DC2172A - Demo Manual

DEMO MANUAL DC2172A
LTC7138
High Efficiency, High VIN,
Step-Down Regulator
Description
Demonstration circuit 2172A is a high input voltage, 400mA
step-down regulator featuring the LTC7138. The output of
the regulator can be programmed for either 5V, 3.3V or
1.8V with on-board jumpers or is adjustable from 800mV
to VIN using an optional feedback divider. The input voltage
range is from 4V to 140V. The LTC7138’s Burst Mode®
operation, low quiescent current and internal top FET
switch provide high efficiency over a wide range of loads.
Other features include:
• Optional components to adjust the current limit, make it
proportional to VIN or improve the efficiency and reduce
the output voltage ripple.
• FBO turret to tie two or more LTC7138 regulators together if the application requires more load current.
• Optional UVLO and OVLO divider.
• External/internal soft-start.
For more details, refer to the LTC7138 data sheet. The
LTC7138 data sheet gives a complete description of the
IC 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/DC2172A
L, LT, LTC, LTM, Burst Mode, 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
Specifications are at TA = 25°C
PARAMETER
CONDITIONS
Input Voltage Range
VALUE
4V to 140V
5.0V Output Voltage
VIN = 12V, IOUT = 0mA to 400mA
5.0V ±2%
3.3V Output Voltage
VIN = 12V, IOUT = 0mA to 400mA
3.3V ±2%
1.8V Output Voltage
VIN = 12V, IOUT = 0mA to 400mA
1.8V ±2%
Maximum Output Current, IOUT
VIN = 4V to 140V, VOUT = 5.0, 3.3V, 1.8V or ADJ (VOUT ≤ VIN)
400mA
Typical Efficiency
VIN = 12V, VOUT = 5V, IOUT = 400mA
82.3%
Typical Output Ripple
VIN = 12V, VOUT = 5V, IOUT = 400mA
87mVP-P
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1
DEMO MANUAL DC2172A
Quick Start Procedure
Demonstration circuit 2172A is easy to set up to evaluate
the performance of the LTC7138. Please refer to Figure 1
for proper measurement equipment setup and follow the
procedure below.
Note 1. CAUTION: The maximum input voltage of the
DC2172A is 140V. Voltages of 140V or lower are high
enough to cause electric shock. Use great care when
testing this demo board.
1)With power off, connect the input supply, load and
meters as shown in Figure 1. Preset the load to 0A and
VIN supply to 0V.
Note 2. For a 5V output, the input voltage should be 6V
or more.
2)Place the RUN pin jumper (JP3) in the ON position.
3)Set the output to 5V by placing the JP1 jumper in the
B position and the JP2 jumper in the A position.
4)Turn-on the VIN supply and increase to 12V. The 5V
output should be 5V ±2% per the Performance Summary table.
Note 3. 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.
5)Next, apply 400mA load to the output and re-measure
VOUT.
6)Once the DC regulation is confirmed, observe the output
voltage ripple, load step response, efficiency and other
parameters for the 5V, 3.3V and 1.8V output settings.
2
dc2172af
DEMO MANUAL DC2172A
Quick Start Procedure
IIN
IOUT
+
VIN
SUPPLY
VOUT
LOAD
+
–
–
Figure 1. Proper Measurement Equipment Setup
+
VOUT
–
COUT
GND
Figure 2. Measuring Output Voltage Ripple
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3
DEMO MANUAL DC2172A
Quick Start Procedure
90
80
70
L = Sumida CDRH105RNP-151NC
(150µH, DCR = 285mΩ typ)
VOUT = 5V
Efficiency (%)
60
50
40
30
20
12VIN
48VIN
100VIN
140VIN
10
0
0.01
0.10
1
10
Load Current (mA)
100
1,000
dc2172a F03
Figure 3. Efficiency at 5VOUT
80
70
L = Sumida CDRH105RNP-151NC
(150µH, DCR = 285mΩ typ)
VOUT = 3.3V
Efficiency (%)
60
50
40
30
20
12VIN
48VIN
100VIN
140VIN
10
0
0.01
0.10
1
10
Load Current (mA)
100
1,000
dc2172a F04
