Linear Technologie DC1619A Guida rapida alla configurazione

dc1619af

DEMO MANUAL DC1619A

DESCRIPTION

LT3845A: High Voltage

Synchronous Buck Controller

with Programmable

Frequency and Sync

Demonstration Circuit 1619A is a 100kHz to 500kHz

programmable frequency, high voltage, current mode

DC/DC step-down converter featuring the LT

3845A. The

operating frequency can be synchronized up to 600kHz.

This demo board is designed for 12V up to 10A (120W)

outputfroma16Vto60Vinput.Asoft-startfeaturecontrols

the output voltage slew rate at start-up, reducing current

surges and voltage overshoots. The modes of operation

(BurstMode

, discontinuous currentmodeand continuous

current mode) are jumper selectable. Both Burst Mode

operation and discontinuous current mode increase the

efficiency at light loads. Continuous current mode will

maintain a constant switching frequency regardless of

the load current.

An optional boost bias circuit is provided on the bottom

side of the board for back-driving the LT3845A internal

regulator from the output voltage. Customers may want

to use this optional circuit with modified applications

that have relatively high input voltages and low (~3.3V)

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

output voltages. In such applications, this optional circuit

can increase the overall efficiency by reducing the power

loss in the LT3845A. The demonstration board has the

option of doubling the number of switching MOSFETs to

facilitate higher output current. This board is suitable for

a wide range of industrial control systems and telecom

power supplies.

The LT3845A 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 for demo circuit 1619A.

Note: It is best to ground the SYNC pin if the SYNC func-

tion is not being used.

Design files for this circuit board are available at

http://www.linear.com/demo

(TA= 25°C)

PARAMETER FOR BUCK REGULATOR CONDITION VALUE

Minimum Input Voltage 16V

Maximum Input Voltage 60V

Output Voltage, VOUT 12V ±2%

Maximum Output Current VIN < 28V

VIN ≥ 28V

7.5A to 10A (See Figure 5)

10A

Typical Switching Frequency R9 = 49.9k 300kHz

External Clock Synchronous Frequency Range R9 = 49.9k 325kHz to 600kHz

Efficiency VIN = 48V, VOUT = 12V, IOUT = 8A 94% (See Figure 3)

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dc1619af

DEMO MANUAL DC1619A

QUICK START PROCEDURE

Figure 1. Proper Measurement Equipment Setup

Demonstration circuit 1619A is easy to set up to evaluate

the performance of the LT3845A. Refer to Figure 1 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. Measure the input or output volt-

age ripple directly across the VIN or VOUT capacitors by

soldering leads on the appropriate capacitor. See Figure 2

for proper scope probe technique. An oscilloscope probe

can be directly connected to VIN or VOUT using a banana

jack to BNC adaptors.

1. Place JP1 in the RUN position.

2. Place JP2 in the desired operating mode: burst, pulse-

skipping or continuous.

3. With power off, connect the input power supply to VIN

and GND.

4. Turn on the power at the input and adjust the input

voltage until the LT3845A turns on.

Note: Make sure that the input voltage does not ex-

ceed60V.

5. Check for the proper output voltage.

Note: If output does not come up, make sure the load

is not set too high. Reduce the load and repeat steps

4 and5.

6. 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.

7. An external clock can be added to the SYNC pin when

the SYNC function is used. See the Oscillator SYNC

section in the data sheet for details.

–

–+

–

–+

0V TO 60V

7.5A

–

LOAD

0A TO 10A

–

DC1619 F01

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dc1619af

DEMO MANUAL DC1619A

QUICK START PROCEDURE

INPUT OR OUTPUT CAPACITOR

WIRE

Figure 2. Measuring Input or Output Ripple

Figure 3. DC1619A Burst Mode Efficiency

IOUT (A)

EFFICIENCY (%)

100

DC1619A F03

50 21 43 67 9

510

16VIN

20VIN

24VIN

36VIN

48VIN

60VIN

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dc1619af

DEMO MANUAL DC1619A

QUICK START PROCEDURE

Figure 4. DC1619A 2A to 8A Load Transient

Figure 5. DC1619A Output Current Derating Graph

VIN (V)

16 20 24

7.5

IOUT(MAX) (A)

