DC2008A - Demo Manual

DEMO MANUAL DC2008A
LTC1625
High Efficiency
Synchronous Buck Converter
DESCRIPTION
Demonstration circuit DC2008 is DC/DC buck converter
featuring the LTC®1625 constant frequency current mode
buck controller. The DC2008A operates over a 4.5V to
28V input and provides 15A of output current as shown
in Figure 3. The 225kHz constant frequency operation
results in a small and efficient circuit. The converter provides high output voltage accuracy (typically ±3%) over a
wide load range with no minimum load requirement. The
demonstration circuit can be easily modified to generate
different output voltages.
PERFORMANCE SUMMARY
The DC2008 has small circuit footprint. It is a high performance and cost effective solution for telecom, automotive
and industrial applications.
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.
Specifications are at TA = 25°C
PARAMETER
CONDITIONS
UNITS
Minimum Input Voltage
IOUT = 0A to 15A
4.5V
Maximum Input Voltage
IOUT = 0A to 15A
28V
VOUT
VIN = 4.5V to 28V, IOUT = 0A to 15A
3.3V ±3%
Typical Output Ripple VOUT
VIN = 4.5V to 28V, IOUT = 15A
50mVP-P
Nominal Switching Frequency
225kHz
QUICK START PROCEDURE
Demonstration circuit DC2008 is easy to set up to evaluate
the performance of the LTC1625. For proper measurement equipment setup refer to Figure 1 and follow the
procedure below:
Note: When measuring the input or output voltage ripple,
care must be taken to minimize the length of oscilloscope
probe ground lead. Measure the input or output voltage
ripple by connecting the probe tip directly across the VIN
or VOUT and GND terminals as shown in Figure 2.
1.With power off, connect the input power supply to VIN
and GND.
2.Check the EXTVCC bias voltage-setting jumper JP1.
Remove it for internal VCC bias if required.
3.Turn the input power source on and slowly increase the
input voltage. Be careful not to exceed 28V.
Note: Make sure that the input voltage VIN does not exceed 28V. If higher operating voltage is required, power
components with higher voltage ratings should be used.
4.Set the input voltage to 6V and check for the proper
output voltage of 3.3V. If there is no output, temporarily
disconnect the load to make sure that the load is not
set too high.
5.Once the proper output voltage is established, adjust
the load and observe the output voltage regulation,
ripple voltage, efficiency and other parameters.
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DEMO MANUAL DC2008A
QUICK START PROCEDURE
Figure 1. Proper Measurement Equipment Setup
VIN
GND
Figure 2. Measuring Input or Output Ripple
Changing The Output Voltage
To change the output voltage change the bottom voltage
divider resistors connected to LTC1625 FB pin (see the
Schematic Diagram). Please refer to data sheet for details.
Note that the output voltage will start following the input
voltage when input voltage is lower than the voltage set
by the voltage divider. In this mode the top synchronous
MOSFET is turned continuously ON. The only losses in
this mode are due to the DCR of inductor and top MOSFET
DC resistance. In this mode the LTC1625 has a repetitive
short pulses that are used to refresh the top MOSFET
drive circuit.
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2
DEMO MANUAL DC2008A
QUICK START PROCEDURE
Converter Efficiency And Output Current
The DC2008 output current capability depends on the
components used. Typical performance of DC2008A is
shown in Figure 3.
If bulk input capacitors are required use sufficient numbers
of low ESR type of capacitors like aluminum polymer.
Please consult LTC factory for details on selecting proper
input and output capacitors.
The Schematic Diagram can be modified for lower or
higher currents and output voltages. Please contact LTC
factory for details.
The load step response of DC2008A is very good even
though relatively small amount of output capacitance is
present at the output.
If higher load steps need to be handled or lower transients
are required, more output capacitance can be added in
order to keep the voltage transients at the desired level.
The load step transients are shown in Figure 4. Also, note
that the load step response even from 0% load is excellent
thanks to synchronous operation.
