Linear Technology DC1872A User manual

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dc1872af
DEMO MANUAL DC1872A
DESCRIPTION
LTM4637
20A DC/DC µModule
Step-Down Regulator
DemonstrationcircuitDC1872AfeaturestheLT M
®
4637EV,
a high efficiency, high density switch mode step-down
power µModule
®
regulator. The input voltage range is
from 4.5V to 20V. The output voltage is jumper pro-
grammable from 1.0V to 1.8V with a rated load current
of 20A. Derating is necessary for certain VIN, VOUT, fre-
quency and thermal conditions. The DC1872A offers the
TRACK/SS pin, allowing the user to program output track-
ing or soft-start period. The DC1872A allows the user to L, LT, LTC, LTM, Linear Technology, the Linear logo, µModule and Burst Mode are registered
trademarks of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
PERFORMANCE SUMMARY
BOARD PHOTO
choose pulse-skipping mode or Burst Mode
®
operation
for higher efficiency at light load conditions.
The LTM4637 data sheet must be read in conjunction with
this demo manual prior to working on or modifying demo
circuit DC1872A.
Design files for this circuit board are available at
http://www.linear.com/demo
PARAMETER CONDITIONS / NOTES VALUE
Input Voltage Range 4.5V to 20V
Output Voltage VOUT Jumper Selectable 1.0V, 1.2V, 1.5V, 1.8V ±1.5%
Maximum Continuous Output Current Derating Is Necessary for Certain Operating
Conditions. See Data Sheet for Details
20ADC
Operating Frequency RfSET =124kΩ 520kHz
Efficiency VIN = 12V, VOUT = 1.0V, IOUT = 20A 82.2% See Figure 2
Load Transient VIN = 12V, VOUT = 1.0V See Figure 3

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DEMO MANUAL DC1872A
QUICK START PROCEDURE
Demonstration circuit DC1872A is an easy way to eva-
luate the performance of the LTM4637EV. Please refer to
Figure 1 for proper measurement equipment setup and
follow the procedure below:
1. Place jumpers in the following positions for a typical
1.0VOUT application:
RUN MODE TRACK/SS VOUT SELECT
ON CCM SS 1.0V
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.
3. Turn on the power at the input. Increase VIN to 12V (Do
not apply more than the rated maximum voltage of
20V to the board or the part may be damaged). The
output voltage should be regulated and deliver the
selected output voltage ±1.5%.
4. Vary the input voltage from 4.5V to 20V and adjust
the load current from 0A to 20A. Observe the output
voltage regulation, ripple voltage, efficiency, and other
parameters. Output voltage ripple may be measured at
J4witha BNC cable andoscilloscope. The probechannel
for VOUT should be set at 50Ω termination resistance
to match the BNC cable.
5. (Optional) For optional load transient test, apply an
adjustable pulse signal between IOSTEP_CLK and GND
test points. The pulse amplitude sets the load step cur-
rent amplitude. Keep the pulse width short (<1ms) and
pulse duty cycle low (<5%) to limit the thermal stress
on the load transient circuit. The load step current can
be monitored with a BNC connected to J3 (15mV/A).
V
+
–
A
–
+
A
–+
LOAD
+
–
+
–
V
+
–
DC1872A F01
VIN
Figure 1. Proper Measurement Equipment Setup

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DEMO MANUAL DC1872A
QUICK START PROCEDURE
LOAD (A)
0
0
EFFICIENCY (%)
10
30
40
50
100
70
510
DC1872A F02a
20
80
90
60
15 20
VIN = 5V
VIN = 8V
VIN = 12V
VIN = 16V
VIN = 20V
(2a) VOUT = 1.0V (2c) VOUT = 1.5V
(2b) VOUT = 1.2V (2d) VOUT = 1.8V
LOAD (A)
0
0
EFFICIENCY (%)
10
30
40
50
100
70
510
DC1872A F02b
20
80
90
60
15 20
VIN = 5V
VIN = 8V
VIN = 12V
VIN = 16V
VIN = 20V
LOAD (A)
0
0
EFFICIENCY (%)
10
30
40
50
100
70
510
DC1872A F02c
20
80
90
60
15 20
VIN = 5V
VIN = 8V
VIN = 12V
VIN = 16V
VIN = 20V
LOAD (A)
0
0
EFFICIENCY (%)
10
30
40
50
100
70
510
DC1872A F02d
20
80
90
60
15 20
VIN = 5V
VIN = 8V
VIN = 12V
VIN = 16V
VIN = 20V
Figure 2. Measured DC1872A Efficiency at Different VIN and VOUT Values (CCM Mode Enabled)
Figure 3. Measured Load Transient Response
(VIN = 12V, VOUT = 1.0V, 0A to 10A Load Step)
Figure 4. Thermal Image of LTM4637 (VIN = 12V, VOUT = 1.0V,
ILOAD = 20A, Ambient Temperature = 21.6°, No Forced Air Flow)
VOUT
100mV/DIV
IOUT_STEP
6.67A/DIV
DC1872A F03

