DEMO MANUAL
DC1731A-A/DC1731A-B
LTC3646/LTC3646-1
High Efficiency Low Quiescent Current
Step-Down Converter
DESCRIPTION
Demonstration circuit 1731A-A/1731A-B is a step-down
DC/DC converter using LTC3646/LTC3646-1 monolithic
synchronous buck regulator. The input voltage range is
from 4V to 40V. The output voltage range of LTC3646 is
2V to 30V, for LTC3646-1 is 0.6V to 15V. It can deliver up
to 1A of output current. At light load conditions, DC1731A
can operate in Burst Mode® operation to improve the efficiency. The user can choose to use internal or external
compensation. The switching frequency of LTC3646/
LTC3646-1 is programmable from 200kHz to 3MHz. It can
PERFORMANCE SUMMARY
PARAMETER
be synchronized to an external clock through the MODE/
SYNC pin. The LTC3646/LTC3646-1 data sheet must be
read in conjunction with this demo manual prior to working
on or modifying demonstration circuit 1731A.
Design files for this circuit board are available at
http://www.linear.com/demo
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.
Specifications are at TA = 25°C
CONDITIONS/NOTES
Input Voltage Range
Output Voltage VOUT
VALUE
4V to 40V
Jumper Selectable
Maximum Continuous Output Current
3.3V, 5V
1A
Default Operating Frequency
1.5MHz
Efficiency
VIN = 12V, VOUT = 5V, IOUT = 1A
Load Transient
VIN = 12V, VOUT = 5V
91.0% See Figure 3
See Figure 4
dc1731aabf
1
DEMO MANUAL
DC1731A-A/DC1731A-B
QUICK START PROCEDURE
Demonstration circuit 1731A is an easy way to evaluate
the performance of the LTC3646/LTC3646-1. Please refer
to Figure 1 for proper measurement equipment setup and
follow the procedure below:
3. Turn on the power at the input. Increase VIN to 12V (Do
not hot-plug the input supply or apply more than the
rated maximum voltage of 40V to the board or the
part may be damaged). The output voltage should be
regulated and deliver the selected output voltage ±2%.
1. Place jumpers in the following positions for a typical
application:
MODE
EXTVCC
RUN
VOUT SELECT
FCC
GND
ON
3.3V
4. Vary the input voltage from 4V to 40V and adjust the
load current from 0A to 1A. Observe the output voltage
regulation, ripple voltage, efficiency, and other parameters.
2. With power off, connect the input power supply, load
and meters as shown in Figure 1. Preset the load to 0A
and VIN supply to be 0V.
5. To measure input or output ripple, please refer to Figure 2
for proper measurement setup.
+
+
+
–
VIN
–
+
–
+
LOAD
–
+
Figure 1. Proper Measurement Equipment Setup
dc1731aabf
2
DEMO MANUAL
DC1731A-A/DC1731A-B
QUICK START PROCEDURE
INPUT OR OUTPUT CAPACITOR
Figure 2. Measuring VIN or VOUT Ripple
LTC3646 Efficiency, VOUT = 5V
100
100
90
90
80
80
70
70
EFFICIENCY (%)
EFFICIENCY (%)
LTC3646 Efficiency, VOUT = 3.3V
60
50
40
30
VIN = 5V
VIN = 12V
VIN = 18V
VIN = 24V
VIN = 36V
20
10
0
0
0.2
0.4
0.6
LOAD (A)
0.8
1.0
60
50
40
30
VIN = 12V
VIN = 18V
VIN = 24V
VIN = 36V
20
10
0
0
0.2
0.4
0.6
LOAD (A)
dc1731aab F03a
(a)
0.8
1.0
dc1731aab F03b
(b)
Figures 3a and 3b. Measured DC1731A Efficiency at Different VIN and VOUT (Burst Mode Operation Enabled)
VOUT: 100mV/DIV
IOUT_STEP: 500mA/DIV
dc1731aab F04
VIN = 12V
VO = 5V
0A TO 0.5A LOAD STEP
Figure 4. Measured Load Transient Responses
dc1731aabf
3
DEMO MANUAL
DC1731A-A/DC1731A-B
PARTS LIST
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Required Circuit Components
1
1
U1
IC, HIGH EFFICIENCY LOW QUIESCENT CURRENT
STEP-DOWN CONVERTER
LTC3646EDE FOR DC1731A-A LTC3646EDE-1 FOR
DC1731A-B
2
