Linear Technology DC1891A Quick setup guide

dc1891af

DEMO MANUAL DC1891A

DESCRIPTION

LTC3862-2

Low Noise PolyPhase

SEPIC

DC/DC Converter

Demonstration circuit 1891A is a 2-phase high efficiency

nonisolated SEPIC (single ended primary inductor con-

verter) converter featuring the LTC

3862-2 switching

controller. The DC1891A converts a 6V to 60V input to

a12V output and provides 6A of output current. The

converter operates at 300kHz (600kHz output ripple) with

efficiency around 90%. With a proper amount of airflow,

the DC1891A converter can generate over 6A of output

current. The DC1891A can be easily modified to generate

output voltages in the range from 0.8V to 48V.

L, LT, LTC, LTM, Linear Technology, PolyPhase and the Linear logo are registered trademarks

of Linear Technology Corporation. All other trademarks are the property of their respective

owners.

PERFORMANCE SUMMARY

Also,theDC1891Acanbeoptimized forspecificinputvolt-

ages. The narrowing of input voltage range can increase

theconverter’sefficiency.Therefore,anarrowinputvoltage

range is more desirable.

The LTC3862-2 can be synchronized to an external clock

of up to 400kHz. Please refer to LTC3862-2 data sheet for

design details and applications information.

Design files for this circuit board are available at

http://www.linear.com/demo

PARAMETER CONDITIONS VALUE

Minimum Input Voltage IOUT = 0A to 6A 6V

Maximum Input Voltage IOUT = 0A to 6A 60V

VOUT VIN = 6V to 60V, IOUT = 0A to 6A 12V ±3%

Typical Output Ripple VOUT VIN = 6V to 60V, IOUT = 0A to 6A 100mVP-P

Nominal Switching Frequency 300kHz

Specifications are at TA= 25°C

dc1891af

DEMO MANUAL DC1891A

QUICK START PROCEDURE

Demonstration circuit 1891A is easy to set up to evaluate

theperformanceoftheLTC3862-2circuit.RefertoFigure1

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

the proper scope probe technique.

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

and GND. Make sure that the input power supply has

sufficient current rating at minimum input voltage for

the required output load.

2. Turn on the power at the input.

NOTE: Make sure that the input voltage does not exceed

60V.

3. Check for the proper output voltage.

VOUT = 12V, ±3%.

If there is no output, temporarily disconnect the load

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

4. Oncetheproperoutputvoltage isestablished,adjustthe

load within the operating range and observe the output

voltage regulation, ripple voltage, efficiency and other

parameters.

5. The DC1891A is equipped with an input capacitor CIN4

that is optional and is used to help with filtering when

the board is connected to the lab supply with long leads.

The capacitor CIN4 can be removed if the input power

source is close and has low source impedance.

CHANGING THE OUTPUT VOLTAGE

To set the output voltage lower or higher than 12V, change

the bottom voltage divider resistor connected to the FB

pin of U1 (see the Schematic Diagram). Also, check the

MOSFET, output diode and capacitor voltage ratings if the

output voltage is set higher than 12V.

The optional Q5 circuit is used to get the circuit running.

Once the circuit is running, the 12V output is used to

bias U1 via D2. The start-up circuit Q5 is turned off by Q6

when VOUT gets to the level set by D3, R14 and R16 that

activates Q6. Please contact the LTC factory for details.

dc1891af

DEMO MANUAL DC1891A

Figure 1. Proper Measurement Equipment Setup

QUICK START PROCEDURE

Figure 2. Measuring Input or Output Ripple

DC1891a F01

GND

VIN

DC1891a F02

dc1891af

DEMO MANUAL DC1891A

QUICK START PROCEDURE

Figure 3. Reducing the Input Voltage Range and Selecting

More Optimal MOSFET, Diode and Inductor Can Optimize the

Efficiency of DC1891A

Figure 4. Fast Transient Response of DC1891A is Achieved with a

Small Amount of Output Capacitance

Figure 5. The DC1891A Ramps the Output Slowly at Start-Up

without Generating an Input Current Surge

OUTPUT LOAD STEP RESPONSE

The load step response of DC1891A is very fast even

though a relatively small amount of output capacitance

is present (188µF ceramic and 440µF electrolytic). The

load step transients are shown in Figure 4. To improve

load step response further or to reduce the output ripple,

more output capacitance can be added. Low ESR output

capacitors will have the greatest effect on reducing the

ripple and load step transients.

SOFT-START FUNCTION

The DC1891A features a soft-start circuit that controls the

inrush current and output voltage ramp at start-up. The

capacitor CSS controls the start-up period. The start-up

waveforms are shown in Figure 5.

