Analog Devices LINEAR TECHNOLOGY DC2234A Quick setup guide

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DEMO MANUAL DC2234A
Description
LT8711
Micropower Synchronous
Sepic Converter
Demonstration circuit 2234A is a synchronous sepic
converter featuring the LT
®
8711 multitopology switching
controller. The LT8711 is a current mode PWM DC/DC
controller with a dual input LDO to optimize gate driver
efficiency. Ultralow 15μA quiescent current in low noise
Burst Mode
®
operation achieves high efficiency at very
light loads and helps extend the run-time in battery pow-
ered applications when in standby mode. The LT8711
switching frequency can be programmed either via oscil-
lator resistor or external clock over a 100kHz to 750kHz
range.
The demo board regulates a 12V, 4A output from a 4.5V
to 40V input source, and operates at 200kHz switching
frequency. The rated maximum load current is 4A, while
derating is necessary for certain input voltage and thermal
conditions.
The SYNC pin on the demo board is grounded (JP1 at
BURST position) by default for low ripple high efficiency
Burst Mode operation at light load. To synchronize to an
external clock, move JP1 to SYNC and apply the external
clock to the SYNC turret. Force continuous conduction
mode can be selected by moving JP1 shunt to FCM posi-
tion. L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks
of Analog Devices, Inc. All other trademarks are the property of their respective owners.
performance summary
The DC2234A can be modified from a SEPIC converter to
other topologies. Synchronous BOOST and some other
schematics are provided in the data sheet. Please consult
the factory or LT8711 data sheet for details regarding
how to customize the DC2234A or how to design different
topologies for custom specifications.
The LT8711 includes many other features such as user
configurable under voltage lockout, soft-start, input volt-
age feedforward regulation, and it is easily configured
as synchronous buck, boost, SEPIC or nonsynchronous
buck-boost converter.
The data sheet gives a complete description of the device,
operation and application information. The data sheet
must be read in conjunction with this demo manual for
DC2234A. The LT8711 is assembled in a 20-lead plastic
TSSOP package with a thermally enhanced ground pad.
Proper board layout is essential for maximum thermal
performance. See the Layout Considerations section in
the data sheet.
Design files for this circuit board are available at
http://www.linear.com/demo/DC2234A
Specifications are at TA= 25°C
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN Input Voltage Range 4.5 40 V
VOUT Output Voltage 11.6 12 12.4 V
IOUT Maximum Output Current Derating is Necessary for Certain VIN and
Thermal Conditions
4 A
tSW Switching Frequency 185 200 215 kHz
EFF Efficiency at DC VIN = 5V, IOUT = 1A
VIN = 12V, IOUT = 2A
VIN = 24V, IOUT = 4A
VIN = 36V, IOUT = 4A
91.9
92
91.4
90.2
%
%
%
%
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DEMO MANUAL DC2234A
Quick start proceDure
DC2234A is easy to set up to evaluate the performance
of the LT8711. Refer to Figure 3 for proper measurement
equipment setup and follow the procedure below:
NOTE:When measuring the input or output voltage ripple,
care must be taken to avoid a long ground lead on the
oscilloscope probe. See Figure 4 for the proper scope
technique.
1. Set an input power supply that is capable of 40V/12A.
Then turn off the supply.
2. With power off, connect the supply to the input termi-
nals VIN and GND.
3. Turn on the power at the input.
NOTE:Make sure that the input voltage never exceeds
40V.
4. Check for the proper output voltage of 12V. Turn off
the power at the input.
5. Once the proper output voltage is established, connect
a variable load capable of sinking 4A at 12V to the out-
put terminals VOUT and GND. Set the current for 0A.
a. If efficiency measurements are desired, an ammeter
can be put in series with the output load in order to
measure the DC2234A’s output current.
b. A voltmeter can be placed across the output terminals
in order to get an accurate output voltage measure-
ment.
6. Turn on the power at the input.
NOTE:If there is no output, temporarily disconnect the
load to make sure that the load is not set too high.
7. Once the proper output voltage is again established,
adjust the load and/or input within the operating range
and observe the output voltage regulation, ripple volt-
age, efficiency and other desired parameters.
8. An external clock can be added to the SYNC termi-
nal when SYNC function is used (JP1 on the SYNC
position). Please ensure that the chosen RT sets the
LT8711 switching frequency to equal or below the low-
est SYNC frequency. See the data sheet section, Clock
Synchronization.
