Linear Technology DC1755A Quick setup guide

dc1755af

DEMO MANUAL DC1755A

DESCRIPTION

LTC3860EUH

Wide Input Range,

High Efficiency Step-Down

DC/DC Converter

Demonstration circuit DC1755A provides the user with

twohighcurrentdualphasesynchronousbuckconverters

driven by the LTC3860. These buck converters provide

outputs of 1.5V/50A and 1.2V/50A over an input voltage

range of 6V to 14V and a switching frequency of 500kHz.

The board can be easily modified for a 4-phase, single VO,

100A supply. The power stage for each phase consists

of the tri-state PWM compatible 6mm × 6mm Fairchild

DrMOS module and a 0.47μH 13.2mm × 12.8mm iron

powder type inductor from Würth. A high density, two

sideddrop-inlayoutisused.Theentireconverter,excluding

the bulk output and input capacitors, fits within a 2.25” ×

1.38” area on the board.

L, LT, LTC, LTM, 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

The main features of the board are listed below:

• High efficiency and high current density.

• Remote sensing for each output.

• Optional resistors to tie the two outputs together.

• Connectorandheadertotietwoormoreboardstogether

for up to 12-phase operation.

• RUN, PGOOD and TRACK/SS pins for each output.

• CLKIN and CLKOUT pins.

• Onboard bias voltage regulator.

• BNC connectors to monitor each output voltage.

Design files for this circuit board are available at

http://www.linear.com/demo

(TA= 25°C), no airﬂow.

PARAMETER CONDITIONS VALUE

Minimum Input Voltage 6V

Maximum Input Voltage 14V

Output Voltage VOUTA IOUTA = 0A to 50A, VIN = 6V to 14V 1.5V ± 2%

Output Voltage VOUTB IOUTB = 0A to 50A, VIN = 6V to 14V 1.2V ± 2%

VOUTA Maximum Output Current, IOUTA VIN = 6V to 14V, VOUTA = 1.5V 50A

VOUTB Maximum Output Current, IOUTB VIN = 6V to 14V, VOUTB = 1.2V 50A

Nominal Switching Frequency 500kHz

Efficiency

See Figures 2 and 3

VOUTA = 1.5V, IOUTA = 50A, VIN = 12V 90.2% Typical

VOUTB = 1.2V, IOUTB = 50A, VIN = 12V 89.2% Typical

dc1755af

DEMO MANUAL DC1755A

QUICK START PROCEDURE

Demonstration circuit 1755A is easy to set up to evalu-

ate the performance of the LTC3860EUH. Please refer to

Figure 1 for proper measurement equipment setup and

follow the procedure below.

1) With power off, connect the input supply, load and

meters as shown in Figure 1. Preset the load to 0A and

IN supply to be 0V. Place jumpers in the following

positions:

JP1 RUNA ON

JP2 RUNB ON

JP3 INT PWR BLK BIAS ON

2) Adjust the input voltage to be between 6V to 14V. VOUTA

should 1.5V ± 2%.

OUTB should 1.2V ± 2%.

3) Next, apply 50A load to each output and remeasure

OUT.

4) OncetheDCregulationisconfirmed,observetheoutput

voltage ripple, load step response, efficiency and other

parameters.

Note 1. No airflow is required at room temperature with

50A on both outputs. But for ambient temperatures higher

than 30°C, a cooling fan is recommended.

Note 2. Use the BNC connectors labeled VOUTA or VOUTB

to measure the output voltage ripple.

Note 3. Do not apply the load from the VOSA+turret to

the VOSA–turret or from the VOSB+turret to the VOSB–

turret. These turrets are only intended to monitor the

voltage across COUT3 and COUT13 respectively. Heavy

load currents applied across these turrets may damage

the converter.

DYNAMIC LOAD CIRCUIT (OPTIONAL)

Demonstration circuit 1755A provides a simple load step

circuit consisting of a MOSFET and sense resistor for each

rail. To apply a load step, follow the steps below.

1) Preset the amplitude of a pulse generator to 0.0V and

the duty cycle to 5% or less.

2) Connect the scope to the VOUT BNC connectors for

the rail under test with a coax cable. To monitor the

load step current, connect the scope probe across the

ISTEP+– turrets for that rail.

3) Connect the output of the pulse generator to the PULSE

GEN turret for the rail under test and connect the return

to one of the GND turrets.

