Linear Technology DC1185B-A Quick setup guide

dc1185b-a/-bf

DEMO MANUAL

DC1185B-A/-B

DESCRIPTION

LTC3850EUF

Dual Phase/Dual Output

Synchronous Buck Converter

Demonstration circuit 1185 is a dual phase/dual output

synchronous buck converter featuring the LTC3850EUF.

The demo board comes in two versions. The output volt-

ages for version DC1185B-A are 2.0V/10A and 1.8V/10A.

The output voltages for version DC1185B-B are 1.5V/15A

and 1.2V/15A. The input voltage range is 6.5V to 14V for

both versions. For applications that have a 5V±0.5V input,

the board has an optional resistor to tie the INTVCC pin

to the VIN pin.

Thedemoboardusesahighdensity,2-sideddrop-inlayout.

Thepowercomponentsexcludingthe bulk output and input

capacitors, fit within a 1.35" ×0.75" area on the top layer.

The control circuit resides in a 0.60" ×0.75" area on the

bottom layer. The package style for the LTC3850EUF is a

4mm ×4mm 28-lead QFN with an exposed ground pad.

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

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

owners.

Note: Q1-Q4 MOSFETs changed on September 10, 2013.

See Schematic Diagram.

PERFORMANCE SUMMARY

The main features of the board include an internal 5V linear

regulator for bias, RUN pins for each output, an EXTVCC

pin and a PGOOD signal. The board can be configured

for either CCM (original setting), Burst Mode

, or pulse-

skipping operation with the MODE jumper. The board

also has optional resistors for single output/dual phase

operation, rail tracking, DCR sensing and synchronization

to an external clock.

Design files for this circuit board are available at

http://www.linear.com/demo

Specifications are at TA= 25°C

PARAMETER CONDITION VALUE

Minimum Input Voltage 6.5V

Maximum Input Voltage 14V

Version DC1185B-A

Output Voltage VOUT1 IOUT1 = 0A to 10A 2.0V ±2%

Output Voltage VOUT2 IOUT2 = 0A to 10A 1.8V ±2%

Nominal Switching Frequency 500kHz

Full-Load Efficiency

(See Figure 3 for Efficiency Curves)

VOUT1 = 2.0V, IOUT1 = 10A, VIN = 12V

VOUT2 = 1.8V, IOUT2 = 10A, VIN = 12V

90.2%

89.5%

Version DC1185B-B

Output Voltage VOUT1 IOUT1 = 0A to 15A 1.5V ±2%

Output Voltage VOUT2 IOUT2 = 0A to 15A 1.2V ±2%

Nominal Switching Frequency 400kHz

Full-Load Efficiency

(See Figure 4 for Efficiency Curves)

VOUT1 = 1.5V, IOUT1 = 15A, VIN = 12V

VOUT2 = 1.2V, IOUT2 = 15A, VIN = 12V

88.1%

86.5%

dc1185b-a/-bf

DEMO MANUAL

DC1185B-A/-B

QUICK START PROCEDURE

Demonstration circuit 1185 is easy to set up to evaluate

the performance of the LTC3850EUF. Refer to Figure 1

for the proper measurement equipment setup and follow

the procedure below:

Note: When measuring the output or input voltage ripple,

care must be taken to avoid a long ground lead on the

oscilloscope probe. See Figure 2 for the proper scope

probe technique. Short, stiff leads need to be soldered

to the (+) and (–) terminals of an output capacitor. The

probe’s ground ring needs to touch the (–) lead and the

probe tip needs to touch the (+) lead.

Place jumpers in the following positions:

JP1 RUN1 ON

JP2 RUN2 ON

JP3 MODE CCM

With power off, connect the input power supply to VIN

and GND.

Turn on the power at the input.

Note:Makesurethat the input voltage does not exceed 15V.

Check for the proper output voltages.

Version DC1158B-A:

VOUT1 = 1.960V to 2.040V

VOUT2 = 1.764V to 1.836V

Version DC1158B-B:

VOUT1 = 1.470V to 1.530V

VOUT2 = 1.176V to 1.224V

Once the proper output voltages are established, adjust

the loads within the operating range and observe the

output voltage regulation, ripple voltage, efficiency and

other parameters.

