Linear Technology DC1940A Quick setup guide

dc1940af

DEMO MANUAL DC1940A

DESCRIPTION

Low Quiescent Current,

High Voltage Step-Down

Converter

Demonstration circuit 1940A is a low quiescent current,

synchronousbuckconverterfeaturingtheLTC

3891EUDC.

This demo board converts a 16V to 60V voltage to a 12V

at 15A output.

The main features of this board include an internal LDO

for gate drive power from VIN or EXTVCC, RUN and

PGOOD pins, a mode selector that allows the converter

to run in constant current mode (CCM), pulse-skipping or

Burst Mode

operation, and selectable current limit. The

DC1940Asupportsanadjustableoutputvoltage,soft-start

andtracking. The wide input voltage range of 16V to60V is

suitable for double battery automotive and distributed DC

power systems where low quiescent current is important.

The LTC3891 data sheet gives a complete description of

this part, operation and application information. The data

sheet must be read in conjunction with this quick start

guide for demo circuit 1940A.

The 60V avalanche rated MOSFETs, which are used

on DC1940A, can be operated at their rated voltage.

However, if application derating requirements are

stricter, MOSFETs with higher voltage rating can be used.

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

Please note, MOSFETs with higher voltage ratings may af-

fect the efficiency. If 60V MOSFETs are used, the MOSFET

avalanche rating and testing is typically done with 30%

over voltage margin (78V for 60V rated MOSFET). Please

check with particular MOSFET manufacturer to ensure the

avalanche voltage rating.

The DC1940A supports the following MOSFET packages:

LFPAK, PowerPAK SO-8 and Power 56. The subsequent

logic level (SV gate) MOSFETs can be used with DC1940A.

Si7850DP Vishay

RJK0651DPB Renesas

HAT2266H Renesas

BSC100N06LS3 G Infineon

FDMS86520L Fairchild

For synchronization to an external clock, remove jumper

JP2 and apply sync signal on terminal SYNC.

Design files for this circuit board are available at

http://www.linear.com/demo

(TA= 25°C)

PARAMETER CONDITIONS VALUE UNITS

Minimum Input Supply Voltage 16 V

Maximum Input Supply Voltage 60 V

Output Voltage Range VIN = 16V to 60V, IOUT1 = 0A to 5A 12 ± 2% V

Typical Switching Frequency 125 kHz

Typical Output Ripple (VOUT, 12V) ILOAD = 15A 80 mV

Efficiency Typical (VOUT, 12V) 97 %

Supply Quiescent Current VIN = 24V; VOUT = 12V, IO= 0A, Burst Mode Operation 50.8 μA

Supply Shutdown Current VIN = 24V 14.7 μA

dc1940af

DEMO MANUAL DC1940A

QUICK START PROCEDURE

Figure 1. Proper Measurement Equipment Setup

Demonstration circuit 1940A is easy to set up to evaluate

the performance of the LTC3891EUDC. 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 voltage

ripple by touching the probe tip directly across the VIN or

VOUT and GND terminals. See Figure 2 for proper scope

probe technique.

1. Place jumper JP1 in the ON position.

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

and GND.

3. Turn on the power at the input. Check for the proper

output voltages:

OUT1 = 11.9V to 12.4V

NOTE: If there is no output, temporarily disconnect the

load to make sure that the load is not set too high.

4. Once the proper output voltages are established, adjust

the load within the operating range and observe the

output voltage regulation, ripple voltage, efficiency and

other parameters.

DC1940a F01

dc1940af

DEMO MANUAL DC1940A

Figure 2. Measuring Input or Output Ripple

Figure 3. 12V Output, Efficiency vs Load, Burst Mode Operation, VIN 16V, 24V, 48V

QUICK START PROCEDURE

DC1940a F02

GND

VIN

LOAD (A)

EFFICIENCY (%)