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DEMO MANUAL DC2234A
Quick start proceDure
Figure 2. DC2234A Temperature Rising vs Input Voltage
Figure 1. Efficiency vs Load Current at 200kHz Switching Frequency
N-FET Temperature Rise P-FET Temperature Rise
IOUT (A)
0
EFFICIENCY (%)
100
95
85
60
90
80
75
70
65
55
50 21 3 3.5
DC2234a F01
41.50.5 2.5
5V INPUT
12V INPUT
24V INPUT
36V INPUT
INPUT VOLTAGE (V)
0
TEMPERATURE RISING (°C)
80
90
70
50
30
40
100
60
20
10
020 2510 35 40
DC2234a F02
45155 30
IOUT = 2A
IOUT = 3A
IOUT = 4A
INPUT VOLTAGE (V)
0
TEMPERATURE RISING (°C)
120
80
40
100
60
20
020 2510 35 40 45155 30
IOUT = 2A
IOUT = 3A
IOUT = 4A
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DEMO MANUAL DC2234A
Quick start proceDure
Figure 3. Proper Measurement Equipment Setup
Figure 4. Measuring Output Ripple
Figure 5. DC2234A 12V Input 2A to 4A Load Transient
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DEMO MANUAL DC2234A
parts List
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 6 C2, C3, C4, CIN2, CIN3, CIN4 CAP, X7R, 10µF, 50V, 10% 1210 MURATA, GRM32ER71H106KA12L
2 1 CO1 ALUM, POLYMER, 270µF, 16V, 20% PANASONIC, 16SVPC270M
3 3 CO2, CO3, CO4 CAP, X7R, 22µF, 25V, 10% 1210 MURATA, GRM32ER71E226KE15L
4 1 CO7 CAP, X7R, 10µF, 25V, 10% 1206 MURATA, GRM31CR71E106KA12L
5 1 C7 CAP, X7R, 10nF, 25V, 10% 0603 MURATA, GRM188R71E103KA01D
6 4 C11, C14, C18, C22 CAP, X7R, 2.2µF, 16V, 10% 0805 MURATA, GRM21BR71C225KA12L
7 1 C13 CAP, X7R, 4.7µF, 50V, 10% 1206 TDK, C3216X7R1H475K160AC
8 1 C15 CAP, X7R, 4.7nF, 25V, 10% 0603 MURATA, GRM188R71E472KA01D
9 1 C16 CAP, C0G, 100pF, 50V, 5% 0603 TDK, C1608C0G1H101J080AA
10 1 C17 CAP, X7R, 0.47µF 16V 10% 0603 MURATA, GRM188R71C474KA88D
11 1 C19 CAP, X7R, 1000pF, 100V, 10% 1206 MURATA, GRM319R72A102KA01D
12 1 D1 DIODE, 60V, 2A, POWERDI-123 DIODES INC, DFLS260-7
13 1 D2 DIODE, 80V, 125mA, SOD-523 DIODES INC, 1N4148WT-7
14 1 L2 IND, 8.2µH COILCRAFT, XAL1510-822MEB
15 1 L3 IND, 15µH COILCRAFT, XAL1510-153MEB
16 1 MN1 N-MOSFET, 80V, POWERPAK SO-8 VISHAY, SIR826ADP-T1-GE3
17 1 MP1 P-MOSFET, 60V, POWERFLAT 5x6 STMicroelectronics, STL42P6LLF6
18 2 R1, R3 RES, SENSE, 0.002Ω, 1.5W, 2%, KRL3216 SUSUMU, KRL3216E-C-R002-G-T5
19 6 R5, R9, R12, R14, R18, R19 RES, CHIP, 0Ω, 0.1W, 0603 NIC, NRC06ZOTRF
20 1 R6 RES, CHIP, 3.3Ω, 0.1W, 1%, 0603 VISHAY, CRCW06033R30FKEA
21 2 R7, R15 RES, CHIP, 10Ω, 0.1W, 1%, 0603 VISHAY, CRCW060310R0FKEA
22 1 R13 RES, CHIP, 1M, 0.1W, 1%, 0603 VISHAY, CRCW06031M00FKEA
23 1 R16 RES, CHIP, 71.5k, 0.1W, 1%, 0603 VISHAY, CRCW060371K5FKEA
24 2 R17,R23 RES, CHIP, 100k, 0.1W, 1%, 0603 NIC, NRC06F1003TRF
25 1 R21 RES, CHIP, 118k, 0.1W, 1%, 0603 NIC, NRC06F1183TRF