Note: Do not apply load across the VOSn+ and VOSn–

turrets. These turrets are only intended to Kelvin sense

the output voltage across COUT1 and COUT4. Heavy load

currents may damage the output voltage sense traces.

Figure 1. Proper Measurement Equipment Setup

dc1185b-a/-bf

DEMO MANUAL

DC1185B-A/-B

QUICK START PROCEDURE

SINGLE OUTPUT/DUAL PHASE OPERATION

VOUT

GND

COUT

Figure 2. Measuring Output Voltage Ripple

A single output/dual phase converter may be preferred

for high output current applications. The benefits of

single output/dual phase operation is lower ripple current

through the input and output capacitors, improved load

stepresponseand simplified thermal design. To implement

single output/dual phase operation, make the following

modifications:

1. Tie VOUT1 to VOUT2 by tying together the exposed

copper pads near J3 and J5 at the edge of the board.

Use a piece of heavy copper foil.

2. Tie ITH1 to ITH2 by stuffing 0Ω at R49.

3. Tie VFB1 to VFB2 by stuffing 0Ω at R50.

4. Tie TRK/SS1 to TRK/SS2 by stuffing 0Ω at R52.

5. Tie RUN1 to RUN2 by stuffing 0Ω at R55.

6. Remove the redundant ITH compensation network and

VFB divider.

LOAD CURRENT (A)

EFFICIENCY (%)

2.0V

1.8V

24 6 8 10 12

QTOP: RJK030DPB

QBOTTOM: RJK0330DPB

L: TOKO FDU0650-R56M = P3

0.56µH, DCR = 2.45mΩ, 3.2mΩ MAX

RSENSE = 3mΩ

LOAD CURRENT (A)

EFFICIENCY (%)

1.2V

36 9 12 15 18

QTOP: RJK030DPB

QBOTTOM: RJK0330DPB

L: VITEC 59PR9875

0.4µH, DCR = 0.47mΩ ±10%

RSENSE = 2mΩ

1.5V

2.0V/10A and 1.8V/10A Efficiency at VIN = 12V and fSW = 500kHz 1.5V/15A and 1.2V/15A Efficiency at VIN = 12V and fSW = 400kHz

Figure 3. Efficiency Curves for the DC1185B-A Figure 4. Efficiency Curves for the DC1185B-B

dc1185b-a/-bf

DEMO MANUAL

DC1185B-A/-B

RAIL TRACKING

Demonstration circuit 1185 is set up for independent

turn-on of VOUT1 and VOUT2. The ramp-rate for VOUT1 is

determined by the TRK/SS1 capacitor at C2 and the ramp-

rate for VOUT2 is determined by the TRK/SS2 capacitor

at C47. The turn-on of one rail will not affect the other for

the original demo board.

This board can be modified on the bench to allow VOUT1

to track an external signal. It can also be modified to

allow VOUT2 to track VOUT1 or to allow VOUT2 to track

an external signal. Tables 2 and 3 cover the rail tracking

options for each rail, with the DC3850B-B version used

as an example.

