DEMO MANUAL DC2141A
LTM4647
30A DC/DC Step-Down
µModule Regulator
DESCRIPTION
Demonstration circuit 2141A features the
LTM
®
4647EY,
a 30A high efficiency, switch mode step-down power
µModule regulator. The input voltage range is from 6V to
15V. To use DC2141A for input voltage range from 4.7V to
6V, connect INTVCC to SVIN (change R22 from OPT to 0Ω),
DRVCC to VIN (change R21 from 0Ω to OPT, R28 from OPT
to 0Ω). The output voltage range is 0.6V to 1.8V. Derating
is necessary for certain VIN, VOUT, frequency and thermal
conditions. The DC2141A offers the TRK/SS pin allowing
the user to program output tracking or soft-start period. The
board operates in continuous conduction mode in heavy
load conditions. For high efficiency at low load currents,
the MODE_PLLIN jumper selects pulse-skipping mode for
noise sensitive applications or Burst Mode
®
operation in
less noise sensitive applications. The MODE_PLLIN pin
also allows the LTM4647 to synchronize to an external
clock signal (between 400kHz and 800kHz). DC2141A
has the option of choosing both internal and external
compensation circuit for LTM4647. Tying the PHASMD
pin to different voltage generates certain phase difference
between MODE_PLLIN and CLKOUT. The LTM4647 data
sheet must be read in conjunction with this demo manual
prior to working on or modifying demo circuit DC2141A.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2141A
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.
BOARD PHOTO
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DEMO MANUAL DC2141A
PERFORMANCE SUMMARY
PARAMETER
Input Voltage Range
Output Voltages
Maximum Continuous Output Current
Operating Frequency
Efficiency
Load Transient
R
FB
= 90.9kΩ
Derating Is Necessary for Certain Operating Conditions.
See Data Sheet for Details
R
FREQ
= 47.5kΩ
V
IN
= 12V, V
OUT
= 1.0V, I
OUT
= 30A
V
IN
= 12V, V
OUT
= 1.0V, I
STEP
= 5A to 20A
CONDITIONS
Specifications are at T
A
= 25°C
MIN
6
1.0 ±1.0%
30
600
86.2 Figure 2
153 Figure 3
TYP
MAX
15
UNITS
V
V
ADC
kHz
%
mV
QUICK START PROCEDURE
Demonstration circuit 2141A is an easy way to evaluate the
performance of the LTM4647EY. 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
application:
MODE
CCM
RUN
ON
4. Vary the input voltage from 6V to 15V and adjust the
load current from 0A to 30A. Observe the output volt-
age regulation, ripple voltage, efficiency, and other
parameters.
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.
6. (Optional) LTM4647 can be synchronized to an external
clock signal. Place the JP1 jumper on EXT_CLK and
apply a clock signal (0V to 5V, square wave) on the
MODE_PLLIN test point.
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 12V.
3. Turn on the power supply at the input. The output volt-
age should be 1.0V ±1.0% (0.99V to 1.01V).
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DEMO MANUAL DC2141A
QUICK START PROCEDURE
+
–
+
V
IN
+
–
+
LOAD
–
–
Figure 1. Measurement Set-Up of DC2141A
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DEMO MANUAL DC2141A
QUICK START PROCEDURE
12V
IN
Efficiency
95
90
85
EFFICIENCY (%)
80
75
70
65
60
55
50
0
5
15
10
20
OUTPUT CURRENT (A)
1V
OUT
1.5V
OUT
25
30
dn2141a F02
Figure 2. Measured Efficiency at V
IN
= 12.0V, f
SW
= 600kHz, CCM
V
OUT
: 100mV/DIV
I
OUT_STEP
: 10A/DIV
dn2141a F03
Figure 3. Measured Load Transient, V
IN
= 12V, V
OUT1
= 1.0V, I
STEP
= 5A to 20A
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DEMO MANUAL DC2141A
QUICK START PROCEDURE
Figure 4. Thermal Image of LTM4647, V
IN
= 12V, V
OUT
= 1.0V, I
LOAD
= 30A, T
A
= 23.0°C, No Forced Air Flow
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