DC1940a F03

0.01 0.1 1 10 100

16V

24V

48V

dc1940af

DEMO MANUAL DC1940A

PARTS LIST

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER

Required Circuit Components

1 3 C1, C2, C10 CAP, X7R, 2.2μF 100V 10%, 1812 TDK, C4532X7R2A225K

2 1 C3 CAP, EL, 56μF/63V, F4 SUN EL, 63HVH56M

3 1 C4 CAP, X7R, 0.1μF 100V 10%, 0603 MURATA, GRM188R72A104KA35D

4 1 C5 CAP, NPO,10pF, 50V, 5%, 0603 AVX, 06031A100JAT2A

5 2 C9, C13 CAP, X7R, 0.1μF 50V 10%, 0603 TDK, C1608X7R1H104K

6 1 C6 CAP, X5R, 4.7μF, 16V, 10%, 0805 MURATA, GRM219R61C475KE15D

7 2 C7, C17 CAP, X7R, 1μF 16V, 10%, 0603 TDK, C1608X7R1C105K

8 1 C8 CAP, NPO, 2.2pF 50V, ±0.25pF, 0603 AVX, 06035A2R2CAT

9 1 C12 CAP, X7R, 4700pF, 10V, 5%, 0603 AVX, 0603ZC472JAT2A

10 1 C14 CAP, NPO, 47pF 50V, 5%, 0603 NIC, NMC0603NPO470J50TRPF

11 1 C15 CAP, X7R, 10μF 16V 10%, 1206 MURATA, GCM31CR71C106KA64L

12 1 C16 CAP, SANYO, 150μF, 16V, 20% SANYO, 16TSVPC150

13 1 D1 DIODE, POWER DI-123 DIODES/ZETEX, DFLS1100-7

14 1 L1 IND, 10μH, 7443631000 WÜRTH, 7443631000

15 1 Q1 SILICON N CHANNEL POWER MOSFET LFPAK RENESAS, RJK0651DPB

16 1 Q2 SILICON N CHANNEL POWER MOSFET LFPAK RENESAS, RJK0653DPB

17 1 RS1 RES, 0.003Ω 1W 1% 2512 PANASONIC ERJM1WSF3M0U

18 1 R1 RES, 2.2 1% 1/10W, 0603 VISHAY, CRCW06032R20FNEA

19 3 R2, R8, R10 RES, 0Ω 1% 1/16W, 0603 VISHAY, CRCW06030000Z0EA

20 2 R4, R20 RES, 100k 1% 1/16W, 0603 VISHAY, CRCW0603100KFKEA

21 1 R5 RES, 511k 1% 1/16W, 0805 VISHAY, CRCW0805511KFKEA

22 1 R6 RES, 30.1k 1% 1/10W, 0603 VISHAY, CRCW060330K1FKEA

23 1 R7 RES, 35.7k 1% 1/16W, 0603 VISHAY, CRCW060335K7FKEA

24 1 R13 RES, 100 1% 1/10W, 0603 VISHAY, CRCW0603100RFKEA

25 1 R14 RES, 1M 1% 1/10W, 0805 VISHAY, CRCW08051M00FKEA

26 1 R15 RES, 2Ω 1% 1/16W, 0603 VISHAY, CRCW06032R00FNEA

27 1 R16 RES, 57.6k 1% 1/16W, 0603 VISHAY, CRCW060357K6FKEA

28 1 R17 RES, 15.4k 1% 1/10W, 0603 VISHAY, CRCW060315K4FKEA

29 1 R18 RES, 1k 1% 1/16W, 0603 VISHAY, CRCW06031K00FKEA

30 1 U1 IC, LTC3891EUDC, QFN20EUDC-3X4 LINEAR TECHNOLOGY, LTC3891EUDC

Additional Demo Board Circuit Components

1 R3, R9, R11, C11, R12,

C18, C19, R19, R21 RES, 0603 OPT

2 C20, C21, C22 CAP, 7343 OPT

3 Q3, Q4 (OPT) MOSFET, LFPAK OPT

Hardware

1 10 E1 TO E10 TESTPOINT, TURRET, 0.094" MILL-MAX, 2501-2-00-80-00-00-07-0

2 4 J1, J2, J3, J4 CONN, BANANA JACK, KEYSTONE-575-4 KEYSTONE 575-4

31JP1 JMP, 3PIN 1 ROW, 0.079" SULLINS, NRPN031PAEN-RC

41JP2 JMP, 3PIN 2 ROW, 0.079" SULLINS, NRPN032PAEN-RC

5 4 MTGS AT 4 CORNERS STANDOFF, NYLON 0.5 1/2" KEYSTONE, 8833(SNAP-ON)

6 2 XJP1, XJP2 SHUNT, 0.079" CENTER SAMTEC, 2SN-BK-G

dc1940af

DEMO MANUAL DC1940A

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

D D

C C

B B

A A

NOTES:

12V / 15A

16 - 60V

RUN

OFF

BURST

FCM

MODE

3. FOR SYNCHRONIZATION REMOVE JUMPER JP2 'MODE'

AND CONNECT SOURCE OF THE SYNC SIGNAL TO

TERMINALS E8 'SYNC' AND E9 'GND'

PULSE SKIP

1. ALL RESISTORS AND CAPACITORS ARE 0603

2. INSTALL SHUNTS AS SHOWN.

63HVH56M

SUN ELECT.

