Analog Devices LINEAR TECHNOLOGY DC2234A Guida rapida alla configurazione

dc2234af

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

91.4

90.2

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dc2234af

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)

EFFICIENCY (%)

100

50 21 3 3.5

DC2234a F01

41.50.5 2.5

5V INPUT

12V INPUT

24V INPUT

36V INPUT

INPUT VOLTAGE (V)

TEMPERATURE RISING (°C)

100

020 2510 35 40

DC2234a F02

45155 30

IOUT = 2A

IOUT = 3A

IOUT = 4A

INPUT VOLTAGE (V)

TEMPERATURE RISING (°C)

120

100

020 2510 35 40 45155 30

IOUT = 2A

IOUT = 3A

IOUT = 4A

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dc2234af

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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dc2234af

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

C C

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

OPT

CO6

1210

CO1

270uF

16V

16SVPC270M

C17

470nF

R21

118k

(200kHz)

CIN2

10uF

50V

1210

10uF

50V

1210

15uH

XAL1510-153

0.002

KRL3216E

R24

3.3

1210

CO4 1210

25V

L1B

OPT

C3 10uF

50V

1210

R20

OPT

LT8711EFE

TG 10

EXTVCC 15

FB 2

BG 11

ISN

ISP

BIAS 9

INTVEE 8

VC 3

INTVCC

VIN

CSN

CSP

EN/FBIN

OPMODE

SYNC

GND

E11

OPT

1210

R13

R17

100K

R23

100K

OPT

2220

R19

C10

OPT

MN1

SiR826ADP

53 62

1 7

DFLS260

JP1

FCM

BURST

SYNC

CO3

CIN3 10uF

50V

1210

C16

100pF

R15

R18

R14

L1A

OPT

1 4

8.2uH

XAL1510-822

10uF

50V

1210

E10

R16

71.5k

3.3

10nF

OPT

CO5

OPT

1N4148

SOD-523

R22

49.9K

MP2

OPT

C21

OPT

C15

4.7nF

CO2 22uF E6

C13

4.7uF

50V

1206

C18

2.2uF

0805

R12

C19

1nF

1206

100V

CIN1

56uF

50V

50HVH56M CIN6

OPT

1210

MP1

STL42P6LLF6

CO7

10uF

25V

1206

CIN4

10uF

50V

1210

MN2

OPT

53 62

1 7

C20 OPT

1210

0.002

KRL3216E

C12

OPT

C14

2.2uF

0805

CIN5 OPT

1210

C22

2.2uF

0805

C11

2.2uF

0805

ISN

EN/FBIN

BIAS

ISP

VOUT

INTVEE

VIN

SYNC

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dc2234af

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

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