DC1270A -Demo Manual

DEMO MANUAL DC1270A
LTC3852EUDD
Low VIN, High Efficiency
Step-Down DC/DC Converter
DESCRIPTION
Demonstration circuit 1270A is a low input voltage, high
efficiency synchronous buck DC/DC converter with 2.7V to
5.5V input range. It can supply 15A maximum load current at
1.5V output. The demo board features the LTC®3852EUDD
controller. The integrated charge pump provides 5V to
the LTC3852’s control logic and gate drives, supporting a
wide selection of logic-level N-channel power MOSFETs
with high efficiency. The constant frequency current mode
architecture allows a phase-lockable frequency of up to
750kHz. The LTC3852 is ideal for general purpose 3.3V
systems, lithium-ion powered devices and distributed DC
power systems. The LTC3852EUDD is in a 3mm × 5mm
24-Lead QFN package.
The light load operation mode of the converter is determined with the FCB pin. Use JP2 jumper to select burst
mode, discontinuous mode or forced continuous mode
operation. Switching frequency is preset at about 400KHz.
This frequency can be easily modified from 250kHz to
750kHz by changing the value of a resistor (R5). The converter can also be externally synchronized from 250kHz to
750kHz through MODE/PLLIN pin (PLLIN terminal on the
board). To shut down the converter, one simple way is to
force the RUN pin below 1.1V (JP1: OFF). The power good
output (PGOOD terminal) is low when the output voltage
exceeds the ±10% regulation window.
Design files for this circuit board are available at
http://www.linear.com/demo
L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear
Technology Corporation. All other trademarks are the property of their respective owners.
PERFORMANCE SUMMARY
PARAMETER
(TA = 25°C)
CONDITION
Input Voltage Range
VALUE
2.7V to 5.5V
VIN = 2.7V to 5.5V, IOUT = 0A to 15A
1.5V ±2%
Maximum Output Current, IOUT
VIN = 2.7V to 5.5V, VOUT = 1.5V
15A
Typical Output Ripple
VIN = 3.3V, IOUT = 15A (20MHz BW)
11mVP-P
Typical Efficiency
VIN = 3.3V, VOUT = 1.5V, IOUT = 15A
90.4%
Output Voltage, VOUT
Typical Switching Frequency
400kHz
dc1270Af
1
DEMO MANUAL DC1270A
QUICK START PROCEDURE
Demonstration circuit 1270A is easy to set up to evaluate
the performance of the LTC3852EUDD. Refer to Figure 1
for the proper measurement equipment setup and follow
the procedure below:
1. With power off, connect the input power supply to
VIN(2.7V to 5.5V) and GND (input return).
2. Connect the 1.5V output load between VOUT and GND
(Initial load: no load).
3. Connect the DVMs to the input and outputs.
4. Turn on the input power supply and check for the proper
output voltages. VOUT should be 1.5V ±2%.
5. Once the proper output voltages are established, adjust
the loads within the operating range and observe the
output voltage regulation, ripple voltage and other
parameters.
Note: When measuring the output or input voltage ripple,
do not use the long ground lead on the oscilloscope probe.
See Figure 2 for the proper scope probe technique. Short,
stiff leads need to be soldered to the (+) and (–) terminals
of an output capacitor. The probe’s ground ring needs to
touch the (–) lead and the probe tip needs to touch the
(+) lead.
OPTIONAL HIGH INPUT VOLTAGE (4V to 38V)
OPERATION
The LTC3852 can also be used for high input voltage applications (4V to 38V input), with the integrated charge
pump bypassed:
1. Remove the 0Ω resistor from R3 and put the resistor
at R26 position (disconnect VIN1 from VIN , and connect
VIN2 from VIN). Remove R22 and R23. The C1 flying
cap can also be removed.
2. The related power components, such as input/output
capacitors, MOSFETs, and inductor, need to be changed
to fit the new application specification.
