DC1725A - Demo Manual

DEMO MANUAL DC1725A
LT3759
Wide Input Voltage Range
Boost/SEPIC/Inverting Controller
DESCRIPTION
The LT3759 is a current mode DC/DC controller operating
over an input range of 1.6V to 42V, making it well suited
for applications ranging from single-cell lithium-ion battery portable electronics to high voltage automotive and
industrial power supplies. It also exhibits low shutdown
quiescent current of 1μA, making it an ideal fit for battery
operated systems. Thanks to a novel FBX pin architecture,
the LT3759 can be connected directly to a divider from
either a positive or negative output feedback voltage to
ground. It also packs many popular features such as softstart, input undervoltage lockout, adjustable frequency and
synchronization in a small 12-lead exposed pad MSOP
package.
Demonstration circuit 1725A features LT3759 in a 485kHz
boost converter, designed for a 5V/2A output from a 1.8V
to 4.5V input. The demo circuit configures the shutdown
voltage at typical 1.70V, which means that the input voltage can be dropped to as low as 1.70V, once it starts up.
The start-up voltage is set at 2.5V but can be adjusted by
changing R1 and R2 values.
The LT3759 data sheet gives a complete description of the
part, operation and application information. The data sheet
must be read in conjunction with this quick start guide.
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
(TA = 25°C)
PARAMETER
CONDITIONS
MIN
Input Voltage Range, VIN
IOUT = 0mA~2A
1.8
TYP
Minimum Start-up Voltage
MAX
UNITS
4.5
V
2.5
V
Switching Frequency
IOUT = 2A
485
Output Voltage, VOUT
VIN = 1.8V~4.5V
IOUT = 0mA~2A
4.85
Maximum Continuous Output Current, IOUT
VIN = 1.8V~4.5V
2.0
Output Voltage Ripple
VIN = 2.5V, IOUT = 2A
60
mV
Typical Efficiency
VIN = 4.5V, IOUT = 2A
90
%
5.0
kHz
5.15
V
A
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DEMO MANUAL DC1725A
QUICK START PROCEDURE
Demo circuit 1725A is easy to set up to evaluate the performance of LT3759. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below.
NOTE: Make sure that the input voltage does not exceed
4.5V. If higher operating voltage is required, power
components with higher voltage ratings should be used.
1. With power off, connect the input power supply, load
and meters as shown in Figure 1. Preset the load to 0A,
and VIN supply to be 0V. Place jumpers in the following
positions for a typical 5V application:
3. Once the proper output voltage is established, adjust
the input voltage and load within the operating range
and observe the output voltage regulation, ripple voltage, efficiency and other parameters. Typical efficiency
curve is shown in Figure 3.
EN (JP1)
ON
SYNC (JP2)
OFF
2. Turn on VIN and increase slowly to 2.5V. Check for proper
output voltages. The output should be regulated at 5V
(±3%). The switching frequency should be about 485kHz.
NOTE: If there is no output, or the output is out of spec,
temporarily disconnect the load to make sure that the
load is not set too high, and the power supply current
capability is above 7A. Minimize voltage drop over the
input wires.
NOTE: When measuring the input or output voltage
ripples, care must be taken to avoid a long ground
lead on the oscilloscope probe. Measure the input or
output voltage ripple by touching the probe tip directly
across the VIN and GND, or VOUT and GND terminals.
See Figure 2 for proper scope probe technique.
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DEMO MANUAL DC1725A
QUICK START PROCEDURE
dc1725a F01
Figure 1. Proper Measurement Equipment Setup
100
90
EFFICIENCY (%)
80
70
60
50
40
30
20
VIN = 1.8V
VIN = 2.5V
VIN = 4.5V
10
0
0
INPUT OR OUTPUT CAPACITOR
dc1725a F01
200
400
600
800
1200
1600
2000
1000
1400
1800
LOAD CURRENT (mA)
dc1725a F03
Figure 2. Proper Scope Probe Placement for
Measuring Input or Output Ripple
Figure 3. Efficiency with Different Input Voltages
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DEMO MANUAL DC1725A
PARTS LIST
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Required Circuit Components
1
4
CO1, CIN1, CO2, CIN2
CAP, 1210, 100μF, 20%, 6.3V, X5R
MURATA GRM32ER60J107ME20L
2
1
CIN3
CAP, 270μF, 20%, 10V
SANYO 10SVPC270M
3
1
C1
CAP, 1206, 4.7μF, 10%, 50V, X5R
TAIYO YUDEN UMK316BJ475KL
4
1
C2
CAP, 0402, 0.1μF, 10%, 16V, X5R
AVX 0402YD104KAT2A
5
1
C3
CAP, 0402, 22nF, 10%, 25V, X7R
MURATA GRM155R71E223KA61D
6
1
C4
CAP, 0402, 120pF, 10% 25V, X7R
AVX 04023C121KAT2A
7
1
D1
DIODE, SCHOTTKY BARRIER RECTIFIER SMA
DIODES INC/ZETEX SBR3U20SA
8
1
L1
IND, 2.2μH
WÜRTH ELEKTRONIK 7443552200
9
1
Q1
XSTR, N-CHANNEL MOSFET
VISHAY Si7858ADP-T1-E3
10
1
RCS1
RES, 0815 0.005Ω, 1% 1W
SUSUMU/THIN FILM RL3720WT-R005-F
11
1
RFBA
RES, 0402, 34kΩ, 1%, 1/16W
VISHAY CRCW040234K0FKED
12
1
RFBB
RES, 0402, 15.8kΩ, 1%, 1/16W
VISHAY CRCW040215K8FKED
13
1
R1
RES, 0402, 348kΩ, 1%, 1/16W
VISHAY CRCW0402348KFKED
14
1
R2
RES, 0402, 887kΩ, 1%, 1/16W
VISHAY CRCW0402887KFKED
15
1
R3
RES, 0402, 5.1kΩ, 1%, 1/16W
VISHAY CRCW04025K10FKED
16
1
R4
RES, 0402, 16.9kΩ, 1%, 1/16W
VISHAY CRCW040216K9FKED
17
1
R5
RES, 0402, 100kΩ, 1%, 1/16W
VISHAY CRCW0402100KFKED
18
1
U1
IC, INVERTING CONVERTER
LINEAR TECH. LT3759EMSE
Hardware/Components (For Demo Board Only)
1
7
E1-E7
TURRETS
MILLMAX 2501-2-00-80-00-00-07-0
2
2
JP1, JP2
HEADER, 3-PIN, 2mm
SAMTEC TMM-103-02-L-S
3
2
J1, J2
JACK, BANANA
KEYSTONE 575-4
4
2
JP1, JP2
SHUNT, 2mm
SAMTEC 2SN-BK-G
5
4
MH1, MH2, MH3, MH4
STANDOFF, SNAP ON
KEYSTONE 8834
6
1
FAB, PRINTED CIRCUIT BOARD
DEMO CIRCUIT 1725A
7
1
STENCIL FOR BOTH SIDES
STENCIL 1725A
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DEMO MANUAL DC1725A
SCHEMATIC DIAGRAM
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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.
5
DEMO MANUAL DC1725A
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
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Linear Technology Corporation
LT 1011 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2011
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