8.0

8.5

9.0

9.5

10.0

28 32 36 40 44 48 52 56

DC1619A F05

10.5

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DEMO MANUAL DC1619A

PARTS LIST

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER

Required Circuit Components

1 2 CIN1, CIN2 CAP., SMT Aluminum, 33μF, 63V SUNCON, 63HVH33M

2 2 CIN3, CIN4 CAP., X7R, 2.2μF, 100V, 10%, 1210 MURATA,GRM32ER72A225KA35L

3 1 COUT1 CAP., POSCAP, 68μF, 16V, 20%, SANYO, 16TQC68M

4 1 COUT3 CAP., X5R, 22μF, 16V, 10%, 1210 TAIYO, EMK325BJ226KM-T

5 1 C1 CAP., X5R, 0.47μF, 100V, 10%, 1206 TDK, C3216X5R2A474KAT

6 2 C2, C5 CAP., X7R, 1500pF, 50V, 10%, 0402 AVX, 04025C152KAT

7 1 C4 CAP., C0G, 100pF, 50V, 10%, 0402 TDK, C1005COG1H101J

8 1 C6 CAP., X5R, 0.1μF, 16V, 10%, 0402 AVX, 0402YD104KAT

9 1 C7 CAP., X5R, 1μF, 16V, 10%, 0603 TDK, C1608X5R1C105K

10 1 C9 CAP., C0G, 220pF, 100V, 10%, 1206 VISHAY, VJ1206A221XB

11 1 D1 HIGH VOLTAGE SWITCHING DIODE, SOD-523 PHILLIPS, BAS521

12 1 D2 SMT SCHOTTKY BARRIER RECTIFIER, SMB DIODES INC, B160-13-F

13 1 D3 HIGH VOLTAGE SWITCHING DIODE, SOD-323 DIODES INC, 1N4148WS-7-F

14 1 L1 INDUCTOR, 10μH WURTH ELEKTRONIC, 74435561100

15 2 Q1, Q2 N-MOSFET, 80V INFINEON, BSC123N08NS3

16 1 R1 RES., CHIP, 1M, 1/16W, 1%, 0402 VISHAY, CRCW04021M00FKED

17 1 R2 RES., CHIP, 97.6k, 1/16W, 1%, 0402 VISHAY, CRW040297K6FKED

18 1 R4 RES., CHIP, 143k, 1/16W, 1%, 0402 VISHAY, CRCW0402143KFKED

19 1 R5 RES., CHIP, 16.2k, 1/16W, 1%, 0402 VISHAY,CRCW040216K2FKED

20 1 R7 RES., CHIP, 20k, 1/16W, 1%, 0402 VISHAY, CRCW040220K0FKED

21 1 R9 RES., CHIP, 49.9k, 1/16W, 1%, 0402 VISHAY,CRCW040249K9FKED

22 1 R10 RES., CHIP, 4.99Ω, 1/16W, 1%, 0402 VISHAY,CRCW04024R99FKED

23 1 R16 RES., CHIP, 6.65Ω, 1/4W, 1%, 1206 VISHAY, CRCW12066R65FKED

24 1 R17 RES., CHIP, 0.007Ω, 1W, 1%, 2512 VISHAY, WSL25127L000FEA

25 1 U1 I.C, LT3845AEFE#PBF, TSSOP (4.4MM) 16-PIN LINEAR TECH., LT3845AEFE#PBF

Additional Demo Board Circuit Components

1 0 COUT2 (OPT) CAP., POSCAP, 68μF, 16V, 20%, SANYO, 16TQC68M

2 0 COUT4 (OPT) CAP., X5R, 22μF, 16V, 10%, 1210 AVX, 1210YD226KAT

3 0 C3, C8, C10-C13 (OPT) CAP., 0402

4 0 D4, D5 (OPT) DUAL SMT SWITCHING DIODE, SOT-23 DIODES INC, BAV99-7-F

5 1 R3 RES., CHIP, 5.1M, 1/16W, 5%, 0402 PANASONIC, ERJ2GEJ515X

6 5 R11-R15 RES., CHIP, 0Ω, 1/16W, 0402 VISHAY, CRCW04020000Z0ED

7 1 R8 RES., CHIP, 100k, 1/16W, 1%, 0402 VISHAY, CRCW0402100KFKED

8 0 Q4, Q5 (OPT) N-MOSFET, 80V INFINEON, BSC123N08NS3

9 0 Q3 (OPT) COMPLIMENARY MOSFET PAIR, SC-70 VISHAY, Si1555DL-T1-E3

10 0 R6, R18-R22 (OPT) RES., 0402

Hardware For Demo Board Only

1 4 J1-J4 JACK, BANANA KEYSTONE, 575-4

2 5 E1-E5 TESTPOINT, TURRET, 0.095" MILL-MAX, 2501-2-00-80-00-00-07-0

3 1 JP1 JMP, 3-PIN 1 ROW 0.079CC SAMTEC, TMM-103-02-L-S

4 1 JP2 2MM DOUBLE ROW HEADER 2x3 SAMTEC, TMM-103-02-L-D

5 2 JP1(1 and 2), JP2 (5 and 6) SHUNT, 0.079" CENTER SAMTEC, 2SN-BK-G

6 4 STAND-OFF STAND-OFF, NYLON 0.50" tall KEYSTONE, 8833(SNAP ON)