1270A F01
Figure 1. Proper Measurement Equipment Setup
dc1270Af
2
DEMO MANUAL DC1270A
QUICK START PROCEDURE
+
_
COUT
VOUT
GND
1270A F02
Figure 2. Measuring Output Voltage Ripple
100
90
EFFICIENCY (%)
80
BM
PS
CCM
70
60
50
40
VIN = 3.3V
VOUT = 1.5V
IOUT = 15A_MAX
FSW = 400kHz
QTOP = 1 × SIR438DP
QBOT = 1 × SIR438DP
30
20
10
0
0.01
0.10
10
1.0
LOAD CURRENT (A)
100
3060 TA02
Figure 3. Efficiency vs Load Current
PARTS LIST
ITEM
REFERENCEDESCRIPTION
QUANTITY
DESCRIPTION
MANUFACTURERS PART NUMBER
Required Circuit Components
1
2
CIN2, CIN1
Cap., POSCAP 220μF 6.3V 20% 7343
SANYO 6TPE220MI
2
2
CIN6, CIN5
Cap., X5R 10μF 16V 20% 1206
Taiyo Yuden EMK316BJ106ML
3
1
COUT1
Cap., X5R 100μF 6.3V 20% 1210
AVX 12106D107MAT2A
4
2
COUT3, COUT4
Cap., POSCAP 330μF 4V 20%
SANYO 4TPE330MI
5
1
C1
Cap., X5R 2.2μF 10V 10% 0603
Taiyo Yuden LMK107BJ225MA
6
4
C2, C7, C14, C15
Cap., X5R 4.7μF 10V 10% 0603
Taiyo Yuden LMK107BJ475KA
7
1
C3
Cap., X7R 100pF 25V 10% 0603
AVX 06033C101KAT2A
8
1
C4
Cap., X7R 0.01μF 100V 10% 0603
AVX 06031C103KAT2A
9
3
C5, C6, C11
Cap., X7R 0.1μF 25V 10% 0603
AVX 06033C104KAT2A
10
1
C8
Cap., X7R 2200pF 25V 20% 0603
AVX 06033C222MAT2A
11
1
C9
Cap., X7R 150pF 25V 10% 0603
AVX 06033C151KAT1A
12
2
C12, C16
Cap., NPO 1000pF 25V 10% 0603
AVX 06033A102KAT1A
13
1
D1
Schottky Diode, 30V
Central Semi. CMDSH-3
14
1
L1
Inductor, 0.4uH
Vitec 59PR9875N
dc1270Af
3
DEMO MANUAL DC1270A
PARTS LIST
ITEM
QUANTITY
15
2
REFERENCEDESCRIPTION
DESCRIPTION
MANUFACTURERS PART NUMBER
Q1,mQ3
Mosfet-N Channel, 30V/45A LFPAK
Renesas RJK0330DPB-00-J0
Q1,mQ3 (Alternate)
Mosfet-N Channel, Reduced Qg, 25V SO-8
Vishay SiliconixSiR438DP
16
1
RS1
Res., 0.002 1/2W 1% 2010
Vishay WSL-2010-2L000-F-EA
17
3
R1, R16, R17
Res., Chip 100k 0.06W 5% 0603
Vishay CRCW0603104JNEA
18
1
R2
Res., Chip 10 0.06W 5% 0603
Vishay CRCW0603100JNEA
19
8
R3, R6, R10, R13,
R22-R25
Res/Jumper, Chip 0Ω 1/16W 1 AMP 0603
Vishay CRCW0603000ZOEA
20
1
R5
Res., Chip 82.5k 0.06W 1% 0603
Vishay CRCW060382K5FKEA
21
1
R7
Res., Chip 1k 0.06W 5% 0603
Vishay CRCW06031K00JNEA
22
1
R9
Res., Chip 5.90k 0.06W 1% 0603
Vishay CRCW06035K90FKEA
23
2
R12, R11
Res., Chip 100 0.06W 5% 0603
Vishay CRCW0603100RJNEA
24
1
R19
Res., Chip 20k 0.06W 1% 0603
Vishay CRCW06032002FKEA
25
1
R20
Res., Chip 17.4k 0.06W 1% 0603
Vishay CRCW06031742FKEA
26
1
R21
Res/Jumper, Chip 0Ω 1/8W 1 AMP 0805
Vishay CRCW08050000ZOEA
27
1
U1
I.C., Volt. Reg. QFN(24)(UDD) 3mm × 5mm
Linear Tech. Corp. LTC3852EUDD
Additional Circuit Components
1
0
CIN3, CIN4
Cap., POSCAP 220μF 6.3V 20% 7343
Sanyo 6TPE220MI
2
0
COUT2
Cap., X5R 100μF 6.3V 20% 1210
AVX 12106D107MAT2A
Sanyo 4TPE330MI
3
0
COUT5, COUT6
Cap., POSCAP 330μF 4V 20%
4
0
C13
Cap., 0603
5
0
Q4, Q2
N-Chan. Single, SO8-PWRPAK-SGL
6
0
R8, R14, R15, R26
Res., 0603
Hardware For Demo Board Only
1
9
E1-E4, E6 to E10
Turret, Testpoint
Mill Max 2501-2-00-80-00-00-07-0
2
2
JP3, JP1
Headers, 3 Pins 2mm Ctrs.
