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
, V
derating is necessary for certain V
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 pulseskipping mode for noise sensitive applications or Burst
®
Mode
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
in less noise sensitive applications. Tw o outputs can
IN
, and thermal
OUT
BoarD photo
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
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.
The LTM4620A data sheet must be read
-
Figure 1. LTM4620A/DC2268A-B Demo Board
dc2268abfa
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DEMO MANUAL DC2268A-B
performance summary
PARAMETERCONDITIONSVALUE
Input Voltage Range5.5V ~ 16V
Output Voltage V
Output Voltage V
Per-Channel Maximum Continuous Output Current Derating Is Necessary for Certain V
Default Operating Frequency750kHz
Resistor Programmable Frequency Range250kHz to 780kHz
External Clock Sync. Frequency Range400kHz to 780kHz
Efficiency of Channel 1V
Efficiency of Channel 2V
Load Transient of Channel 1V
Load Transient of Channel 2V
VIN = 4.5V ~ 15V, I
OUT1
VIN = 4.5V ~ 15V, I
OUT2
Specifications are at TA = 25°C
= 0A ~ 13A3.3V ±1.5%
OUT1
= 0A ~ 13A1.5V ±1.5%
OUT2
Conditions.
= 12V, V
IN
= 12V, V
IN
= 12V, V
IN
= 12V, V
IN
OUT2
OUT1
OUT2
OUT1
= 3.3V, I
= 5V, I
OUT1
= 3.3V, I
= 5V, I
STEP
OUT2
STEP
, V
and Thermal
IN
OUT
= 13A, fSW = 750kHz91.8% See Figure 3
= 13A, fSW = 750kHz93.9% See Figure 4
= 6.5A ~ 13A See Figure 5
= 6.5A ~ 13A See Figure 6
13A
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 MEC220-01-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.
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.
-
2. With power off, connect the input power supply, load
and meters as shown in Figure 1. Preset the load to 0A
and V
supply to 12V.
IN
3. Turn on the power supply at the input. The output volt-
channel 1 should be 3.3V ± 1.5% (3.2505V ~
age in
3.3495V)
and the output voltage in channel 2 should
be 5V ± 1.5% (4.925V ~ 5.075V),
2
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
= 0.6V(1 + 60.4k/R7).
OUT
dc2268abfa
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DEMO MANUAL DC2268A-B
Quick start proceDure
Table 2. DC2268A Demo Circuit
DEMO BOARD NUMBERµMODULE REGULATOR ON THE BOARDOUTPUT CURRENT
DC2268A-ALTM462013A,13A
DC2268A-BLTM4620A13A,13A
DC2268A-CLTM46288A, 8A
DC2268A-DLTM463018A,18A
DC2268A-ELTM4630-118A,18A
DC2268A-FLTM4630A18A, 18A
DC2268A-GLTM463110A, 10A
Figure 2. Test Setup of DC2268A-B
dc2268abfa
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DEMO MANUAL DC2268A-B
dc2268ab F05
EFFICICENCY (%)
100
dc2268ab F03
13
100
13
EFFICICENCY (%)
dc2268ab F04
Quick start proceDure
Efficiency, 3.3VEfficiency, 5V
VIN = 12V
= 750kHz
f
SW
95
90.4
84.6
87.5
89.1
91.1
90
85
91.6
91.8
92 92
92
91.9
91.8
949394
95
90
87
85
90.2
91.4
92.4
93.5
93.9
93.7
94
93.9
80
75.2
75
0
62107311519
I
(A)
LOAD
8412
Figure 3. Measured Efficiency on Channel 1
(V
= 3.3V, fSW = 750kHz, Channel 2 Disabled)
OUT1
3.3V OUTPUT (20MHz BW) [20mV/DIV]
80
77.4
75
0
62107311519
I
LOAD
VIN = 12V
f
SW
8412
(A)
= 750kHz
Figure 4. Measured Efficiency on Channel 2
(V
= 5V, fSW = 750kHz, Channel 1 Disabled)
OUT2
4
Figure 5. Measured Channel 6.5A to 13A Load Transient (VIN = 12V, V
6.5A TO 13A LOAD STEP
OUT1
= 3.3V)
dc2268abfa
Page 5
dc2268ab F06
Quick start proceDure
5V OUTPUT (20MHz BW) [20mV/DIV]
DEMO MANUAL DC2268A-B
6.5A TO 13A LOAD STEP
Figure 6. Measured Channel 2 6.5A to 13A Load Transient (VIN = 12V, V
Figure 7. Thermal Performance at VIN = 12V, V
V
= 5V/8A, fSW = 750kHz, TA = 23°C, 200LFM Airflow
OUT2
= 3.3V/8A,
OUT1
OUT2
= 5V)
dc2268abfa
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DEMO MANUAL DC2268A-B
parts List
ITEMQTYREFERENCEPART DESCRIPTIONMANUFACTURER/PART NUMBER
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
3
4
5
dc2268abfa
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.
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DEMO MANUAL DC2268A-B
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 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. 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.
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 LTC application engineer.