Figure 4. Efficiency at 3.3VOUT
4
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DEMO MANUAL DC2172A
Quick Start Procedure
70
60
L = Sumida CDRH105RNP-151NC
(150µH, DCR = 285mΩ typ)
VOUT = 1.8V
Efficiency (%)
50
40
30
20
12VIN
48VIN
100VIN
140VIN
10
0
0.01
0.10
1
10
Load Current (mA)
100
1,000
dc2172a F05
Figure 5. Efficiency at 1.8VOUT
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5
DEMO MANUAL DC2172A
Parts List
ITEM
QTY
REFERENCE
PART DESCRIPTION
MANUFACTURER/PART NUMBER
Required Circuit Components
1
1
C1
CAP 22µF, 200V, ELEC
NIPPON CHEMI-CON, EMVE201ARA220MKG5S
2
1
C2
CAP 1µF, 2220, 10%, 200V, X7R
KEMET C2220X105K2RACTU
3
1
C4
CAP 47nF, 0603, 10%, 25V, X7R
AVX 06033C473KAT2A
4
2
C6, C7
CAP 100µF, 1210, 20%, 10V, X7R
TAIYO YUDEN LMK325ABJ107MMH-T
5
1
C9
CAP 0.1µF, 0603, 10%, 25V, X7R
AVX 06033C104KAT2A
6
1
D1
DIODE SBR1U200P1
DIODES, SBR1U200P1-7
7
1
L1
INDUCTOR 150µH
SUMIDA CDRH105RNP-151NC
8
1
R1
RES 2M, 0603Ω, 5%, 1/10W
VISHAY CRCW06032M00JNEA
9
1
U1
IC LTC7138EMSE
LINEAR TECH LTC7138EMSE#PBF
Additional Demo Board Circuit Components
1
0
C3
CAP 0603 OPTION
OPTION
2
0
C8, C10
CAP 1210 OPTION
OPTION
3
0
R2, R4, R7, R8
RES 0603 OPTION
OPTION
4
2
R3, R6
RES 0Ω 0603 JUMPER
VISHAY CRCW06030000Z0ED
1
5
E1, E2, E3, E4, E5
TURRET
MILL-MAX 2501-2-00-80-00-00-07-0
2
3
JP1, JP2, JP3
HEADER 2mm PIN
SULLINS, NRPN031PAEN-RC
3
4
MH1, MH2, MH3, MH4
STANDOFF SNAP ON
KEYSTONE_8831
4
3
JP1, JP2, JP3
SHUNT 2mm
SAMTEC 2SN-BK-G
Hardware
6
dc2172af
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
B
C
D
E5
C1
22uF +
200V
VIN
R3
0
R2
OPT
R1
2M
VIN
ON
1
RUN
OPT
R8
2
[3]
B
A
5.0V
EXT. R
5
B
A
3.3V
JP1
1.8V
VOUT
A
A
B
B
JP2
3
11
5
12
14
C3
OPT
C2
1uF
200V
2220
ISET
FBO
OVLO
RUN
VIN
SW
3
6
7
10
9
16
1
4
3
THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
L1 150uH
APPROVALS
SCALE = NONE
1
2
3
1
2
3
JP2
[3]
JP1
[3]
A
B
A
B
2
DATE:
N/A
SIZE
VOUT
C8
C10
OPT
1210
2
E3
GND
VOUT
C9
1.8V
/ 3.3V / 5V
0.1uF
400mA
E2
1
SHEET 1
HIGH EFFICIENCY, HIGH VIN, 400mA
STEP-DOWN REGULATOR
LTC7138EMSE
DEMO CIRCUIT 2172A
TECHNOLOGY
2
OF 1
RE V .
1630 McCarthy Blvd.
Milpitas, CA 95035
Phone: (408)432-1900 www.linear.com
Fax: (408)434-0507
LTC Confidential-For Customer Use Only
Tuesday, January 06, 2015
IC NO.
C6
C7
100uF
10V
1210
1
4. SMALLER AMOUNT OF COUT CAN BE USED
FOR APPLICATIONS THAT CAN TOLERATE
HIGHER OUPUT RIPPLE.
REFER TO THE DATA SHEET FOR
APPLICATIONS INFORMATION.
R7
OPT
R6
0
TITLE: SCHEMATIC
D1
SBR1U200P1
CDRH105R
C4
47nF
LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A
CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS;
HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO PCB DES.
VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL
APPLICATION. COMPONENT SUBSTITUTION AND PRINTED
APP ENG.
CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT
PERFORMANCE OR RELIABILITY. CONTACT LINEAR
TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE.
VPRG2
VPRG1
SS
VFB
ANODE
LTC7138EMSE
U1
CUSTOMER NOTICE
R4
OPT
2. FOR 5V OUTPUT, VIN RANGE IS 6V-140V.
1. ALL RESISTORS ARE 0603.
ALL CAPACITORS ARE 0603.
JP3
OFF
3
NOTE: UNLESS OTHERWISE SPECIFIED
FB0
GND
E4
4V - 140V
VIN
E1
4
NC
NC
NC
NC
2
4
13
15
GND
8
GND
17
5
A
B
C
D
DEMO MANUAL DC2172A
Schematic Diagram
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7
DEMO MANUAL DC2172A
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
8
dc2172af
Linear Technology Corporation
LT 0115 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
●
FAX: (408) 434-0507 ● www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2015
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