DEMO MANUAL DC1872A
LTM4637
20A DC/DC µModule
Step-Down Regulator
DESCRIPTION
Demonstration circuit
DC1872A
features the
LTM
®
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 V
IN
, V
OUT
, 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
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
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
PARAMETER
Input Voltage Range
Output Voltage V
OUT
Maximum Continuous Output Current
Operating Frequency
Efficiency
Load Transient
Jumper Selectable
Derating Is Necessary for Certain Operating
Conditions. See Data Sheet for Details
R
fSET
=124kΩ
V
IN
= 12V, V
OUT
= 1.0V, I
OUT
= 20A
V
IN
= 12V, V
OUT
= 1.0V
CONDITIONS / NOTES
VALUE
4.5V to 20V
1.0V, 1.2V, 1.5V, 1.8V ±1.5%
20ADC
520kHz
82.2% See Figure 2
See Figure 3
BOARD PHOTO
dc1872af
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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
1.0V
OUT
application:
RUN
ON
MODE
CCM
TRACK/SS
SS
VOUT SELECT
1.0V
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
J4 with a BNC cable and oscilloscope. The probe channel
for V
OUT
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).
2. With power off, connect the input power supply, load
and meters as shown in Figure 1. Preset the load to
0A and V
IN
supply to be 0V.
3. Turn on the power at the input. Increase V
IN
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%.
–
V
–
+
LOAD
+
–
+
A
V
2
+
+
–
–
V
IN
+
A
–
DC1872A F01
Figure 1. Proper Measurement Equipment Setup
dc1872af
DEMO MANUAL DC1872A
QUICK START PROCEDURE
100
90
80
EFFICIENCY (%)
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0
5
10
LOAD (A)
V
IN
= 5V
V
IN
= 8V
V
IN
= 12V
V
IN
= 16V
V
IN
= 20V
15
20
DC1872A F02a
100
90
80
70
60
50
40
30
20
10
0
0
5
10
LOAD (A)
V
IN
= 5V
V
IN
= 8V
V
IN
= 12V
V
IN
= 16V
V
IN
= 20V
15
20
DC1872A F02c
(2a) V
OUT
= 1.0V
100
90
80
EFFICIENCY (%)
EFFICIENCY (%)
70
60
50
40
30
20
10
0
0
5
10
LOAD (A)
V
IN
= 5V
V
IN
= 8V
V
IN
= 12V
V
IN
= 16V
V
IN
= 20V
15
20
DC1872A F02b
(2c) V
OUT
= 1.5V
100
90
80
70
60
50
40
30
20
10
0
0
5
10
LOAD (A)
V
IN
= 5V
V
IN
= 8V
V
IN
= 12V
V
IN
= 16V
V
IN
= 20V
15
20
DC1872A F02d
(2b) V
OUT
= 1.2V
(2d) V
OUT
= 1.8V
Figure 2. Measured DC1872A Efficiency at Different V
IN
and V
OUT
Values (CCM Mode Enabled)
V
OUT
100mV/DIV
I
OUT_STEP
6.67A/DIV
DC1872A F03
Figure 3. Measured Load Transient Response
(V
IN
= 12V, V
OUT
= 1.0V, 0A to 10A Load Step)
Figure 4. Thermal Image of LTM4637 (V
IN
= 12V, V
OUT
= 1.0V,
I
LOAD
= 20A, Ambient Temperature = 21.6°, No Forced Air Flow)
dc1872af
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DEMO MANUAL DC1872A
PARTS LIST
ITEM
1
2
3
4
5
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Hardware
1
2
3
4
5
6
7
11
2
4
2
4
2
4
E1-E11
JP1, JP2
JP1, JP2, JP3, JP4
JP3, JP4
J1, J2, J5, J6
J3, J4
MH1, MH2, MH3, MH4
TURRET
HEADER, 3-PIN, 2mm
SHUNT
HEADER, 4-PIN, DOUBLE ROW, 2mm
JACK, BANANA
CONN., VERT. PC-MNT, BNC 50 OHM
STANDOFF, SNAP ON
MILL-MAX 2501-2-00-80-00-00-07-0
SAMTEC TMM-103-02-L-S
SAMTEC 2SN-BK-G
SAMTEC TMM-104-02-L-D
KEYSTONE 575-4
CONNEX 112404
KEYSTONE_8834
QTY
1
2
1
1
1
2
1
1
1
1
1
1
1
1
1
2
2
1
1
1
2
3
0
0
0
0
REFERENCE
U1
C5, C24
C6
C9
C10
C11, C12
C16
C18
C19
R9
R20
R15
Q1
R1
R2
R3, R13
R4, R12
R7
R10
R14
R18, R19
C1, C2, C8
C3, C4, C13, C22, C23
C7
C14, C15, C17, C20, C21
R5, R6, R8, R11, R16
PART DESCRIPTION
IC, MICRO MODULE
CAP, 1210 22µF 10% 25V X5R
CAP, 150µF 35V ELEC
CAP, 0603 0.1µF 10% 50V X7R
CAP, 0603 150pF 10% 25V NPO
CAP, 1210 100µF 20% 6.3V X5R
CAP, 7343 470µF 20% 2.5V POSCAP
CAP, 0603 1.5nF 5% 25V X7R
CAP, 0603 82pF 5% 25V NPO
RES, 0603 124k 1% 1/10W
RES. 0603 100k 5% 1/10W
RES, 0603 30.1k 1% 1/10W
XSTR, MOSFET, N-CHANNEL 30V
RES, 0603 10k 5% 1/10W
RES, 2512 0.015Ω 1% 1W
RES, 0603 60.4k 1% 1/10W
RES, 0603 90.9k 1% 1/10W
RES, 0603 0Ω JUMPER
RES. 0603 20k 5% 1/10W
RES, 0603 40.2k 1% 1/10W
RES, 0603 10Ω 5% 1/10W
CAP, 0603 1µF 20% 10V X5R
CAP, 1210 OPTION
CAP, 0805 OPTION
CAP, 0603 OPTION
RES, 0603 OPTION
MANUFACTURER/PART NUMBER
LINEAR TECH LTM4637EV
MURATA GRM32ER61E226KE15L
SUN ELEC 35CE150AX
TDK C1608X7R1H104K
AVX 06033A151KAT2A
TDK C3225X5R0J107M
SANYO 2R5TPE470M9
AVX 06033C152JAT2A
AVX 06033A820JAT2A
VISHAY CRCW0603124K0FKEA
VISHAY CRCW0603100KJNEA
VISHAY CRCW060330K1FKEA
VISHAY SUD50N03-09P-GE3
VISHAY CRCW060310K0JNEA
VISHAY WSL2512R0150FEA
VISHAY CRCW060360K4FKEA
VISHAY CRCW060390K9FKEA
VISHAY CRCW06030000Z0ED
VISHAY CRCW060320K0JNEA
VISHAY CRCW060340K2FKEA
VISHAY CRCW060310R0JNEA
TAIYO YUDEN LMK107BJ105MA-T
OPTION
OPTION
OPTION
OPTION
Required Circuit Components
Additional Demo Board Components
dc1872af
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DEMO MANUAL DC1872A
SCHEMATIC DIAGRAM
dc1872af
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.
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