Table 1. VOUT1 Tracking Options for a 1.5V Output

TRACK 1 DIVIDER TRK/SS1 CAPACITOR

CONFIGURATION R3 R2 C2

Soft-Start without Tracking (Original Board) 0Ω Not Stuffed 0.1µF

External Coincident Tracking 17.8kΩ 20.0kΩ Not Stuffed

Table 2. VOUT2 Tracking Options for a 1.2V Output

TRACK 2 DIVIDER TRK/SS2 CAPACITOR

CONFIGURATION R36 R34 R37 C47

Soft-Start without Tracking (Original Board) 0Ω Not Stuffed Not Stuffed 0.1µF

Coincident Tracking to VOUT1 (1.5V) 0Ω 10.0kΩ 20.0kΩ Not Stuffed

External Coincident Tracking 10.0kΩ Not Stuffed 20.0kΩ Not Stuffed

dc1185b-a/-bf

DEMO MANUAL

DC1185B-A/-B

INDUCTOR DCR SENSING

Demonstration circuit 1185 provides an optional circuit

for DCR sensing. DCR sensing uses the DCR of the in-

ductor to sense the inductor current instead of discrete

sense resistors. The advantages of DCR sensing are lower

cost, reduced board space and higher efficiency, but the

disadvantage is a less accurate current limit. If DCR sens-

ing is used, be sure to select an inductor current with a

sufficiently high saturation current or use an iron powder

type. Tables 3 and 4 show an example of how to modify

the DC1185 for DCR sensing using these parameters:

VOUT1 = 2.0V/10A

VOUT2 = 1.8V/10A

VIN = 6.5V to 14V

fSW = 500kHz, typical

L1, L2 = Toko FDU0650-R56M=P3

(0.56µH, DCR = 2.45mΩ Typ, 3.2mΩ Max)

ILIM = Floating (R42, R44 = Open)

Table 3. VOUT1 Configured as a 2.0V/10A Converter Using DCR Sensing and Discrete Sense Resistors

RSENSE FILTER

RESISTORS

SENSE FIILTER

CAPACITOR

DCR FILTER/DIVIDER RESISTORS SENSE1– TO L1–

JUMPERTOP BOTTOM

CONFIGURATION RS1 L1 R29, R30 C14 R45 R47 R61

DCR Sensing Short with Cu

Strip or Very

Short and Thick

Piece of Wire

Toko

FDU0650-R56M=P3

Open 0.1µF 2.37kΩ 6.49kΩ 0Ω

Discrete RSENSE

(Original Board)

3mΩ

2010 Package

Toko

FDU0650-R56M=P3

100Ω 1nF Open Open Open

Table 4. VOUT2 Configured as a 1.8V/10A Converter Using DCR Sensing and Discrete Sense Resistors

RSENSE FILTER

RESISTORS

SENSE FIILTER

CAPACITOR

DCR FILTER/DIVIDER RESISTORS SENSE1– TO L1–

JUMPERTOP BOTTOM

CONFIGURATION RS2 L2 R39, R40 C15 R51 R53 R62

DCR Sensing Short with Cu

Strip or Very

Short and Thick

Piece of Wire

Toko

FDU0650-R56M=P3

Open 0.1µF 2.37kΩ 6.49kΩ 0Ω

Discrete RSENSE

(Original Board)

3mΩ

2010 Package

Toko

FDU0650-R56M=P3

100Ω 1nF Open Open Open

dc1185b-a/-bf

DEMO MANUAL

DC1185B-A/-B

SYNCHRONIZATION TO AN EXTERNAL CLOCK

The LTC3850 uses a phase-lock-loop which forces its

internal clock to be synchronized to an external clock.

Once synchronized, the rising edge of the top FET gate is

aligned to the rising edge of the external clock. The external

clock signal needs to be applied to the LTC3850’s MODE

pin which is tied to the turret labeled SYNC. The internal

phase lock loop is stabilized by a network on the FREQ pin

of the LTC3850. To set up the DC1185 for synchronization

to an external clock, follow the steps below.

1. Remove R7.

2. Stuff 10kΩ at R8.

3. Stuff 10nF at R10.

4. Leave 1nF at C12.

5. Float the MODE pin by placing the MODE jumper in the

BM position.

