DEMO MANUAL DC2268A-B
LTM4620A
Dual 13A or Single 26A
μModule Regulator
Description
Demonstration circuit 2268A-B is a high efficiency, high
density, dual 13A, switch mode step-down power supply
on a compact 1.5' × 1.2' PCB. It features the
LTM4620A
μModule regulator. The input voltage is from 5.5V to
16V. The output voltage is programmable from 0.6V to
5V. DC2268A-B can deliver up to 13A maximum in each
channel. As explained in the data sheet, output current
derating is necessary for certain V
IN
, V
OUT
, and thermal
conditions. The board operates in continuous conduction
mode in heavy load conditions. For high efficiency at low
load currents, the resistor jumper (R1/R2) selects pulse-
skipping mode for noise sensitive applications or Burst
Mode
®
in less noise sensitive applications. Two outputs can
be connected in parallel for a single 26A output solution
with optional jumper resistors. The board allows the user
to program how its output ramps up and down through
the TRACK/SS pin. Remote output voltage sensing is
available for improved output voltage regulation at the load
point. An optional input inductor L1 reduces the EMI noise
for noise sensitive applications. DC2268A can be easily
inserted to an edge connector for testing and debugging.
These features and the availability of the LTM4620A in a
compact 16mm × 16mm × 5.01mm BGA package make
it ideal for use in many high-density point-of-load regula-
tion applications. The LTM4620A data sheet must be read
in conjunction with this demo manual for working on or
modifying the demo circuit DC2268A-B.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2268A-B
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
Figure 1. LTM4620A/DC2268A-B Demo Board
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DEMO MANUAL DC2268A-B
performance summary
PARAMETER
Input Voltage Range
Output Voltage V
OUT1
Output Voltage V
OUT2
Per-Channel Maximum Continuous Output Current
Default Operating Frequency
Resistor Programmable Frequency Range
External Clock Sync. Frequency Range
Efficiency of Channel 1
Efficiency of Channel 2
Load Transient of Channel 1
Load Transient of Channel 2
V
IN
= 12V, V
OUT2
= 3.3V, I
OUT2
= 13A, f
SW
= 750kHz
V
IN
= 12V, V
OUT1
= 5V, I
OUT1
= 13A, f
SW
= 750kHz
V
IN
= 12V, V
OUT2
= 3.3V, I
STEP
= 6.5A ~ 13A
V
IN
= 12V, V
OUT1
= 5V, I
STEP
= 6.5A ~ 13A
V
IN
= 4.5V ~ 15V, I
OUT1
= 0A ~ 13A
V
IN
= 4.5V ~ 15V, I
OUT2
= 0A ~ 13A
Derating Is Necessary for Certain V
IN
, V
OUT
and Thermal
Conditions.
Specifications are at T
A
= 25°C
VALUE
5.5V ~ 16V
3.3V ±1.5%
1.5V ±1.5%
13A
750kHz
250kHz to 780kHz
400kHz to 780kHz
91.8% See Figure 3
93.9% See Figure 4
See Figure 5
See Figure 6
CONDITIONS
Quick start proceDure
Demonstration circuit DC2268A-B is easy to set up to
evaluate the performance of the LTM4620A. It can be
easily inserted to an edge connector (SAMTEC MEC2-
20-01-L-DV--TR) for testing and debugging. Please refer
to Figure 2 for proper measurement setup and follow the
procedure below:
1. Pull up the RUN1 (J1 pin 22) and RUN2 (J1 pin 24)
between 1.4V to 5V or leave them floating.
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 in channel 1 should be 3.3V ± 1.5% (3.2505V ~
3.3495V) and the output voltage in channel 2 should
be 5V ± 1.5% (4.925V ~ 5.075V),
4. Once the proper output voltage is established, adjust the
load within the operating range and observe the output
voltage regulation, output voltage ripple, efficiency and
other parameters. Output ripple should be measured
at Co3 and Co4.
5. (Optional) LTM4620A can be synchronized to an exter-
nal clock signal. Remove R2 and apply a clock signal
(0~5V, square wave) to MODE-PLLIN pin.
6. (Optional) LTM4620A can be configured for a 2-phase
single output at up to 36A on DC2268A-B. Install 0Ω
resistors on R26, R27, R28, R29, R32, and remove
R14, R18, R30. Output voltage is set by R7 based on
equation V
OUT
= 0.6V(1 + 60.4k/R7).
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DEMO MANUAL DC2268A-B
Quick start proceDure
Table 2. DC2268A Demo Circuit
DEMO BOARD NUMBER
DC2268A-A
DC2268A-B
DC2268A-C
DC2268A-D
DC2268A-E
DC2268A-F
DC2268A-G
µMODULE REGULATOR ON THE BOARD
LTM4620
LTM4620A
LTM4628
LTM4630
LTM4630-1
LTM4630A
LTM4631
OUTPUT CURRENT
13A,13A
13A,13A
8A, 8A
18A,18A
18A,18A
18A, 18A
10A, 10A
Figure 2. Test Setup of DC2268A-B
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DEMO MANUAL DC2268A-B
Quick start proceDure
Efficiency, 3.3V
100
V
IN
= 12V
f
SW
= 750kHz
91.6
90.4
91.8
89.1
91.1
87.5
85
84.6
92 92 92 91.9
91.8
100
Efficiency, 5V
95
EFFICICENCY (%)
EFFICICENCY (%)
95
91.4
90
90.2
87
85
92.4
93
93.5 93.9 94 94 94
93.9
93.7
90
80
75.2
0 1 2 3 4 5 6 7 8 9 10 11 12 13
I
LOAD
(A)
dc2268ab F03
80
77.4
75
V
IN
= 12V
f
SW
= 750kHz
75
0 1 2 3 4 5 6 7 8 9 10 11 12 13
I
LOAD
(A)
dc2268ab F04
Figure 3. Measured Efficiency on Channel 1
(V
OUT1
= 3.3V, f
SW
= 750kHz, Channel 2 Disabled)
Figure 4. Measured Efficiency on Channel 2
(V
OUT2
= 5V, f
SW
= 750kHz, Channel 1 Disabled)
3.3V OUTPUT (20MHz BW) [20mV/DIV]
6.5A TO 13A LOAD STEP
dc2268ab F05
Figure 5. Measured Channel 6.5A to 13A Load Transient (V
IN
= 12V, V
OUT1
= 3.3V)
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DEMO MANUAL DC2268A-B
Quick start proceDure
5V OUTPUT (20MHz BW) [20mV/DIV]
6.5A TO 13A LOAD STEP
dc2268ab F06
Figure 6. Measured Channel 2 6.5A to 13A Load Transient (V
IN
= 12V, V
OUT2
= 5V)
Figure 7. Thermal Performance at V
IN
= 12V, V
OUT1
= 3.3V/8A,
V
OUT2
= 5V/8A, f
SW
= 750kHz, T
A
= 23°C, 200LFM Airflow
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