96
94
EFFICIENCY (%)
Output Load Step Response
98
92
90
88
86
84
5V INPUT
12V INPUT
24V INPUT
82
80
0
2
4
6
8 10 12 14 16 18 20 22
IOUT (A)
DC2000A F03
Figure 3. High Efficiency of DC2008 Allows the Board to be Used
in Thermally Critical Applications with Outputs Over 15A
Beware that the load steps on the output will demand
current steps on the input. The DC2008A demo board
responds fast to load transients, which demands fast
response from the input power source. Monitor the input
voltage at the DC2008A input terminals to ensure that the
input power source is capable of supplying such fast load
current demands.
Input And Output Filtering
The DC2008 is equipped with adequate amount of input
and output filtering. The input and output voltage ripples
with a 10A load are shown in Figure 5. Also, the switch
node waveform is shown for reference.
Figure 4. Fast Transient Response of the DC2008 Is Achieved
with a Relatively Small Amount of Output Capacitance
The output ripple voltage will stay constant regardless of
the load. Some of the output capacitors could be removed
at the expense of output ripple voltage and load transient
response.
The input ripple voltage is dependent on the output load
current. The input capacitors were selected based on the
amount of RMS ripple current that needs to be handled.
Beware that adding high ESR electrolytic capacitors at the
input may result in high power dissipation in the capacitors.
Figure 5. The DC2008 Has Very Low Output Ripple Voltage. The
Input Ripple Voltage, if Required, Can Be Further Reduced By
More Input Capacitance of by Adding a Small LC Filter
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3
DEMO MANUAL DC2008A
PARTS LIST
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Required Circuit Components
1
1
CC1
CAP., X7R, 15nF, 25V, 10% 0603
KEMET, C0603C153J3GACTU 2
1
CC2
CAP., X7R, 1nF, 50V, 10% 0603
YAGEO., CC0603KRX7R9BB102
3
1
C3
CAP., X5R, 0.1µF, 16V, 10%, 0603
KEMET, C0603C104K4RACTU
4
1
CF
CAP., X5R, 0.1µF, 50V, 10%, 0603
TDK, CGA3E2X5R1H104K080AA
5
6
CIN1-CIN6
CAP., X5R, 6.8µF, 50V, 10%, 1812
TDK, C4532X7R1H685K
6
2
COUT5, COUT6
CAP., X5R, 100µF, 10V, 20%, 1812
TDK, C4532X5R1A107M280KC
7
4
COUT1-COUT4
CAP., TANT, 680µF,6.3V,7343
KEMET, T530X687M006A1E010
8
1
CVCC1
CAP., X5R, 4.7µF, 6.3V, 10%, 0805
TAIYO YUDEN JMK212BJ475KD-T
9
1
C2
CAP., X7R, 0.47µF, 6.3V, 10%, 0805
TDK, CGJ4J2X7R0J474K 10
1
D2
DIODE, SCHOTTKY, SOD-323
CENTRAL, CMDSH4E
11
1
D3
DIODE., SCHOTTKY, SMA,
DIODE, B340A-13-F
12
1
L1
IND., 3.5µH
WÜRTH ELEKTRONIK, 7443556350
13
2
Q1,Q4
NPN/PNP TRANSISTOR., SC-74
NXP SEMI., PBSS4140DPN
14
1
Q5
N-CHANNEL MOSFET, LFPAK
RENESAS, RJK0453DPB-T-E3
15
1
Q2
N-CHANNEL MOSFET, LFPAK
RENESAS, RJK0452DPB-T-E3
16
1
RC1
RES., CHIP, 15k, 1%, 0603
CRCW060315K0FKEA
17
1
RF
RES., CHIP, 1.0Ω, 1%, 0603
VISHAY,CRCW06031R00FKEA
18
1
R1
RES., CHIP, 10Ω, 1%, 0603
VISHAY, CRCW060310R0FKEA
19
1
R3
RES., CHIP, 0Ω, 0603
VISHAY, CRCW06030R00FKEA
20
1
R4
RES., CHIP, 21k, 1%, 0603
KOA Speer Electronics, RK73H1JTTD2102F