IOUT (A)

EFFICIENCY (%)

DC1891a F03

70 38

127

6V INPUT

12V INPUT

24V INPUT

48V INPUT

DC1891a F04

VOUT 200mV/DIV

IOUT 2A/DIV

VIN = 12V, VOUT = 12V

IOUT = 1A

3A LOAD STEP

500µs/DIV

DC1891a F05

VOUT 2V/DIV

50ms/DIV

IIN 2A/DIV

VIN = 12V, VOUT = 12V

IOUT = 5A

START-UP

dc1891af

DEMO MANUAL DC1891A

PARTS LIST

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER

Required Circuit Components

1 1 CC2 CAP, NPO 100pF, 25V, 5%, 0603 AVX 06033A101JAT2A

2 4 C3, C4, CSS, C5 CAP, X7R 0.01µF 25V 10% 0603 AVX 06033C103KAT2A

3 1 CC1 CAP, X5R 0.015µF 25V 10% 0603 AVX 06033D153KAT2A

4 1 C1 CAP, NPO 1000pF 25V 10% 0603 AVX 06033A102JAT2A

5 1 C2 CAP, X5R, 2.2µF, 25V, 10%, 0805 AVX 08053D225KAT2A

6 1 CIN4 CAP, 33µF, 63V SUN ELECT, 63HVH33MS

7 1 CU1 CAP, X7R 4.7µF 50V 10% 1206 MURATA GRM31CR71H475KA12L

8 7 CS1 TO CS4, CIN1 TO CIN3 CAP, X7S 4.7µF 100V 20% 1812 TDK C4532X7S2A475M

9 4 COUT1 TO COUT4 CAP, X7S 47µF 16V 20% 1812 TDK CKG45NX7S1C476M

10 2 COUT5, COUT6 CAP, 220µF 16V APXE UNITED CHEMI-CON APX160ARA221MHA0G

11 1 CF CAP, X7R 0.01µF 16V 10% 0603 AVX 0603YC103KAT2A

12 2 D3, D5 ZENER DIODE, SOD-323 NXP SEMI PDZ6.8B

13 1 D4 DIODE, SOD-523 NXP SEMI BAS516

14 2 D1, D2 SCHOTTKY RECTIFIER, TO-277A VISHAY V8P10-M3/86A

15 2 Q2, Q4 POWER MOSFET, PG-TDSON-8 INFINEON BSC060N10NS3G

16 1 Q5 PNP TRANSISTOR, SOT-23 NXP SEMI PBSS9110T

17 2 Q6, Q8 NPN TRANSISTOR, SOT-323 NXP SEMI PMST5550

18 1 Q7 NPN TRANSISTOR, SC-75 NXP SEMI BC847T

19 1 RC1 RES, CHIP 13.7k, 1% 0603 VISHAY CRCW060313K7FKEA

20 1 ROSC RES, CHIP 43.2k, 1% 0603 VISHAY CRCW060343K2FKED

21 2 R4, R10 RES, CHIP 10Ω 5% 0603 VISHAY CRCW060310R0JNEA

22 2 RF, R17 RES, CHIP 0Ω, Jumper 0603 VISHAY CRCW06030000Z0EA

23 1 R9 RES, CHIP 110k, 1% 0805 VISHAY CRCW0805110KFKEA

24 1 R1 RES, CHIP 12.4k, 1% 0603 VISHAY CRCW060312K4FKEA

25 1 R3 RES, CHIP 845k, 1% 0603 VISHAY CRCW0603845KFKEA

26 1 R11 RES, CHIP 249k, 1% 0603 VISHAY CRCW0603249KFKEA

27 2 R6, R8 RES, 0.005Ω, 1/2W, 1%, 2010 VISHAY WSL20105L000FEA

28 1 R12 RES, CHIP 33k, 1% 0603 VISHAY CRCW060333K0FKEA

29 1 R13 RES, CHIP 220k, 1% 0603 VISHAY CRCW0603220KFKEA

30 1 R14 RES, CHIP 56k, 1% 0603 VISHAY CRCW060356K0FKEA

31 2 R15, R16 RES, CHIP 10k, 1% 0603 VISHAY CRCW060310K0FKEA

32 1 R19 RES, CHIP 100k, 1% 0603 NIC NRC06F1003TRF

33 1 R20 RES, CHIP 180k, 1% 0603 VISHAY CRCW0603180KFKEA

34 2 T1,T2 COUPLED INDUCTOR, 6.8µH WÜRTH 7448709068

35 1 U1 PWM CONTROLLER LTC3862EFE-2 LINEAR TECHNOLOGY LTC3862EFE-2

dc1891af

DEMO MANUAL DC1891A

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER

Additional Demo Board Circuit Components

1 0 Q1, Q3 (OPT) MOSFET, PG-TDSON-8

2 0 R18 (OPT) RES, CHIP 0603

3 0 R7, R5 (OPT) RES, CHIP 2010

Hardware: For Demo Board Only

1 6 E3 TO E8 TESTPOINT, TURRET, 0.094" MILL-MAX 2501-2-00-80-00-00-07-0

2 2 E1, E2 STUD, TEST PIN PEM KFH-032-10ET

3 4 E1, E2 (2 each) NUT BRASS, # 10-32 M/S BR PL ANY 10-32

4 2 E1, E2 RING, LUG # 10 KEYSTONE, 8205

5 2 E1, E2 WASHER #10, TIN PLATED BRASS ANY #10EXT BZ TN

6 4 JP1 TO JP4 HEARDER, 3PIN 1 ROW 0.079CC SULLINS NRPN031PAEN-RC

7 4 JP1 TO JP4 SHUNT, 0.079" CENTER SAMTEC 2SN-BK-G

8 1 SW1 SWITCHE, SEALED TOGGLE C&K GT11MCBE (THRU-HOLE)