4) With the converter running, slowly increase the

amplitude of the pulse generator output to provide the

desired load step pulse height. The scaling for the load

step signal is 10mV/A.

dc1755af

DEMO MANUAL DC1755A

Figure 1. Proper Measurement Equipment Setup

IOUTA

IIN

VIN

supply

VOUTA

-V

VOUTA

load VOUTB

load

A IOUTB

V VOUTB

VIN

Monitor voltage across COUT7

and COUT19 for accurate

efficiency measurements.

DC1755a F01

QUICK START PROCEDURE

dc1755af

DEMO MANUAL DC1755A

Figure 2. Efficiency Curves for the 1.5V Rail of the DC1755A Figure 3. Efficiency Curves for the 1.2V Rail of the DC1755A

Figure 4. Load Step Response of the 1.5V Rail Figure 5. Load Step Response of the 1.2V Rail

LOAD CURRENT (A)

DC1755a F02

10 20 30 40 6050

EFFICIENCY (%)

VIN = 6V

VIN = 10V

VIN = 12V

VIN = 14V

LOAD CURRENT (A)

DC1755a F03

10 20 30 40 6050

EFFICIENCY (%)

VIN = 6V

VIN = 10V

VIN = 12V

VIN = 14V

SINGLE OUTPUT/4-PHASE OPERATION

A single output/4-phase converter may be preferred for

higher output current applications. The optional compo-

nents required to tie the phases together are found on

sheet3oftheschematicinthelowerrighthandcorner.Totie

thetwooutputstogether,makethefollowingmodifications:

1) Select one rail to be the master.

a) If VOUTA is the master, then stuff 0Ω at R103 to

disable the error amplifier for VOUTB.

b)If VOUTB is the master, then stuff 0Ω at R104 to

disable the error amplifier for VOUTA.

2) Stuff 0Ω at R87, R88, R89 and R91 to tie the IAVG,

COMP, TRACK/SS and RUN signals together.

3) Remove the redundant compensation components.

6-PHASE AND 12-PHASE OPERATION

Twoormoreboardsmaybetiedtogetherforupto12-phase

operation.Toparalleltwoormoreboards,placetheboards

side by side. Connect J9 of one board to J10 of the ad-

jacent board (see sheet 3 of the schematic, lower right

hand corner). This will tie the IAVG, COMP, TRACK/SS and

DC1755a F04

25A

LOAD STEP

10A/DIV

1.5VO(AC)

50mV/DIV

20μs/DIV

50A

77mV

DC1755a F05

25A

LOAD STEP

10A/DIV

1.2VO(AC)

50mV/DIV

20μs/DIV

50A

81mV

QUICK START PROCEDURE

dc1755af

DEMO MANUAL DC1755A

Figure 6. Typical Setup for a 6-Phase + 2-Phase Converter

RUN signals of the adjacent boards together. Next, locate

the exposed copper shapes on the four corners of the

board on the top and bottom layers. Use these shapes to

tie the VOUT, VIN and GND planes of the adjacent boards.

Next, select which phases will be the master or the slave.

Figure 6 shows the typical setup for a 6-phase + 2-phase

converter. Figure 7 shows the typical setup for a 12-phase

converter. For additional help and support, contact your

local LTC sales office.

