1 2-22-17
1
C4
0.22uF
16V
R17 0
TP7 GND
R11 0
C22
0.22uF
16V
R26 10
R29
(OPT)
R27 0
C10
2.2uF
R14
100
R25
0
R9 100
R5
5.1
R7
100K
R15 OPT
R19
0.01
1W
CC2
0.01uF
CF1 OPT
C17
22uF
16V
C29
TP12
EXTVCC
C23
1210
Q2
BSC027N04LS
G
DS
R8
10
R32
0.01
1W
R10 100
C18 10uF
R1 0
R28
(OPT)
1206
R6 OPT
RC
10K
JP1
ON
OFF
RUN
1
3
2
C13
(OPT)
R16 1K
TP6
ITH
CSS
0.1uF
J1 VIN
6V - 36V
D6
B340A
D7
DFLS160
Q6
G
DS
D5
B340A
C19
22uF
16V
+
CIN1
270uF
50V
C11
68pF
C35
3.3uF
50V
1210
+
COUT1
330uF
16V
C31
C7 OPT
JP2
1
3
2
R2 0.003
1W
TP3 VIN+
C27
Q9
BSC010NE2LS
G
DS
RFB2 8.06K
D8
BZX84C5V1
C16
22uF
16V
J2 GND
R12 OPT
R24
10K
R18
0.01
1W
+
CIN2
270uF
50V
Q8
BSC010NE2LS
G
DS
R23 0
L1 3uH
C20
22uF
16V
TP5
SS
C26
C32
Q3
G
DS
R3 100
TP11
SGND
Q5
G
DS
C14
3.3uF
50V
1210
C12
(OPT)
1206
J3 VOUT
12V @ 12A MAX
R30
41.2K
R21
10K
CC1 100pF
C8 OPT
C9
3.3uF
C28
22uF
16V
1210
TP2 VOS+
TP4
PGOOD
C15
0.1uF
50V
R22
OPT
R13
100
Q7
BSC027N04LS
Q4
G
DS
R20 0
CF
OPT
C25
50V
1210
C21
22uF
16V
J4 GND
C24 1uF
RFB1
113K
+
COUT2
330uF
16V
U1
LTC3789EGN
VFB
1
SS
2
SENSE1+
3
SENSE1-
4
ITH
5
SGND
6
MODE/PLLIN
7
FREQ
8
RUN
9
VINSNS
10
VOUTSNS
11
ILIM
12
IOSENSE+
13
IOSENSE-
14
TRIM
15
SW2
16
TG2
17
BOOST2
18
BG2
19
EXTVCC
20
INTVCC
21
VIN
22
PGND
24
BOOST1
25
SW1
27
PGOOD
28
TG1
26
BG1
23
C30
D4
DFLS160
TP10
PLLIN
R31
12.1K
TP1 VOS-
R4 100
6
dc1757bf
DEMO MANUAL DC1757B
LINEAR TECHNOLOGY CORPORATION 2017
LT 0317 • PRINTED IN USA
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