9 4 STAND-OFF STAND-OFF, NYLON 0.50" TALL KEYSTONE 8833(SNAP ON)

10 1 FAB, PRINTED CIRCUIT BOARD DEMO CIRCUIT 1891A

PARTS LIST

dc1891af

DEMO MANUAL DC1891A

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

4 4

3 3

2 2

1 1

BLANK SLOPE DMAX

Optional Bias Circuit

PHASE

1.0**

0.625

1.66

75%

84%**

96%

325ns

250ns**

175ns

120°

180°

RUN

OFF

.005

OPT

LTC3862EFE-2

6V-60V

12V / 6A

GORAN P.

OPT

See Demo Manual

HVH

APXE

100V

VOUT

+VIN

VOUT Vu1

Vu1

REVISION HISTORY

DESCRIPTION DATEAPPROVEDECO REV

Goran P.PRODUCTION25-23-12

REVISION HISTORY

DESCRIPTION DATEAPPROVEDECO REV

Goran P.PRODUCTION25-23-12

REVISION HISTORY

DESCRIPTION DATEAPPROVEDECO REV

Goran P.PRODUCTION25-23-12

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

Wednesday, August 01, 2012

LOW NOISE POLYPHASE SEPIC POWER CONVERTER

N/A

LTC3862EFE-2

DEMO CIRCUIT 1891A

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

Wednesday, August 01, 2012

LOW NOISE POLYPHASE SEPIC POWER CONVERTER

N/A

LTC3862EFE-2

DEMO CIRCUIT 1891A

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

Wednesday, August 01, 2012

LOW NOISE POLYPHASE SEPIC POWER CONVERTER

N/A

LTC3862EFE-2

DEMO CIRCUIT 1891A

R1 12.4kR1 12.4k

CC2

100pF

CC2

100pF

JP1JP1

E3E3

RC1

13.7k

RC1

13.7k

110k

R8R8

COUT2COUT2

Q1Q1

P10P10

GND

CU1 4.7uFCU1 4.7uF

R15

10k

R15

10k

JP2JP2

R6R6

BSC060N10NS3G

CC1

15nF

CC1

15nF

PDZ6.8B

2 1

RF 0RF 0

R10 10R10 10

U1U1

BLANK

PHASEMODE

FREQ

ITH

SGND

CLKOUT

SYNC

PLLFLTR

SENSE2+ 13

SENSE2- 14

NC 15

G2 16

PGND 17

G1 18

INTVCC 19

VIN 20

RUN 21

SENSE1- 22

SENSE1+ 23

3V8 24

DMAX

SLOPE

GND

R13

220k

R13

220k

R14

56k

R14

56k

PMST5550

2 3

P11P11

2.2uF

R19

100k

R19

100k

COUT3COUT3

SW1SW1

JP3JP3

R3 845kR3 845k

R20 180kR20 180k

+VOUT

CIN3CIN3

PBSS9110T

2 3

COUT6

+VIN

PMST5550

2 3

CSS 10nFCSS 10nF

GND

COUT5

220uF

16V

COUT5

220uF

16V

CS4 4.7uFCS4 4.7uF

ROSC 43.2kROSC 43.2k

BAS516

2 1

10nF

R16

10k

R16

10k

6.8uH

7448709060 T1

6.8uH

7448709060

3 4

1 2

CIN1 4.7uF

100V

CIN1 4.7uF

100V

JP4JP4

BSC060N10NS3G

V8P10

CIN2CIN2

CS2 4.7uFCS2 4.7uF

GND

10nF

C1 1nFC1 1nF

COUT1

47uF

16V

COUT1

47uF

16V

R7R7

CIN4

33uF

63V

CIN4

33uF

63V

BC847T

2 3

Q3Q3

GND

R17 0R17 0

6.8uH

7448709060 T2

6.8uH

7448709060

R5R5

PBZ6.8B

2 1

CS1 4.7uFCS1 4.7uF

R4 10R4 10

COUT4COUT4

R12

33k

R12

33k

R18 OPTR18 OPT

R11 249kR11 249k

GND

10nF

CS3 4.7uFCS3 4.7uF

0.01uF

V8P10

dc1891af

DEMO MANUAL DC1891A

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

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

 LINEAR TECHNOLOGY CORPORATION 2012

LT 0812 • PRINTED IN USA

DEMONSTRATION BOARD IMPORTANT NOTICE

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

Thisdemonstration board (DEMOBOARD) kit beingsold or providedby LinearTechnology isintended for usefor 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. 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.

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

Mouser Electronics

Authorized Distributor

Click to View Pricing, Inventory, Delivery & Lifecycle Information:

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DC1891A

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