BOARD #2

SIDE A = SLAVE

SIDE B = INDEPENDENT DUAL PHASE RAIL

R87, R88, R89, R91 = NOT STUFFED

R101, R102 = NOT STUFFED

R103 = NOT STUFFED

R104 = 0

GND GND

TOP

BOTTOM

BOARD #1 BOARD #2

BOARD #2 BOARD #1

BOARD #1 = MASTER

R87, R88, R89, R91 = 0

R101, R102 = 0.0m

R103 = 0

R104 = NOT STUFFED

6 PHASE

CONVERTER

6 PHASE

CONVERTER

2 PHASE

NVERTER

DC1755a F06

QUICK START PROCEDURE

dc1755af

DEMO MANUAL DC1755A

Figure 7. Typical Setup for a 12-Phase Converter

GND GND GND

TOP

BOTTOM

BOARD #1 BOARD #2 BOARD #3

BOARD #3 BOARD #2 BOARD #1

BOARD #1 = MASTER

R87, R88, R89, R91 = 0

R101, R102 = 0.0m

R103 = 0

R104 = NOT STUFFED

BOARD #2 = SLAVE

R87, R88, R89, R91 = 0

R101, R102 = 0.0m

R103, R104 = 0

BOARD #3 = SLAVE

R87, R88, R89, R91 = 0

R101, R102 = 0.0m

R103, R104 = 0

Cu Cu

DC1755a F07

QUICK START PROCEDURE

dc1755af

DEMO MANUAL DC1755A

PARTS LIST

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER

Required Circuit Components

1 1 CIN1 CAP, 180μF 20% 16V OSCON SANYO 16SVP180MX

2 4 CIN3, CIN5, CIN7, CIN9 CAP, 1210 22μF 20% 16V X5R TDK C3225X5R1C226M

3 12 COUT1 to COUT3, COUT4 to COUT6,

COUT11 to COUT13, COUT14 to COUT16 CAP, 7343 330μF 20% 2.5V POSCAP SANYO 2R5TPE330M9L

4 8 COUT7 to COUT10, COUT17 to COUT20 CAP, 1206 100μF 20% 6.3V X5R MURATA GRM31CR60J107ME39L

5 2 C1 to A, C1 to B CAP, 0603 470pF 10% 25V NPO AVX 06033A471KAT2A

6 8 C1, C8, C9, C10, C13, C20, C21, C22 CAP, 0603 0.22μF 10% 25V X7R TDK C1608X7R1E224K

7 8 C2, C11, C14, C23, C31, C32, C33, C34 CAP, 0603 2.2μF 10% 16V X7R MURATA GRM188R61C225KE15

8 2 C4, C16 CAP, 0603 100pF 5% 25V NPO AVX 06033A101JAT2A

9 2 C2 to A, C2 to B CAP, 0603 68pF 5% 25V NPO AVX 06033A680JAT2A

10 2 C3 to A, C3 to B CAP, 0603 2200pF 25V X7R MURATA GRM188R71E222MA01

11 3 C7, C19, C28 CAP, 0603 1μF 20% 25V X5R AVX 06033D105MAT2A

12 4 L1, L2, L3, L4 IND, 0.47μH 20% WÜRTH 744355147

13 1 RB to A RES, 0603 13.3k 1% 1/10W VISHAY CRCW060313K3FKEA

14 1 RB to B RES, 0603 20k 1% 1/10W NIC NRC06F2002TRF

15 19 R1, R11, R12, R16, R20, R25, R36, R45, R46,

R50, R54, R55, R59, R62, R69, R112, R113,

R116, R118

RES, 0603 0Ω JUMPER VISHAY CRCW06030000Z0EA

16 2 R1 to A, R1 to B RES, 0603 20k 1% 1/10W NIC NRC06F2002TRF

17 6 R2, R17, R37, R51, R57, R107 RES, 0603 1Ω 5% 1/10W VISHAY CRCW06031R00JNEA

18 2 R2 to A, R2 to B RES, 0603 6.8k 1% 1/10W VISHAY CRCW06036K80FKEA

19 2 R3 to A, R3 to B RES, 0603 523Ω 1% 1/10W VISHAY CRCW0603523RFKEA

20 9 R3, R4, R24, R26, R31, R38, R39, R61, R63 RES, 0603 10k 1% 1/10W VISHAY CRCW060310K0FKEA

21 2 R8, R43 RES, 0603 100k 5% 1/10W YAGEO RC0603JR-07100KL

22 4 R15, R33, R49, R70 RES, 0603 2.87k 1% 1/10W VISHAY CRCW06032K87FKEA

23 2 R18, R52 RES, 0603 59.0k 1% 1/10W VISHAY CRCW060359K0FKEA

24 4 R19, R21, R53, R56 RES, 0603 10Ω 1% 1/10W NIC NRC06F10R0TRF

25 2 R30, R67 RES, 0603 40.2k 1% 1/10W VISHAY CRCW060340K2FKEA