2
CIN2, CIN3
CAP, 1210 10μF 20% 50V X5R
TAIYO YUDEN UMK325BJ106MM-T
3
1
COUT1
CAP, 1210 4.7μF 20% 16V X7R
TAIYO YUDEN EMK325BJ475MN-T
4
1
COUT2
CAP, 1210 10μF 20% 16V X5R
TDK C3225X7R1C106M
5
1
C1
CAP, 0603 4.7μF 10% 10V X5R
TDK C1608X5R1A475K-T
6
1
C2
CAP, 0603 0.1μF 10% 50V X7R
AVX 06035C104KAT2A
7
1
C3
CAP, 0603 5.6pF 0.25pF 50V NPO
AVX 06035A5R6CAT2A
8
1
C5
CAP, 0603 100pF 10% 50V X7R
AVX 06035C101KAT2A
9
1
C6
CAP, 0805 2.2μF 20% 50V Y5V
TDK C2012Y5V1H225Z
10
2
C7, C9
CAP, 0805 1μF 10% 50V X7R
MURATA GRM21BR71H105KA12L
11
1
L1
IND, 4.7μH
COILCRAFT XAL5030-472MEB
12
1
R2
RES, 0603 2Ω 5% 1/10W
VISHAY CRCW06032R00FNEA
13
1
R3
RES, 0603 100kΩ 5% 1/10W
VISHAY CRCW0603100KJNEA
14
1
R7
RES, 0603 60.4kΩ 1% 1/10W
VISHAY CRCW060360K4FKED
15
1
R9
RES, 0603 200kΩ 1% 1/10W
VISHAY CRCW0603200KFKEA
16
1
R10
RES, 0603 137kΩ 1% 1/10W
YAGEO RC0603FR-07137KL
17
1
R11
RES, 0603 84.5kΩ 1% 1/10W
VISHAY CRCW060384K5FKEA
18
1
R12
RES, 0603 619kΩ 1% 1/10W
VISHAY CRCW0603619KFKEA
Additional Demo Board Circuit Components
1
0
CIN1
CAP, 56μF 20% 50V ALUM. ELEC. OPTION
SUN ELEC 50HVH56M OPTION
2
0
C4, C8
CAP, 0603 OPTION
OPTION
3
0
D1
DIODE, OPTION
OPTION
4
0
R4, R5, R6
RES, 0603 OPTION
OPTION
Hardware: For Demo Board Only
1
11
E1-E11
TURRET
MILL-MAX 2501-2-00-80-00-00-07-0
2
1
JP1
HEADER, 2mm, 3PIN
SAMTEC TMM-103-02-L-S
3
2
JP2, JP5
HEADER, 3PIN, DBL ROW 2mm
SAMTEC TMM 103-02-L-D
4
1
JP3
HEADER, 2mm DBL ROW (2X2) 4PIN
SAMTEC TMM-102-02-L-D
5
4
MH1, MH2, MH3, MH4
STANDOFF, SNAP ON
KEYSTONE_8831
6
4
JP1, JP2, JP3, JP5
SHUNT, 2mm
SAMTEC 2SN-BK-G
dc1731aabf
4
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.
A
B
C
D
E10
E9
E5
INTVCC
CIN2
10uF
50V
1210
4
6
5
BURST
R5
OPT
FCC
SYNC
JP2
2
3
MODE / SYNC
R3
100k
+ CIN1
OPT
1
INTVCC
PG
VIN
INTVCC
CIN3
10uF
50V
1210
R6
OPT
R7
60.4k
1%
[3]
[2]
VERSION
VIN
5
IC
VOUT
JP1
R4
3
2
1
R9
200k
1%
C4
OPT
0805
1uF
C7
3
4
7
6
13
U1
[3]
R2
2
ITH
RT
0805
C8
INTVCC
OPT
C6
2.2uF 50V
MODE/SYNC
PGOOD
RUN
2
5
9
10
4
3
7+,6&,5&8,7,635235,(7$5<72/,1($57(&+12/2*<$1'
6833/,(')2586(:,7+/,1($57(&+12/2*<3$576
3
C1
4.7uF
L1 4.7uH
REV
5
3
1
R10
137k
1%
'$7(
N/A
6,=(
R11
84.5k
1%
R12
619k
1%
TECHNOLOGY
VOUT
C9
1uF
0805
E11
E3
GND
GND
VOUT
[2]
GND
INTVCC
EXTVCC
3
0F&DUWK\%OYG
0LOSLWDV&$
3KRQH ZZZOLQHDUFRP
)D[
/7&&RQILGHQWLDO)RU&XVWRPHU8VH2QO\
COUT2
10uF
16V
1210
E4
E7
E6
DATE
09/21/12
2
10/04/12 10:19:29
1
6+((7 1
DEMO CIRCUIT 1731A-A/B
2) 1
HIGH EFFICIENCY LOW QUIESCENT
CURRENT STEP-DOWN CONVERTER
,&12LTC3646EDE / LTC3646EDE-1
5(9
7,7/( 6&+(0$7,&
VOUT SELECT
JP3
6
COUT1
4.7uF
16V
1210
EXTVCC
4
JP5
VOUT
GND
2
E8
YAN L.
VOUT
APPROVED
PROTO
1
DESCRIPTION
EXTVCC
C3
5.6pF
COILCRAFT
XAL5030-472MEB
C2 0.1uF
D1
DFLS1200
OPT
SW
6&$/( 121(
ECO
EXTVCC
$33529$/6
VFB
VON
SW
BOOST
/,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 3&%'(6 0,
9(5,)<3523(5$1'5(/,$%/(23(5$7,21,17+($&78$/
$33(1* <$1/
$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&(
&86720(5127,&(
C5
100pF
OPT
RUN
INTVCC
OFF
ON
NOTES: UNLESS OTHERWISE SPECIFIED,
1. ALL RESISTOR AND CAPACITOR CASE SIZE ARE 0603.
SYNC
PGOOD
GND
[2]
VIN
E2
SVIN
8
PVIN
SVIN
1
E1
14
SVIN
SGND
12
EXTVCC
PGND
15
11
INTVCC
REVISION HISTORY
5V
2
3.3V
3
2
1
4
4
3
5
A
B
C
D
DEMO MANUAL
DC1731A-A/DC1731A-B
SCHEMATIC DIAGRAM
dc1731aabf
5
DEMO MANUAL
DC1731A-A/DC1731A-B
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
dc1731aabf
6
Linear Technology Corporation
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●
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