Linear Technology LTC7138 Quick setup guide

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dc2172af
DEMO MANUAL DC2172A
Description
LTC7138
High Efficiency, High VIN,
Step-Down Regulator
Demonstrationcircuit2172Ais ahighinputvoltage,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. 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
• FBO turret to tie two or more LTC7138 regulators to-
gether 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
Specifications are at TA= 25°C
PARAMETER CONDITIONS VALUE
Input Voltage Range 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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dc2172af
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.
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.
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 Sum-
mary table.
5) Next, apply 400mA load to the output and re-measure
VOUT.
6) Oncethe DC regulation is confirmed, observethe output
voltage ripple, load step response, efficiency and other
parameters for the 5V, 3.3V and 1.8V output settings.
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.
Note 2. For a 5V output, the input voltage should be 6V
or more.
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.
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dc2172af
DEMO MANUAL DC2172A
Quick start proceDure
VOUT
LOAD
+
–
IOUT
VIN
SUPPLY
+
–
IIN
+ –
VOUT GND
COUT
Figure 1. Proper Measurement Equipment Setup
Figure 2. Measuring Output Voltage Ripple
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dc2172af
DEMO MANUAL DC2172A
Quick start proceDure
0
10
20
30
40
50
60
70
80
90
0.01 0.10 1 10 100 1,000
Efficiency (%)
Load Current (mA)
L = Sumida CDRH105RNP-151NC
(150µH, DCR = 285mΩ typ)
VOUT = 5V
140VIN
100VIN
48VIN
12VIN
dc2172a F03
Figure 3. Efficiency at 5VOUT
Figure 4. Efficiency at 3.3VOUT
0
10
20
30
40
50
60
70
80
0.01 0.10 1 10 100 1,000
Efficiency (%)
Load Current (mA)
dc2172a F04
140VIN
100VIN
48VIN
12VIN
VOUT = 3.3V
L = Sumida CDRH105RNP-151NC
(150µH, DCR = 285mΩ typ)
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dc2172af
DEMO MANUAL DC2172A
Quick start proceDure
Figure 5. Efficiency at 1.8VOUT
0
10
20
30
40
50
60
70
0.01 0.10 1 10 100 1,000
Efficiency (%)
Load Current (mA)
dc2172a F05
140VIN
100VIN
48VIN
12VIN
VOUT = 1.8V
L = Sumida CDRH105RNP-151NC
(150µH, DCR = 285mΩ typ)
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dc2172af
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
Hardware
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
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dc2172af
DEMO MANUAL DC2172A
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
schematic Diagram
5
5
4
4
3
3
2
2
1
1
D D CC
B B
A A
B B
B
B
A
A
A A
[3]
4V - 140V
1.8V / 3.3V / 5V
200V 400mA
2. FOR 5V OUTPUT, VIN RANGE IS 6V-140V. 1. ALL RESISTORS ARE 0603. ALL CAPACITORS ARE 0603.
NOTE: UNLESS OTHERWISE SPECIFIED
JP1 JP2VOUT
1.8V
3.3V
5.0V
EXT. R
REFER TO THE DATA SHEET FOR
APPLICATIONS INFORMATION.
4. SMALLER AMOUNT OF COUT CAN BE USED
FOR APPLICATIONS THAT CAN TOLERATE
HIGHER OUPUT RIPPLE.
VOUT
VIN
VIN
SIZE
DATE:
.VER.ONCI
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: [phone]
Milpitas, CA 95035
Phone: [phone]
1630 McCarthy Blvd. LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
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. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
Tuesday, January 06, 2015 1 1
HIGH EFFICIENCY, HIGH VIN, 400mA
N/A LTC7138EMSE
DEMO CIRCUIT 2172A
STEP-DOWN REGULATOR
SIZE
DATE:
.VER.ONCI
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: [phone]
Milpitas, CA 95035
Phone: [phone]
1630 McCarthy Blvd. LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
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. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
Tuesday, January 06, 2015 1 1
HIGH EFFICIENCY, HIGH VIN, 400mA
N/A LTC7138EMSE
DEMO CIRCUIT 2172A
STEP-DOWN REGULATOR
SIZE
DATE:
.VER.ONCI
SHEET OF
TITLE:
APPROVALS
PCB DES.
APP ENG.
TECHNOLOGY Fax: [phone]
Milpitas, CA 95035
Phone: [phone]
1630 McCarthy Blvd. LTC Confidential-For Customer Use Only
CUSTOMER NOTICE
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. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND
SCHEMATIC
SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS.
SCALE = NONE
www.linear.com
2
Tuesday, January 06, 2015 1 1
HIGH EFFICIENCY, HIGH VIN, 400mA
N/A LTC7138EMSE
DEMO CIRCUIT 2172A
STEP-DOWN REGULATOR
R8 OPT
JP3
ON OFF
RUN
1
3
2
JP2
A B
[3]
1 3 2
R7 OPT
C8
OPT
R1 2M
R2
OPT
C7
100uF
C6
100uF
1210 10V
R4
OPT
C10
OPT
1210
R3 0
E4
GND
R6 0
+
C1
22uF
E1
VIN
C4
47nF
C9
0.1uF
JP1
A B
[3]
1 3
2
C3
OPT
C2
1uF
200V
2220 D1
SBR1U200P1
L1 150uH
CDRH105R
E3
GND
E5
FB0
E2
VOUT
U1
LTC7138EMSE
SW 1
NC
2
VIN
3
NC
4
FBO
5
VPRG1 7
VPRG2 6
GND
8
VFB 9
SS 10
ISET
11
OVLO
12
NC
13
RUN
14
NC
15
ANODE 16
GND
17
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dc2172af
DEMO MANUAL DC2172A
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
[phone] ●FAX: [phone] ●www.linear.com
 LINEAR TECHNOLOGY CORPORATION 2015
LT 0115 • PRINTED IN USA
DEMONSTRATION BOARD IMPORTANT NOTICE
Linear Technology Corporation (LT C ) 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. LT C 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 LT C applica-
tion engineer.
Mailing Address:
Linear Technology
1630 McCarthy Blvd.
Milpitas, CA 95035
Copyright © 2004, Linear Technology Corporation
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