21
1
R5
RES., CHIP, 11.8k, 1%, 0603
VISHAY, CRCW060311K8FKEA
22
1
U1
LTC1625IGN, GN PACKAGE 16-PIN
LINEAR TECH., LTC1625IGN
Additional Demo Board Circuit Components
1
0
CIN7, OPT
CAP., OPTIONAL
2
1
CE
CAP., X5R, 0.1µF, 16V, 10%, 0603
KEMET, C0603C104K4RACTU
3
1
DZ
DIODE., 350mW, 5% ,SOD-323
PHILIPS, PDZ6.8B
4
1
Q3
TRANSISTOR., NPN SOT-89
ZETEX, FCX619
5
1
RZ
RES., CHIP, 4.7k, 5%, 0603
VISHAY, CRCW06034K70JNED
MILL-MAX, 2501-2-00-80-00-00-07-0
Hardware-For Demo Board Only
1
6
E4-E9
TESTPOINT, TURRET, 0.095"
2
4
STAND OFF
STAND OFF
KEYSTONE, 8833
3
1
FAB, PRINTED CIRCUIT BOARD
DEMO CIRCUIT 2008A
4
1
STENCIL TOP AND BOTTOM
STENCIL DC2008A
5
1
JP1
0.079 SINGLE ROW HEADER, 2-PIN
SAMTEC, TMM102-02-LS
6
2
JP2,JP3
0.079 SINGLE ROW HEADER, 3-PIN
SAMTEC, TMM-103-02-L-S
7
3
JP1-JP3
SHUNT
SAMTEC, 2SN-BK-G
8
4
J1-J4
STUD, TEST PIN
PEM KFH-032-10
9
8
J1-J4 (X2)
NUT, BRASS 10-32
ANY #10-32
10
4
J1-J4
RING, LUG #10
KEYSTONE #10
11
4
J1-J4
WASHER, TIN PLATED BRASS
ANY #10
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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
SGND
RUN/SS
E6
E4
5
2
1
3
C
CCM
BURST
INTVCC
JP2
MODE
2
1
3
C3
0.1uF 16V
150KHz
225KHz
JP3
FSW
4
VOUT
CC1
15nF
RC1 15k
DZ
PDZ6.8B
RZ
4.7k
1
2
E
Q3
FCX619
R5
11.8k
21k 1%
R4
CC2
1nF
CE
0.1uF
B
C
7
6
5
4
3
2
1
U1
LTC1625IGN
VOSENSE
SGND
ITH
FCB
RUN/SS
SYNC
EXTVCC
CF
0.1uF 16
VIN
50V
3
VPROG
BG
PGND
INTVCC
BOOST
SW
TK
TG
8
10
9
11
12
14
15
13
1
0
4
1
2
4
1
4
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
2
Q2
L1 3.5uH
D3
B340A
7443556350
SCALE = NONE
HZ
APPROVALS
COUT1
6.8uF
50V
1812
E7
TECHNOLOGY
DATE
E9
J4
J3
E8
-VIN
GND
-VOUT
GND
VOUT
3.3V / 15A
+VOUT
VIN
4.5V - 28V
+VIN
7-31-13
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900 www.linear.com
Fax: (408)434-0507
LTC Confidential-For Customer Use Only
1812
J2
J1
E5
Goran P.
DATE:
N/A
SIZE
1
LTC1625IGN
DEMO CIRCUIT 2008A
Tuesday, October 29, 2013
IC NO.
SHEET 1
OF 1
2
REV.
LTC1625, SYNCHRONOUS STEP-DOWN REGULATOR
TITLE: SCHEMATIC
6.3V
7343
1
APPROVED
VOUT
COUT5
+ COUT6
100uF
10V
+ CIN7
OPT
35V
PRODUCTION
DESCRIPTION
REVISION HISTORY
COUT2
+ COUT3
COUT4
680uF
CIN1
CIN2
CIN3
CIN4
CIN5
CIN6
2
REV
RJK0452DPB
__
ECO
Q5
RJK0453DPB
SW
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A Goran P.
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
PCB DES.
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APP ENG.
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
4
Q4
PBSS4140DPN
R1
10
5
2
PBSS4140DPN
Q1
CUSTOMER NOTICE
R3
5
2
INTVCC
CMDSH-4E
D2
C2
0.47uF
16V
CVCC1
4.7uF
10V
2
EXTVCC
JP1 VIN
6
3
RF
1.0
6
3
5
1
2
3
3
5
1
2
3
4
1
2
D
5
A
B
C
D
DEMO MANUAL DC2008A
SCHEMATIC DIAGRAM
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DEMO MANUAL DC2008A
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
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6
Linear Technology Corporation
LT 1113 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2013
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