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dc1619af

DEMO MANUAL DC1619A

SCHEMATIC DIAGRAM

A A

B B

CONT

BURST

PULSE SKIP

RUN

SHDN

NOTES:UNLESS OTHERWISE SPECIFIED

RESISTORS: OHMS, 0402

CAPACITORS: uF, 0402

* 79V CAPACITOR SURGE VOLTAGE

* L1 LAYOUT PADS ARE NON-STANDARD PADS DESIGNED TO

ACCOMMODATE THE WURTH ELEKTRONIC, 74435561100 INDUCTOR

OR THE WURTH ELEKTRONIC, 7443551151 INDUCTOR

MARTY M.PRODUCTION FAB- 2 11-15-10

REVISION HISTORY

DESCRIPTION DATEAPPROVEDECO REV

DEMO CIRCUIT 1619A

HIGH VOLTAGE SYNCHRONOUS BUCK

N/A LT3845AEFE

MARTY M.

CONTROLLER WITH ADJUSTABLE OPERATING FREQUENCY

11-15-10

SIZE

DATE:

IC NO. REV.

SHEET OF

TITLE:

APPROVALS

PCB DES.

APP ENG.

TECHNOLOGY

Fax: (408)434-0507

Milpitas, CA 95035

Phone: (408)432-1900

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

VFB VS+

VFB

VCC VCC

VOUT

VCC

VIN

16V - 60V

VIN

COUT1

68uF

16V

(OPT)

49.9K

GND

10uH*

R14 0

COUT3

22uF

16V

1210

VIN

GND

(OPT)

U1 LT3845AEFE

116

VFB

BURST_EN

SHDN

VIN BOOST

VCC

SYNC

FSET

SGND

PGND

SENSE-

SENSE+

1500pF

J4 VOUT

12V, 120W

R4 143K

220pF

100V

1206

CIN3

2.2uF

100V

1210

BSC123N08N

3 5

SYNC

BSC123N08N

3 5

R17

0.007

2512

5.1M

R15 0

CIN1

33uF

63V*

100pF

0.47uF

100V

1206

CIN4

2.2uF

100V

1210

COUT2

(OPT)

R12 0

100K

R11

97.6K

B160

1500pF

20K

GND

16.2K

1% E5

GND

BAS521

1uF

16V

0603

VOUT

JP2

MODE

R16

6.65

1206

COUT4

1210

(OPT)

R10

4.99

R13 0

1N4148

(OPT)

JP1

0.1uF 16V

CIN2

33uF

63V*

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dc1619af

DEMO MANUAL DC1619A

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

A A

B B

OPTIONAL BIAS CIRCUIT OPTIONAL POWER FETS

USE OPTIONAL BIAS CIRCUIT TO BACKFEED VCC WHEN VOUT IS BETWEEN

3V AND 9V AND VCC POWER DISSIPATION EXCEEDS 250mW.

REFER TO THE LT3845AEFE DATASHEET FOR MORE DETAILS.

DEMO CIRCUIT 1619A

HIGH VOLTAGE SYNCHRONOUS BUCK

N/A

LT3845AEFE

MARTY M.

CONTROLLER WITH ADJUSTABLE OPERATING FREQUENCY

11-15-10

SIZE

DATE:

IC NO. REV.

SHEET OF

TITLE:

APPROVALS

PCB DES.

APP ENG.

TECHNOLOGY

Fax: (408)434-0507

Milpitas, CA 95035

Phone: (408)432-1900

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 RESPONSIBILITYTO

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

2VOUT

3VOUT

VCC

VOUT

VIN

Q3A

Si1555DL

1 6

C12

1uF

10V Q5

3 5

C10

1uF

10V

BAV99

R21

C13 1uF

10V

R19 Q3B

Si1555DL

3 4

3 5

C11

1uF

10V

BAV99

R18

R22

R20

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dc1619af

DEMO MANUAL DC1619A

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ●FAX: (408) 434-0507 ●www.linear.com

LT 0211 • 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 applica-

tion engineer.

Mailing Address:

Linear Technology

1630 McCarthy Blvd.

Milpitas, CA 95035

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