6. Apply the external clock from the turret la-beled SYNC

to GND.

dc1185b-a/-bf

DEMO MANUAL

DC1185B-A/-B

PARTS LIST

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER

Required Circuit Components

1 3 C11, C32, C36 CAP, 0805 4.7µF 10% 6.3V X5R AVX 08056D475KAT

2 5 C12, C14, C15, C41, C44 CAP, 0603 1nF 10% 50V X7R AVX 06035C102KAT

3 5 C2, C17, C20, C21, C47 CAP, 0603 0.1µF 10% 25V X7R TDK C1608X7R1E104K

4 2 C43, C42 CAP, 0603 100pF 5% 25V X7R AVX 06033C101JAT

5 1 CIN1 CAP, 180µF 20% 16V OSCON SANYO OSCON 16SVP180MX

6 2 CIN2, CIN3 CAP, 1210 10µF 10% 16V X5R TAIYO YUDEN EMK325BJ106KN-T

7 2 COUT1, COUT4 CAP, 1210 47µF 20% 6.3V X5R TDK C3225X5R0J476MT

8 4 COUT2, COUT3, COUT5, COUT6 CAP, 7343 330µF 20% 2.5V POSCAP SANYO 2R5TPE330M9

9 2 D2, D1 DIODE, CMDSH-3 SOD323 CENTRAL CMDSH-3TR

10 2 L1, L2 IND, 0.56µH TOKO FDU0650-R56M=P3

11 2 Q1, Q3 XSTR, N-CHANNEL MOSFET RENESAS RJK0305DPB

12 2 Q2, Q4 XSTR, N-CHANNEL MOSFET RENESAS RJK0330DPB

13 1 R10 RES, 0603 3.16k 1% 1/10W VISHAY CRCW06033K16FKEA

14 1 R18 RES, 0603 2.2Ω 5% 1/10W VISHAY CRCW06032R20JNEA

15 1 R27 RES, 0603 30.1k 1% 1/10W VISHAY CRCW060330K1FKEA

16 4 R29, R30, R39, R40 RES, 0603 100Ω 5% 1/10W VISHAY CRCW0603100RJNEA

17 2 R31,R35 RES, 0603 8.66k 1% 1/10W VISHAY CRCW06038K66FKEA

18 2 R32,R33 RES, 0603 20k 1% 1/10W VISHAY CRCW060320KFKEA

19 1 R43 RES, 0603 25.5k 1% 1/10W VISHAY CRCW060325K5FKEA

20 1 R46 RES, 0603 100k 5% 1/10W VISHAY CRCW0603100KJNEB

21 2 R7, R4 RES, 0603 10k 1% 1/16W VISHAY CRCW060310K0FKEB

22 3 R8, R9, R25 RES, 0603 0Ω JUMPER PANASONIC ERJ3GEY0R00V

23 2 RS2, RS1 RES, 2010 0.003Ω 5% 1/2W VISHAY WSL20103L000FEA

24 1 U1 IC, LTC3850EUF LINEAR TECH. LTC3850EUF

Additional Circuit Components

1 0 CIN5, CIN4 CAP, 1210 OPTION OPTION

2 0 C1, C37, C38, C47, C48, C49 CAP, 0603 OPTION OPTION

3 1 C50 CAP, 0603 1µF 20% 16V X7R AVX 0603YC105MAT2A

4 0 D4, D3 DIODE, SCHOTTKY 40V 3A OPTION OPTION

5 0 Q5, Q6, Q7, Q8 DO NOT STUFF OPTION

6 3 R1, R3, R36 RES, 0603 0Ω JUMPER PANASONIC ERJ3GEY0R00V

7 0 R2, R26, R28, R34, R37, R38, R41, R42,

R44, R45, R47, R49, R50-R53, R55,

R60-R62

RES, 0603 OPTION OPTION

Hardware

1 12 E1-E6, E9-E14 TURRET MILL-MAX 2501-2-00-80-00-00-07-0

2 2 JP2, JP1 HEADER, 3-PIN, 2mm SAMTEC TMM-103-02-L-S

3 1 JP3 HEADER, 4-PIN SAMTEC TMM-104-02-L-S

4 6 J1, J2, J3, J4, J5, J6 JACK, BANANA KEYSTONE 575-4

5 3 JP1-JP3 SHUNT, 2mm SAMTEC 2SN-BK-G

(DC1185B-A)