26 2 U1, U2 IC, DUAL OUTPUT BUCK CONVERTER LINEAR TECHNOLOGY LTC3860EUH

27 4 U3, U4, U5, U6 INTEGRATED MOSFET, DC/DC CONVERTER FAIRCHILD FDMF6707B

Bias Supply and UVLO Circuit

1 1 C29 CAP, 0603 2.2μF 10% 16V X7R MURATA GRM188R61C225KE15

2 1 C25 CAP, 0603 1μF 20% 25V X5R AVX 06033D105MAT2A

3 1 C26 CAP, 0805 10μF 10% 25V NPO AVX 08053D106MAT2A

4 1 C27 CAP, 0603 0.1μF 10% 16V X7R AVX 0603YC104KAT2A

5 1 C30 CAP, 0603 10pF 5% 50V NPO MURATA GQM1885C1H100JB01

6 1 D1 DIODE, BAV170 SOT23 DIODES INC., BAV170

7 1 D2 DIODE SHOTTKY SOD326 NXP PMEG2005AEA

8 1 L5 INDUCTOR 27μH 20% WÜRTH 7447789127

9 1 R105 RES, 0603 20k 1% 1/10W NIC NRC06F2002TRF

10 1 R106 RES, 0603 10k 1% 1/10W VISHAY CRCW060310K0FKEA

dc1755af

DEMO MANUAL DC1755A

PARTS LIST

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER

11 1 R90 RES, 1206 0Ω JUMPER VISHAY CRCW12060000Z0EA

12 1 R93 RES, 0603 100Ω 5% 1/10W VISHAY CRCW0603100RFKEA

13 1 R97 RES, 0603 105k 1% 1/10W VISHAY CRCW0603105KFKEA

14 1 R100 RES, 0603 127k 1% 1/10W VISHAY CRCW0603127KFKEA

15 1 U7 IC, STEP DOWN REGULATOR, DFN LINEAR TECHNOLOGY LT3502EDC

16 1 U8 IC, VOLTAGE MONITOR, DC-3 LINEAR TECHNOLOGY LT6703IDC-3

Additional Circuit Components

1 0 CIN2 CAP, SANYO SVP-F8 OPTIONAL

2 0 CIN4, CIN6, CIN8, CIN10 to CIN12 CAP, 1210 OPTIONAL

3 0 COUT21 to COUT26, COUT31 to COUT36 CAP, 7343H OPTIONAL

4 0 COUT27 to COUT30, COUT37 to COUT48 CAP, 1206 OPTIONAL

5 0 R5, R6, R7, R9, R10, R13, R14, R23, R27,

R28, R29, R32, R34, R35, R40, R41, R42, R44,

R47, R48, R58, R60, R64, R65, R66, R68, R71,

R72, R87, R88, R89, R91, R92, R94, R95, R96,

R103, R104, R108, R110, R111, R114, R115,

R117, R119

RES, 0603 OPTIONAL

6 0 C3, C5, C6, C12, C15, C17, C18, C24 CAP, 0603 OPTIONAL

7 0 Q2, Q3 MOSFET, TO-252 OPTIONAL

8 0 R73, R74, R77, R78, R83, R84, R85, R86 RES, 0603 OPTIONAL

9 0 R80, R82, R101, R102 RES, 2010 OPTIONAL

10 2 Q1, Q4 MOSFET, TO-252 VISHAY SUD50N03-09P

11 2 R75, R76 RES, 0603 10k 1% 1/10W VISHAY CRCW060310K0FKEA

12 2 R79, R81 RES, 2010 0.010Ω 2% 1W IRC LRC-LRF2010LF-01-R010-F

Hardware/Components (For Demo Board Only)

1 4 STANDOFF, SNAP ON KEYSTONE 8831

2 12 NUT, BRASS #10-32 ANY

3 6 RING, LUG #10 KEYSTONE 8205

4 6 WASHER, TIN, PLATED BRASS ANY

5 24 E1 to E11, E14, E16, E17 to E27 TURRET MILL MAX 2501-2-00-80-00-00-07-0

6 3 JP1 to JP3 HEADER, 3 PIN SAMTEC TMM-103-02-L-S

7 3 XJP1 to XJP3 SHUNT, 2mm CTRS SAMTEC 2SN-BK-G

8 6 J1 to J4, J11, J12 STUD, TEST PIN PEM KFH-032-10

9 2 J7, J8 CON, BNC, 5 PINS CONNEX 112404

10 1 J9 HEADER, DOUBLE ROW, RIGHT ANGLE MILL-MAX 802-40-008-20-001000

11 1 J10 SOCKET, DOUBLE ROW MILL-MAX 803-43-008-20-001000

dc1755af

DEMO MANUAL DC1755A

SCHEMATIC DIAGRAM

4 4

3 3

2 2

1 1

FSWITCH = 500kHz

TYPICAL

PHASES 1 AND 2

CAPACITORS AND RESISTORS ARE 0603

UNLESS OTHERWISE SPECIFIED.

