1
dc2372af
DEMO MANUAL DC2372A
Description
LTC3121EDE
High Efficiency 15V 1.5A
Synchronous Step-Up Converter
Demonstration circuit 2372A is a 5.5V input, 12V output
at 400mA DC/DC power supply featuring the LT C
®
3121.
The IC includes internal high and low side 1.5A switches
and features selectable PWM or Burst Mode
®
operation
for high efficiency at low output current. The board oper-
ates from an input voltage as low as 1.8V and continues
to operate down to 500mV once started. The output is
fixed at 12V although other voltages between 2.2V and
15V can be selected by resistor changes.
The IC includes soft-start and input current limit, adjust-
able switching frequency with the ability to synchronize
to an external clock, and output overvoltage protection
with output disconnect.
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective
owners.
performance summary
Included on the board are jumpers for ON/OFF and oper-
ating MODE, PWM or BURST. Terminals are included for
connecting VIN and VOUT as well as ON/OFF and SYNC.
The LTC3121 data sheet gives a complete description of the
IC operation and application information. The data sheet
must be read in conjunction with this quick start guide.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2372A
Specifications are at TA = 25°C
PARAMETER CONDITION VALUE
Input Voltage Range 1.8V to 5.5V
Output Voltage VIN = 5V, VOUT Load = 400mA 12V ±3%
Output Current VIN = 5V, VOUT = 12V 400mA
Output Voltage Ripple (PWM Mode) VIN = 5V, VOUT = 12V, VOUT Load = 400mA 40mVP-P
Output Voltage Ripple (Burst Mode Operation) VIN = 5V, VOUT = 12V, VOUT Load = 50mA 200mVP-P
Switching Frequency 1MHz ±15%
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dc2372af
DEMO MANUAL DC2372A
Quick start proceDure
This Demonstration circuit 2372A can be evaluated using
the setup shown in Figure 1.
1. Connect voltmeters to VIN and VOUT, select upper posi-
tions for jumper JP1 (ON) and JP2 (PWM).
2. With input power supply set for 0V, connect the supply
to VIN and GND terminals.
3. Slowly increase the input power supply to 1.8V. Observe
output voltage and verify that it meets the specifications
in the Performance Summary table.
4. Connect a suitable load resistor or active load to the
output terminals and verify that it meets specifications
in the Performance Summary table.
5. Use a scope to monitor the output voltage ripple in
both PWM mode and Burst Mode operation by moving
the mode jumper JP2 to the appropriate position. See
Figure4 for correct method for evaluating output ripple.
6. Note: If jumper JP2 is set for Burst Mode operation,
maximum output current is limited to approximately
100mA at 5VIN.
Figure 1. Proper Measurement Equipment Setup
6V, 3A
Adjustable
Power Supply LOAD
+
–
+
–
3
dc2372af
DEMO MANUAL DC2372A
Figure 4. Measuring Output Voltage Ripple
Figure 2. Efficiency VIN = 2V Figure 3. Efficiency VIN = 5V
Quick start proceDure
100
10
90
70
50
30
80
60
40
20
0
LOAD CURRENT (mA)
EFFICIENCY (%)
dc2372a F02
0.1 100
1000
101
Burst Mode
OPERATION
PWM MODE
100
10
90
70
50
30
80
60
40
20
0
LOAD CURRENT (mA)
EFFICIENCY (%)
dc2372a F03
0.1 100
1000
101
Burst Mode
OPERATION
PWM MODE
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dc2372af
DEMO MANUAL DC2372A
parts List
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
1 1 C1 CAP 10μF X5R 10V 10%1206 TDK, C3216X5R1A106K
2 1 C2 CAP 0.10μF X7R 50V 10% 0603 TDK, CGA3E2X7R1H104K080AA