dc1185b-a/-bf

DEMO MANUAL

DC1185B-A/-B

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER

Required Circuit Components

1 3 C11, C32, C36 CAP, 0805 4.7µF 10% 6.3V X5R AVX 08056D475KAT

2 5 C12, C14, C15, C41, C44 CAP, 0603 1nF 10% 50V X7R AVX 06035C102KAT

3 5 C2, C17, C20, C21, C47 CAP, 0603 0.1µF 10% 25V X7R TDK C1608X7R1E104K

4 2 C43, C42 CAP, 0603 100pF 5% 25V X7R AVX 06033C101JAT

5 1 CIN1 CAP, 180µF 20% 16V OSCON SANYO OSCON 16SVP180MX

6 2 CIN2, CIN3 CAP, 1210 10µF 10% 16V X5R TAIYO YUDEN EMK325BJ106KN-T

7 2 COUT1, COUT4 CAP, 1210 100µF 20% 6.3V X5R TDK C3225X5R0J107MT

8 4 COUT2, COUT3, COUT5, COUT6 CAP, 7343 330µF 20% 2.5V POSCAP SANYO 2R5TPE330M9

9 2 D2, D1 DIODE, CMDSH-3 SOD323 CENTRAL CMDSH-3TR

10 2 L1, L2 IND, 0.4µH VITEC 59PR9875

11 2 Q1, Q3 XSTR, N-CHANNEL MOSFET RENESAS RJK0305DPB

12 2 Q2, Q4 XSTR, N-CHANNEL MOSFET RENESAS RJK0330DPB

13 1 R10 RES, 0603 2.55k 1% 1/10W VISHAY CRCW06032K55FKEB

14 1 R18 RES, 0603 2.2Ω 5% 1/10W VISHAY CRCW06032R20JNEA

15 1 R27 RES, 0603 17.8k 1% 1/10W VISHAY CRCW060317K8FKEA

16 4 R29, R30, R39, R40 RES, 0603 100Ω 5% 1/10W VISHAY CRCW0603100RJNEA

17 2 R31, R35 RES, 0603 5.9k 1% 1/10W VISHAY CRCW06035K90FKEA

18 2 R32, R33 RES, 0603 20k 1% 1/10W VISHAY CRCW060320KFKEA

19 1 R43 RES, 0603 10.0k 1% 1/10W VISHAY CRCW060310K0FKEB

20 1 R46 RES, 0603 100k 5% 1/10W VISHAY CRCW0603100KJNEB

21 2 R7, R4 RES, 0603 10k 1% 1/16W VISHAY CRCW060310K0FKEB

22 3 R8, R9, R25 RES, 0603 0Ω JUMPER PANASONIC ERJ3GEY0R00V

23 2 RS2, RS1 RES, 2010 0.002Ω 5% 1/2W VISHAY WSL20102L000FEA

24 1 U1 IC, LTC3850EUF LINEAR TECH. LTC3850EUF

Additional Circuit Components

1 0 CIN5, CIN4 CAP, 1210 OPTION OPTION

2 0 C1, C37, C38, C47, C48, C49 CAP, 0603 OPTION OPTION

3 1 C50 CAP, 0603 1µF 20% 16V X7R AVX 0603YC105MAT2A

4 0 D4, D3 DIODE, SCHOTTKY 40V 3A OPTION OPTION

5 0 Q5, Q6, Q7, Q8 DO NOT STUFF OPTION

6 3 R1, R3, R36 RES, 0603 0Ω JUMPER PANASONIC ERJ3GEY0R00V

7 0 R2, R26, R28, R34, R37, R38, R41,

R42, R44, R45, R47, R49, R50-R53,

R55, R60-R62

RES, 0603 OPTION OPTION

Hardware

1 12 E1-E6, E9-E14 TURRET MILL-MAX 2501-2-00-80-00-00-07-0

2 2 JP2, JP1 HEADER, 3-PIN, 2mm SAMTEC TMM-103-02-L-S

3 1 JP3 HEADER, 4-PIN SAMTEC TMM-104-02-L-S

4 6 J1, J2, J3, J4, J5, J6 JACK, BANANA KEYSTONE 575-4

5 3 JP1-JP3 SHUNT, 2mm SAMTEC 2SN-BK-G

PARTS LIST

(DC1185B-B)

dc1185b-a/-bf

DEMO MANUAL

DC1185B-A/-B

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

VO1-

VOUT1

VIN

TRK/SS1

EXTVCC

VOUT2

VO2-

[1]