VCCA

5VBIAS

CLKOUTA

VCCA

VIN

VDIFA

IAVGA

COMPA

ILIMA

VCCA

THDN1

DISBL#1

PWMEN1

PWMEN2

THDN2

DISBL#2

VOSA-

VOA+

FBA

CLKINA

VIN

RUNA

VOB+

VCCA

TRACK/SSA

VCCA

VOSA+

VIN

VDIFA

5VBIAS

VOSA-

VOSA+

REVISION HISTORY

DESCRIPTION DATEAPPROVEDECO REV

MIKE S

PRODUCTION 11-82-902

REVISION HISTORY

DESCRIPTION DATEAPPROVEDECO REV

MIKE S

PRODUCTION 11-82-902

REVISION HISTORY

DESCRIPTION DATEAPPROVEDECO REV

MIKE S

PRODUCTION 11-82-902

SIZE

DATE:

.VER.ONCI

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, January 16, 2012

DUAL OUTPUT 4 -PHASE STEP-DOWN CONVERTER

MIKE S.

N/A

LTC3860EUH

DEMO CIRCUIT 1755A

SIZE

DATE:

.VER.ONCI

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, January 16, 2012

DUAL OUTPUT 4 -PHASE STEP-DOWN CONVERTER

MIKE S.

N/A

LTC3860EUH

DEMO CIRCUIT 1755A

SIZE

DATE:

.VER.ONCI

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, January 16, 2012

DUAL OUTPUT 4 -PHASE STEP-DOWN CONVERTER

MIKE S.

N/A

LTC3860EUH

DEMO CIRCUIT 1755A

R6 OPTR6 OPT

LTC3860EUH

VCC

FB1

COMP1

VSNSOUT

VSNSN

VSNSP

COMP2

FB2

TRK/SS2

RUN2 17

ILIM2 18

PWM2

ISNS1N 21

ISNS2N 20

ISNS1P 22

ILIM1 23

RUN1 24

PWM1 25

IAVG 28

ISNS2P 19

FREQ

CLKIN

CLKOUT

PHSMD

PGOOD2

PWMEN2

15 PWMEN1 26

PGOOD1 27

SGND 29

SGND 30

VINSNS 31

TRK/SS1 32

GND

0.47uH

744355147

WURTH EL.

0.47uH

744355147

WURTH EL.

FDMF6707B

SMOD# 1

VCIN 2

VDRV 3

BOOT 4

CGND 5

GH 6

PHASE 7

NC 8

VIN 9

VIN 10

VIN

VSWH

PGND

VSWH 31

PGND

VSWH

29 VSWH

VSWH 32

VSWH 33

VSWH 34

VSWH 35

GL 36

CGND 37

THWN 38

DISB# 39

PWM 40

VSWH

VIN 42

GND 41

E6 VOSA-

COUT7

100uF

6.3V

1206

COUT7

100uF

6.3V

1206

JP1

OFF

RUNA

JP1

OFF

RUNA

CIN12

OPT

1210

CIN12

OPT

1210

0.47uH

744355147

WURTH EL.

0.47uH

744355147

WURTH EL.