INTVCC

VIN

INTVCC

VOUT

VIN

VOUT

VIN

INTVCC

VOUT

INTVCC

VIN

REVISION HISTORY

DESCRIPTION DATEAPPROVEDECO REV

VICTOR K.PRODUCTION2 03-26-12

REVISION HISTORY

DESCRIPTION DATEAPPROVEDECO REV

VICTOR K.PRODUCTION2 03-26-12

REVISION HISTORY

DESCRIPTION DATEAPPROVEDECO REV

VICTOR K.PRODUCTION2 03-26-12

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

Monday, March 26, 2012

LOW QUIESCENT CURRENT HIGH VOLTAGE STEP-DOWN CONVERTER

VICTOR K

N/A

LTC3891EUDC

DEMO CIRCUIT 1940A

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

Monday, March 26, 2012

LOW QUIESCENT CURRENT HIGH VOLTAGE STEP-DOWN CONVERTER

VICTOR K

N/A

LTC3891EUDC

DEMO CIRCUIT 1940A

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

Monday, March 26, 2012

LOW QUIESCENT CURRENT HIGH VOLTAGE STEP-DOWN CONVERTER

VICTOR K

N/A

LTC3891EUDC

DEMO CIRCUIT 1940A

R17

15.4K

R17

15.4K

0.1uF

OPT

C11

OPT

C11

OPT

DFLS1100

E10

GND

E10

GND

RJK0651DPB Q1

RJK0651DPB

C13

0.1uF

50V

C13

0.1uF

50V

R16

57.6K

R16

57.6K

VOUT

GND

R21

OPT

R21

OPT

C19

OPT

C19

OPT

C20

OPT

7343

C20

OPT

7343

RS1

0.003

2512

RS1

0.003

2512

R15

OPT

C18

OPT

C18

OPT

R18

C10

2.2uF

100V

1812

C10

2.2uF

100V

1812

C17

1uF

C17

1uF

2.2uF

100V

1812

2.2uF

100V

1812

E7 GND

GND J2

GND

R13

100

R13

100

4.7uF

0805

4.7uF

0805

R11

OPT

R11

OPT

35.7K

EXTVCC

JP2JP2

5 6

30.1K

J4 GND

VIN E1

VIN

1uF

2.2uF

100V

1812

2.2uF

100V

1812

C12

4.7nF

C12

4.7nF

R12

OPT

R12

OPT

C16

150uF

16V

16SVPC150M

C16

150uF

16V

16SVPC150M

E6 VOUT

10pF

C15

10uF

1206

C15

10uF

1206

LTC3891EUDC

VIN

PGOOD

EXTVCC

TRACK/SS

RUN

ITH

SGND

PGND

PLLIN/MODE

ILIM

18 BG 13

SW 11

TG 10

BOOST 12

SENSE+ 6

SENSE- 5

INTVCC 14

VFB 7

FREQ 20

SGND

OPT

56uF/63V

10uH

2.2pF

C22

OPT

7343

C22

OPT

7343

R14

1 Meg

0805

R14

1 Meg

0805

PGOOD

VIN J1

VIN

100k

RJK0653DPB

511K

0805

511K

0805

JP1JP1

OPT

TRACK

C21

OPT

7343

C21

OPT

7343

SYNC

R19

OPT

R19

OPT

R20

100K

R20

100K

2.2

GND

C14

47pF

C14

47pF

R10

0.1uF

100V

0.1uF

100V

dc1940af

DEMO MANUAL DC1940A

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

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

LT 0612 • PRINTED IN USA

DEMONSTRATION BOARD IMPORTANT NOTICE

Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions:

Thisdemonstrationboard(DEMOBOARD)kitbeingsoldorprovidedbyLinear Technologyis intended for useforENGINEERING 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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