VO1+

GND

VO2+

GND

VIN+

VIN-

GND

OFF

RUN1

RUN2

OFF

PGOOD

GND

SYNC

TRK/SS2

ASSY VOUT2 RS1, RS2 L1, 2 Q1, 3 Q2, 4 R27 R31, R35

2.0V/10A

1.5V/15A

VOUT1

1.8V/10A

1.2V/15A

0.003

0.002 VITEC 59PR9875

[1]

30.1K

17.8K

8.66K

5.9K

25.5K

10.0K

VOUT1 VOUT2

TOP FEED BACK R

ITH1 ITH2

OPTIONAL JUMPERS FOR

SINGLE OUTPUT/DUAL PHASE

OPERATION OPTIONAL DCR SENSING

NOTE:

WHEN DCR SENSING IS

CCMBM

0.4uH

R43

- A

- B

R10

3.16K

2.55K

FSW

NOTE:

RENESAS RJK0305DPB RENESAS RJK0330DPB

STUFF R60 WITH 0 OHMS FOR

4.6V<VIN<5.5V

COUT1/COUT4

47uF

100uF

TOKO FDU0650-R56M=P3

NOTE:

2010

SET RSENSE FILTER TIME CONSTANT 0.6nH/RSENSE FOR 2010 PACKAGE.

RENESAS RJK0330DPB

Represents

Tooling Holes

on PCB

REMOVE R30, R29, R40 & R39

2. FSW = 400kHz For Assy - B

CALCULATE R45, R47, C14 AND

R51, R53 & C15 PER THE DATA

SHEET. ALSO REFER TO QSG

FOR EXAMPLE.

STUFF R61 AND R62 WITH 0 OHMS.

IMPLEMENTED, SHORT RSENSE1 & RSENSE2.

6.5V - 14V

3. DO NOT APPLY LOAD FROM THE VO1+ TO VO1- OR FROM THE VO2+ TO VO2- TURRETS.

THESE ARE ONLY INTENDED TO KELVIN SENSE THE OUTPUT VOLTAGE ACROSS COUT1

AND COUT4.

1. FSW = 500kHz For Assy - A

1.1 CHANGE: Q1,Q2,Q3,Q4 08/04/13 MIKE S.

MIKE S.

MIKE S. 08/05/13

RENESAS RJK0305DPB

VSW2

VSW1

S1+

S1-

S2+

S2-

TRK/SS1

ITH2

VFB2

VFB1

RUN2

RUN1

EXTVCC

PGOOD

ITH1

TRK/SS2

ITH1

VFB1 VFB2

ITH2

TRK/SS2TRK/SS1

RUN2RUN1

VSW1 S1+

S1-

VSW2 S2+

S2-

VOUT1

VOUT2

VL1-

VL2-

VOUT1

INTVCC

VIN

INTVCC

VIN

INTVCCVIN

VIN

INTVCC

VIN

INTVCC

VINF

INTVCCVINF

VL1-

VL2-

REVISION HISTORY

DESCRIPTION DATE APPROVEDECO REV

PROD1 12/12/07

REVISION HISTORY

DESCRIPTION DATE APPROVEDECO REV

PROD1 12/12/07

REVISION HISTORY

DESCRIPTION DATE APPROVEDECO REV

PROD1 12/12/07

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

Applications Engineering for assistance.

This circuit is proprietary to Linear Technology and supplied

for use with Linear Technology parts.

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

Applications Engineering for assistance.

This circuit is proprietary to Linear Technology and supplied

for use with Linear Technology parts.

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

Applications Engineering for assistance.

This circuit is proprietary to Linear Technology and supplied

for use with Linear Technology parts.

SIZE

SCALE:

CAGE CODE

DWG NO

REV

SHEET OF

FILENAME:

TITLE

CONTRACT NO.