3 1 C3 CAP 4.7μF X5R 25V 10% 0805 TDK,C2012X5R1E475K085AC
4 0 C4 CAP 0402 OPT OPT
5 1 C5 CAP 22μF 25V X5R 10% 1210 MURATA, GRM32ER61E226KE15L
6 1 C7 CAP 1μF X7R 25V 10% 0603 TDK, CGA3E1X7R1E105K080AC
7 1 C8 CAP 1nF 50V X7R 10% 0402 AVX, 04025C102KAT2A
8 1 C9 CAP 10pF C0G 25V 5% 0402 AVX, 04023A100JAT2A
9 6 E1-E6 TEST POINT, TURRET, 0.094 MTG. HOLE MILL-MAX, 2501-2-00-80-00-00-07-0
10 2 JP2, JP1 CONN, HEADER, 1 × 3, 2mm SAMTEC, TMM-103-02-L-S
11 2 XJP1, XJP2 SHUNT, 2mm SAMTEC, 2SN-BK-G
12 1 L1 IND, PWR 6.8μH, 20%, XAL40xx Series COILCRAFT, XAL4030-682ME
13 1 R1 RES, 1MΩ 1/10W 1% 0402 PANASONIC, ERJ2RKF1004X
14 1 R2 RES, 57.6kΩ 1/10W 1% 0402 PANASONIC, ERJ2RKF5762X
15 0 R3 RES,0402 OPT OPT
16 1 R4 RES 1.02MΩ 1/10W 1% 0402 VISHAY, CRCW04021M02FKED
17 1 R5 RES, 113kΩ 1/10W 1% 0402 PANASONIC, ERJ2RKF1133X
18 1 R6 RES, 82.5kΩ 1/10W 1% 0402 PANASONIC, ERJ2RKF8252X
19 1 U1 IC, LTC3121EDE LINEAR TECH, LTC3121EDE
20 4 STAND OFF STAND-OFF, NYLON 0.500" KEYSTONE, 8832 (SNAP ON)
21 1FAB, PRINTED CIRCUIT BOARD LINEAR TECH, DEMO CIRCUIT 2372A
22 2 STENCILS, TOP & BOTTOM LINEAR TECH, DEMO CIRCUIT 2372A
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dc2372af
DEMO MANUAL DC2372A
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
DD
C C
BB
A A
NOTE: UNLESS OTHERWISE SPECIFIED
2. INSTALL SHUNTS AS SHOWN.
1%
XAL4030
ON
OFF
1. ALL RESISTORS ARE 0402 AND CAPACITORS ARE 0603.
RUN
MODE
BURST
PWM
50V
1%
1%
0402
0402
0402
0805
1%
1%
1%
400mA
VCC
VIN
VCC
VOUT
REVISION HISTORY
DESCRIPTION DATEAPPROVEDECO REV
12-5-14PROTOTYPE
1Goran P.
__
REVISION HISTORY
DESCRIPTION DATEAPPROVEDECO REV
12-5-14PROTOTYPE
1Goran P.
__
REVISION HISTORY
DESCRIPTION DATEAPPROVEDECO REV
12-5-14PROTOTYPE
1Goran P.
__
SIZE
DATE:
.VER.ON CI
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
DEMO CIRCUIT 2372A
11
15V, 1.5A SYNCHRONOUS BOOST DC / DC CONVERTER
N/A
LTC3121EDE
HZ
Goran P.
05 - 16 - 12
SIZE
DATE:
.VER.ON CI
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
DEMO CIRCUIT 2372A
11
15V, 1.5A SYNCHRONOUS BOOST DC / DC CONVERTER
N/A
LTC3121EDE
HZ
Goran P.
05 - 16 - 12
SIZE
DATE:
.VER.ON CI
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
DEMO CIRCUIT 2372A
11
15V, 1.5A SYNCHRONOUS BOOST DC / DC CONVERTER
N/A
LTC3121EDE
HZ
Goran P.
05 - 16 - 12
U1
LTC3121EDE
U1
LTC3121EDE
PGND
2
SHDN/
9
VIN
3
CAP 12
SW 1
FB 8
PWM/SYNC
4
GND
10
RT
6
VOUT 11
GND
13
VCC 5
VC 7
R6
82.5k
R6
R4
1.02M
R4
1.02M
C1
10uF
10V
1206
C1
10uF
10V
1206
L1
6.8uH
L1
6.8uH
R3
OPT
R3
OPT
C5
22uF
25V
1210
C5
22uF
25V
1210
C7
1uF
25V
C7
1uF
25V
JP1JP1
1
3
2
E4
SYNC
E4
SYNC
R5
113K
R5
113K
C3
4.7uF
C3
4.7uF
C2
0.1uF
C2
0.1uF
C8
1nF
C8
E6
GND
E6
GND
C9
10pF
C9
10pF
JP2JP2
1
3
2
E3
RUN
E3
RUN
R2
57.6k
R2
57.6k
C4
OPT
C4
OPT
R1
1M
R1
1M
E5
VOUT
12V
E5
VOUT
12V
E2
GND
E2
GND
E1
VIN
1.8V - 5.5V
E1
VIN
1.8V - 5.5V
6
dc2372af
DEMO MANUAL DC2372A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2015
LT 0715 REV A • PRINTED IN USA
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LT C ) 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 LT C 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 LT C 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. LT C assumes no liability for applications assistance,
customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind.
LT C 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 LT C applica-
tion engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