OPT

CIN4

OPT

1210

CIN4

OPT

1210

R11

C12

OPT

C12

OPT

R16

CLKINA E7

CLKINA

R30

40.2K

R30

40.2K

R12

RB-A

13.3K

RB-A

13.3K

C32

2.2uF

16V

C32

2.2uF

16V

R15

2.87K

R15

2.87K

1uF

R29

OPT

R29

OPT

FDMF6707B

SMOD# 1

VCIN 2

VDRV 3

BOOT 4

CGND 5

GH 6

PHASE 7

NC 8

VIN 9

VIN 10

VIN

VSWH

PGND

VSWH 31

PGND

VSWH

29 VSWH

VSWH 32

VSWH 33

VSWH 34

VSWH 35

GL 36

CGND 37

THWN 38

DISB# 39

PWM 40

VSWH

VIN 42

GND 41

R35

OPT

R35

OPT

R27

OPT

R27

OPT

R110

OPT

R110

OPT

R18

59.0k

R18

59.0k

GND E9

GND

2.2uF

16V

2.2uF

16V

CIN11

OPT

1210

CIN11

OPT

1210

R13

OPT

R13

OPT

C11

2.2uF

16V

C11

2.2uF

16V

R17

R26

10K

R26

10K

R31

10k

R31

10k

100K

E5 VOSA+

R1 0R1 0

C2-A

68pF

C2-A

68pF

10K

COUT4

330uF

2.5V

COUT4

330uF

2.5V

R20 0R20 0

R21R21

OPT

R34

OPT

R34

OPT

R117

OPT

R117

OPT

100pF

TRACK/SSA E4

TRACK/SSA

R116

R3-A

523

R3-A

523

TP1TP1

R28

OPT

R28

OPT

R33

2.87K

R33

2.87K

C31

2.2uF

16V

C31

2.2uF

16V

CIN6

OPT

1210

CIN6

OPT

1210

0.22uF

R23

OPT

R23

OPT

CIN5

22uF

16V

1210

CIN5

22uF

16V

1210

R10

OPT

R10

OPT

10K

OPT

PGOODA

OPT

COUT8

100uF

6.3V

1206

COUT8

100uF

6.3V

1206

R2-A

6.8k

R2-A

6.8k

COUT2

330uF

2.5V

COUT2

330uF

2.5V

R21

J1 VIN

6V - 14V

J1 VIN

6V - 14V

R107

1R107

COUT9

100uF

6.3V

1206

COUT9

100uF

6.3V

1206

J4 GNDJ4 GND

0.22uF

R25 0R25 0

COUT1

330uF

2.5V

COUT1

330uF

2.5V

R24

10K

R24

10K

CIN3

22uF

16V

1210

CIN3

22uF

16V

1210

0.22uF

COUT5

330uF

2.5V

COUT5

330uF

2.5V

R19

CIN1

180uF

16V

CIN1

180uF

16V

COUT6

330uF

2.5V

COUT6

330uF

2.5V

C3-A

2200pF

C3-A

2200pF

COUT10

100uF

6.3V

1206

COUT10

100uF

6.3V

1206

E1 VIN+

TP2TP2

C10

0.22uF

C10

0.22uF

C1-A

470pF

C1-A

470pF

J2 GND

R32

OPT

R32

OPT

R1-A

20K

R1-A

20K

COUT3

330uF

2.5V

COUT3

330uF

2.5V

OPT

E2 VIN-

R14

OPT

R14

OPT

E8 GND

CIN2

OPT

CIN2

OPT

J3 VOUTA

1.5V / 50A

J3 VOUTA

1.5V / 50A

R112

dc1755af

DEMO MANUAL DC1755A

SCHEMATIC DIAGRAM

4 4

3 3

2 2

1 1

PHASES 3 AND 4

FSWITCH = 500kHz TYPICAL

VDIFB

PWMEN4

ILIMB

THDN4

VCCB

DISBL#4

VCCB

PWMEN3

IAVGB

VIN

VCCB

5VBIAS

VDIFB

VCCB

THDN3

VCCB

DISBL#3

COMPB

CLKOUTB

CLKOUTA

FBB

VIN

VCCB

RUNB

TRACK/SSB

VIN

VOSB+

VOSB-

VOB+

RUNB

5VBIAS

VOSB+

VOSB-

SIZE

DATE:

.VER.ONCI

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, January 16, 2012

DUAL OUTPUT 4 -PHASE STEP-DOWN CONVERTER

MIKE S.

N/A

LTC3860EUH

DEMO CIRCUIT 1755A

SIZE

DATE:

.VER.ONCI

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, January 16, 2012

DUAL OUTPUT 4 -PHASE STEP-DOWN CONVERTER

MIKE S.

N/A

LTC3860EUH

DEMO CIRCUIT 1755A

SIZE

DATE:

.VER.ONCI

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, January 16, 2012

DUAL OUTPUT 4 -PHASE STEP-DOWN CONVERTER

MIKE S.