Samtec TMM-103-02-L-S
3
1
JP2
Headers, 4 Pins 2mm Ctrs.
Samtec TMM-104-02-L-S
4
4
J1-J4
Connector, Banana Jack
Keystone 575-4
5
3
XJP1 to XJP3
Shunt, 2mm Ctrs.
Samtec 2SN-BK-G
6
4
Stand-Off, Nylon 0.5" Tall
Keystone, 8833(Snap On)
7
1
FAB, Rev3 Printed Circuit Board
Demo Circuit 1270A
8
2
Stencil
Stencil #1270A
dc1270Af
4
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.
A
JP2
PGOOD
TRACK
OFF
ON
RUN
EXTCLK
E9
E8
JP1
RUN
E6
JP3
3
2
1
3
FREQ/PLLFLTR
1
400K
2
4
3
5
C5
100K
1K
R7
C4
C8
2200pF
0.01uF
1000pF
C16
82.5K
1%
0.1uF
R5
0 Ohm
R13
INTVCC
100K
R16
R9
0 Ohm
R25
VIN
5.90K
100K
R17
C11
0.1uF
C9
150pF
10
3
22
21
23
20
19
SHDN
PGOOD
TRACK/SS
RUN
ITH
220uF
6.3V
CIN3
(OPT)
CIN4
(OPT)
C-
12
4
11
25
4
6
9
FB
SENSE-
SENSE+
BG
INTVCC
VIN2
VPUMP
BOOST
SW
TG
VIN1
24
1
2
13
C7
4.7uF
10V
15 VIN2
C14
4.7uF
10V
14 INTVCC
C15
4.7uF
10V
5
16
18
VIN
VIN+
E2
17
4.7uF
10V
C2
R3
0 Ohm
GND1 GND GND2 NC NC
U1
LTC3852EUDD
FREQ/PLLFLTR
C1
CIN2
220uF
6.3V
J2
VIN
2.7V TO 5.5V
CIN1
2.2uF
10V
7 0603 8
MODE/PLLIN C+
C3
100pF
R2
10
GND
+
E3
PLLIN
PS
1
2
J1
+
B
CCM
R1
VIN-
+
BURST
MODE
E1
4
+
C
D
5
R22
R20
17.4K
1%
R14
(OPT)
0 Ohm
R10
0 Ohm
R24
C12
1000pF
R19
20K
1%
0 Ohm
0 Ohm
R23
0 Ohm
R6
(OPT)
C13
3
0 Ohm
0805
R21
Q3
D1
CMDSH-3
0.1uF
C6
Q1
3
CIN5
10uF
16V
1206
R15
(OPT)
59PR9875N
Vitec
L1
0.4uH
NOTE:
ECO
3
REV
DESCRIPTION
PRODUCTION
RS1
R11
100
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
2
COUT2
(OPT)
+
DATE:
N/A
SIZE
APPROVED
J3
E4
R26
(Opt)
TECHNOLOGY
VIN
E10
VIN2
VOUT-
GND
DATE
08/23/10
IC NO.
Tuesday, November 02, 2010
1
SHEET 1
OF
1
LOW VIN, HIGH EFFICIENCY STEP-DOWN
DC/DC CONVERTER
REV.
LTC3852EUDD
3
DEMO CIRCUIT 1270A
1630 McCarthy Blvd.
Milpitas, CA 95035 www.linear.com
Phone: (408)432-1900
Fax: (408)434-0507
VIN2
E7
VOUT
1.5V / 15A
VOUT+
CHARLIE Z.
COUT3
COUT4 COUT5 COUT6
+
+
+
330uF
330uF
(OPT)
(OPT)
4V
4V
J4
CHARLIE Z. TITLE: SCHEMATIC
RB
SCALE = NONE
APP ENG.
PCB DES.
APPROVALS
R12
100
COUT1
100uF
6.3V
2. WHEN DCR SENSING IS IMPLEMENTED, SHORT RS1
AND DO NOT POPULATE R11 AND R12.
0.002
1%
1
REVISION HISTORY
1. WHEN RESISTOR SENSING IS IMPLEMENTED DO NOT
POPULATE R8 AND R15.
CUSTOMER NOTICE
Q4
(OPT)
R8
(OPT)
Q2
(OPT)
CIN6
10uF
16V
1206
2
A
B
C
D
DEMO MANUAL DC1270A
SCHEMATIC DIAGRAM
dc1270Af
5
DEMO MANUAL DC1270A
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 LTC 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 LTC 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.
LTC 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.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
dc1270Af
6
Linear Technology Corporation
LT 1210 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2010
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