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DEMO MANUAL DC1872A
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 U1 IC, MICRO MODULE LINEAR TECH LTM4637EV
2 2 C5, C24 CAP, 1210 22µF 10% 25V X5R MURATA GRM32ER61E226KE15L
3 1 C6 CAP, 150µF 35V ELEC SUN ELEC 35CE150AX
4 1 C9 CAP, 0603 0.1µF 10% 50V X7R TDK C1608X7R1H104K
5 1 C10 CAP, 0603 150pF 10% 25V NPO AVX 06033A151KAT2A
6 2 C11, C12 CAP, 1210 100µF 20% 6.3V X5R TDK C3225X5R0J107M
7 1 C16 CAP, 7343 470µF 20% 2.5V POSCAP SANYO 2R5TPE470M9
8 1 C18 CAP, 0603 1.5nF 5% 25V X7R AVX 06033C152JAT2A
9 1 C19 CAP, 0603 82pF 5% 25V NPO AVX 06033A820JAT2A
10 1 R9 RES, 0603 124k 1% 1/10W VISHAY CRCW0603124K0FKEA
11 1 R20 RES. 0603 100k 5% 1/10W VISHAY CRCW0603100KJNEA
12 1 R15 RES, 0603 30.1k 1% 1/10W VISHAY CRCW060330K1FKEA
Additional Demo Board Components
1 1 Q1 XSTR, MOSFET, N-CHANNEL 30V VISHAY SUD50N03-09P-GE3
2 1 R1 RES, 0603 10k 5% 1/10W VISHAY CRCW060310K0JNEA
3 1 R2 RES, 2512 0.015Ω 1% 1W VISHAY WSL2512R0150FEA
4 2 R3, R13 RES, 0603 60.4k 1% 1/10W VISHAY CRCW060360K4FKEA
5 2 R4, R12 RES, 0603 90.9k 1% 1/10W VISHAY CRCW060390K9FKEA
6 1 R7 RES, 0603 0Ω JUMPER VISHAY CRCW06030000Z0ED
7 1 R10 RES. 0603 20k 5% 1/10W VISHAY CRCW060320K0JNEA
8 1 R14 RES, 0603 40.2k 1% 1/10W VISHAY CRCW060340K2FKEA
9 2 R18, R19 RES, 0603 10Ω 5% 1/10W VISHAY CRCW060310R0JNEA
10 3 C1, C2, C8 CAP, 0603 1µF 20% 10V X5R TAIYO YUDEN LMK107BJ105MA-T
11 0 C3, C4, C13, C22, C23 CAP, 1210 OPTION OPTION
12 0 C7 CAP, 0805 OPTION OPTION
13 0 C14, C15, C17, C20, C21 CAP, 0603 OPTION OPTION
14 0 R5, R6, R8, R11, R16 RES, 0603 OPTION OPTION
Hardware
1 11 E1-E11 TURRET MILL-MAX 2501-2-00-80-00-00-07-0
2 2 JP1, JP2 HEADER, 3-PIN, 2mm SAMTEC TMM-103-02-L-S
3 4 JP1, JP2, JP3, JP4 SHUNT SAMTEC 2SN-BK-G
4 2 JP3, JP4 HEADER, 4-PIN, DOUBLE ROW, 2mm SAMTEC TMM-104-02-L-D
5 4 J1, J2, J5, J6 JACK, BANANA KEYSTONE 575-4
6 2 J3, J4 CONN., VERT. PC-MNT, BNC 50 OHM CONNEX 112404
7 4 MH1, MH2, MH3, MH4 STANDOFF, SNAP ON KEYSTONE_8834

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DEMO MANUAL DC1872A
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

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DEMO MANUAL DC1872A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] ●FAX: [phone] ●www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2012
LT 1212 • 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

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