N/A

LTC3860EUH

DEMO CIRCUIT 1755A

C13

0.22uF

C13

0.22uF

C17

OPT

C17

OPT

R36 0R36 0

E27 VOSB-

R113

R54 0R54 0 R61

10K

R61

10K

E10

PGOODB E10

PGOODB

COUT13

330uF

2.5V

COUT13

330uF

2.5V

COUT18

100uF

6.3V

1206

COUT18

100uF

6.3V

1206

LTC3860EUH

VCC

FB1

COMP1

VSNSOUT

VSNSN

VSNSP

COMP2

FB2

TRK/SS2

RUN2 17

ILIM2 18

PWM2

ISNS1N 21

ISNS2N 20

ISNS1P 22

ILIM1 23

RUN1 24

PWM1 25

IAVG 28

ISNS2P 19

FREQ

CLKIN

CLKOUT

PHSMD

PGOOD2

PWMEN2

15 PWMEN1 26

PGOOD1 27

SGND 29

SGND 30

VINSNS 31

TRK/SS1 32

GND

C22

0.22uF

C22

0.22uF

R38

10K

R38

10K

CIN7

22uF

16V

1210

CIN7

22uF

16V

1210

R3-B

523

R3-B

523

R119

OPT

R119

OPT

R47

OPT

R47

OPT

R49

2.87K

R49

2.87K

R111

OPT

R111

OPT

R45

R60

OPT

R60

OPT

C33

2.2uF

16V

C33

2.2uF

16V

R69 0R69 0

R46

R65

OPT

R65

OPT

R53

R39

10K

R39

10K

C15

OPT

C15

OPT

R2-B

6.8k

R2-B

6.8k

C16

100pF

C16

100pF

C24

OPT

C24

OPT

E16

GND E16

GND

C20

0.22uF

C20

0.22uF

R118

R63

10K

R63

10K

R56

COUT15

330uF

2.5V

COUT15

330uF

2.5V

E11

TRACK/SSB E11

TRACK/SSB

CIN8

OPT

1210

CIN8

OPT

1210

R48

OPT

R48

OPT

R66

OPT

R66

OPT

C21

0.22uF

C21

0.22uF

COUT17

100uF

6.3V

1206

COUT17

100uF

6.3V

1206

R59 0R59 0

FDMF6707B

SMOD# 1

VCIN 2

VDRV 3

BOOT 4

CGND 5

GH 6

PHASE 7

NC 8

VIN 9

VIN 10

VIN

VSWH

PGND

VSWH 31

PGND

VSWH

29 VSWH

VSWH 32

VSWH 33

VSWH 34

VSWH 35

GL 36

CGND 37

THWN 38

DISB# 39

PWM 40

VSWH

VIN 42

GND 41

J11 VOUTB

1.2V / 50A

J11 VOUTB

1.2V / 50A

COUT11

330uF

2.5V

COUT11

330uF

2.5V

R42

OPT

R42

OPT

0.47uH

744355147

WURTH EL.

0.47uH

744355147

WURTH EL.

TP4TP4

C1-B

470pF

C1-B

470pF

R68

OPT

R68

OPT

R44

OPT

R44

OPT

C18

OPT

C18

OPT

R72

OPT

R72

OPT

R62 0R62 0

R58

OPT

R58

OPT

R70

2.87K

R70

2.87K

R371R371

R64

OPT

R64

OPT

R51 1R51 1

C2-B

68pF

C2-B

68pF

CIN10

OPT

1210

CIN10

OPT

1210

JP2

OFF

RUNB

JP2

OFF

RUNB

0.47uH

744355147

WURST EL.

0.47uH

744355147

WURST EL.

R571R571

R40

OPT

R40

OPT

C19

1uF

C19

1uF

R1-B

20K

R1-B

20K

RB-B

20.0K

RB-B

20.0K

E14

CLKOUTB E14

CLKOUTB

C14

2.2uF

16V

C14

2.2uF

16V

J12 GND

C34

2.2uF

16V

C34

2.2uF

16V

CIN9

22uF

16V

1210

CIN9

22uF

16V

1210

R55 0

R41 OPTR41 OPT

COUT19

100uF

6.3V

1206

COUT19

100uF

6.3V

1206

COUT14

330uF

2.5V

COUT14

330uF

2.5V

COUT16

330uF

2.5V

COUT16

330uF

2.5V

R50

TP3TP3

R43

100K

R43

100K

C3-B

2200pF

C3-B

2200pF

R67

40.2K

R67

40.2K FDMF6707B

FDMF6707B

SMOD# 1

VCIN 2

VDRV 3

BOOT 4

CGND 5

GH 6

PHASE 7

NC 8

VIN 9

VIN 10

VIN

VSWH

PGND

VSWH 31

PGND

VSWH

29 VSWH

VSWH 32

VSWH 33

VSWH 34

VSWH 35

GL 36

CGND 37

THWN 38

DISB# 39

PWM 40

VSWH

VIN 42

GND 41

R52

59.0k

R52

59.0k

R71

OPT

R71

OPT

COUT12

330uF

2.5V

COUT12

330uF

2.5V

C23

2.2uF

16V

C23

2.2uF

16V COUT20

100uF

6.3V

1206

COUT20

100uF

6.3V

1206

E26 VOSB+

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