26 1 R22 RES, CHIP, 49.9k, 0.1W, 1%, 0603 VISHAY, CRCW060349K9FKEA
27 1 R24 RES, CHIP, 3.3Ω, 1/2W, 5%, 1210 VISHAY, CRCW12103R30JNEA
28 1 U1 IC, LT8711EFE 20-LEAD TSSOP LINEAR TECH, LT8711EFE#PBF
Additional Demo Board Circuit Components
1 1 CIN1 EP-CAP, 56µF, 50V, HVH SERIES SUN ELECT, 50HVH56M
2 0 CIN5, CIN6, CO5, CO6, C20(OPT) CAP, 1210
3 0 C1 (OPT) CAP, 2220
4 0 C6, C8, C9, C10, C12, C21(OPT) CAP, 0603
5 0 L1 (OPT) IND, 8.2µH
60 MN2 (OPT) N-MOSFET, POWERPAK SO-8
7 0 MP2 (OPT) P-MOSFET, POWERFLAT 5x6
8 0 R4 (OPT) RES, 1210
9 0 R20 (OPT) RES, 0603
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DEMO MANUAL DC2234A
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Hardware: For Demo Board Only
1 11 E1 TO E11 TESTPOINT, TURRET, 0.094" MILL-MAX, 2501-2-00-80-00-00-07-0
2 1 JP1 DOUBLE ROW HEADER 2 x 3 0.079" WURTH ELEKTRONIK, 62000621121
3 1 XJP1 SHUNT, 0.079" CENTER WURTH ELEKTRONIK, 60800213421
4 4 MH1 TO MH4 STAND-OFF, NYLON 0.50" TALL KEYSTONE, 8833 (SNAP ON)
parts List
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DEMO MANUAL DC2234A
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
DD
C C BB AA
4.5V - 40V
12V / 4A
PGND
VOUT
PGND
VIN
AGND
EN/FBIN
SYNC
1. ALL RESISTORS ARE 0603. ALL SMD CAPACITORS ARE 0603.
NOTE: UNLESS OTHERWISE SPECIFIED
(VIN > 5V)
INTVCC
INTVCC
E7
C9
OPT
CO6
1210
+
CO1 270uF 16V
16SVPC270M
C17
470nF
E4
R21
118k
(200kHz)
CIN2
10uF 50V 1210
C2
10uF 50V 1210
L3
15uH
XAL1510-153
R1
0.002
KRL3216E
R24
3.3
1210
CO4 1210
25V
L1B
OPT
32
C3 10uF
50V 1210
R20
OPT
U1
LT8711EFE
TG 10
EXTVCC 15
NC
18
FB 2
BG 11
ISN
7
ISP
6
BIAS 9
INTVEE 8
VC 3
SS
4
INTVCC
13
VIN
14
CSN
16
CSP
17
EN/FBIN
1
OPMODE
5
RT
20
SYNC
19
NC
12
GND
21
E11
R4
OPT
1210
R13
1M
R17 100K
R23
100K
C8 OPT
C1
OPT 2220
R19
0
C10
OPT
R9 0
MN1
SiR826ADP
4
53 62
1 7
8
D1
DFLS260
E1
JP1
FCM BURST SYNC
12
3
56
4
CO3
E3
CIN3 10uF
50V 1210
C16
100pF
R15
10
R18
0
R14 0
L1A
OPT
1 4
E9
L2
8.2uH
XAL1510-822
C4
10uF 50V 1210
E10
R16 71.5k
R6 3.3
C7
10nF
C6
OPT
CO5 OPT
D2
1N4148
SOD-523
21
R22 49.9K
MP2 OPT
C21
OPT
R5 0
C15
4.7nF
CO2 22uF E6
C13 4.7uF 50V 1206
C18 2.2uF 0805
R12 0
R7 10
C19
1nF 1206 100V
+
CIN1
56uF 50V 50HVH56M CIN6
OPT 1210
MP1
STL42P6LLF6
CO7
10uF
25V
1206
CIN4
10uF 50V 1210
MN2
OPT
4
53 62
1 7
8
E8 E5
C20 OPT
1210
R3
0.002
KRL3216E
C12
OPT
C14
2.2uF
0805
CIN5 OPT
1210
C22 2.2uF 0805
C11 2.2uF 0805
E2
RT
SS
ISN
EN/FBIN
NG
VC
BIAS
ISP
FB
VOUT
INTVEE
VIN
VIN
SYNC
BG
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DEMO MANUAL DC2234A
 LINEAR TECHNOLOGY CORPORATION 2017
LT 0917 • PRINTED IN USA
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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