APPROVALS

DATE

DRAWN

CHECKED

APPROVED

ENGINEER

DESIGNER

TECHNOLOGY

1630 McCarthy Blvd.

Milpitas, CA 95035

Phone: (408)432-1900

Fax: (408)434-0507

DC1185B

Tuesday, September 10, 2013

SCH, LTC3850EUF, DUAL OUTPUT SYNCHRONOUS

1185B-1.DSNNONE

MEI

10/31/06

BUCK CONVERTER

SIZE

SCALE:

CAGE CODE

DWG NO

REV

SHEET OF

FILENAME:

TITLE

CONTRACT NO.

APPROVALS

DATE

DRAWN

CHECKED

APPROVED

ENGINEER

DESIGNER

TECHNOLOGY

1630 McCarthy Blvd.

Milpitas, CA 95035

Phone: (408)432-1900

Fax: (408)434-0507

DC1185B

Tuesday, September 10, 2013

SCH, LTC3850EUF, DUAL OUTPUT SYNCHRONOUS

1185B-1.DSNNONE

MEI

10/31/06

BUCK CONVERTER

SIZE

SCALE:

CAGE CODE

DWG NO

REV

SHEET OF

FILENAME:

TITLE

CONTRACT NO.

APPROVALS

DATE

DRAWN

CHECKED

APPROVED

ENGINEER

DESIGNER

TECHNOLOGY

1630 McCarthy Blvd.

Milpitas, CA 95035

Phone: (408)432-1900

Fax: (408)434-0507

DC1185B

Tuesday, September 10, 2013

SCH, LTC3850EUF, DUAL OUTPUT SYNCHRONOUS

1185B-1.DSNNONE

MEI

10/31/06

BUCK CONVERTER

X2X2

C14

1nF

C14

1nF

E2E2

R29

100

R29

100

COUT2

330uF

2.5V

COUT2

330uF

2.5V

COUT3

330uF

2.5V

COUT3

330uF

2.5V

R52

OPT

R52

OPT

E3E3

R61

OPT

R61

OPT

J6J6

R34

OPT

R34

OPT

CIN5

OPT

CIN5

OPT

CIN2

10uF

CIN2

10uF

R42

OPT

R42

OPT

C17

0.1uF

C17

0.1uF

R41

OPT

R41

OPT

E4E4

E14E14

R51

OPT

R51

OPT

R55

OPT

R55

OPT

[1]

E6E6

R62 OPTR62 OPT

C32

4.7uF

6.3V

C32

4.7uF

6.3V

R43

[1]

R43

[1]

CIN3

10uF

CIN3

10uF

C12

1nF

C12

1nF

C38

OPT

C38

OPT

E12E12

R25

C11

4.7uF

C11

4.7uF

LTC3850EUF

TRK/SS1

ITH1

VFB1

VFB2

ITH2

TRK/SS2

SENSE2- 7

SENSE2+ 8

RUN2

BG2 17

INTVCC 18

PGND 16

BG1 20

BOOST1 21

TG1 22

SW1 23

MODE

FREQ

SENSE1- 28

VIN 19

ILIM

EXTVCC

PGOOD

SW2 13

TG2 14

BOOST2 15

RUN1

SENSE1+ 27

SGND

E1E1

R45

OPT

R45

OPT

CIN4

OPT

CIN4

OPT

R39

100

R39

100

R32 20.0KR32 20.0K

RS2

[1]

RS2

[1]

R26

OPT

R26

OPT

R33 20.0KR33 20.0K

E13E13

JP3

MODE

JP3

MODE

CMDSH-3

OPT

2 1

R46

100K

R46

100K

J5J5

C20

0.1uF

C20

0.1uF

R40

100

R40

100

JP2JP2

R28

OPT

R28

OPT

L1 [1]L1 [1]

OPT

R27

[1]

R27

[1]

L2 [1]L2 [1]

C43 100pFC43 100pF

R9 0R9 0

[1]

R49

OPT

R49

OPT

R44

OPT

R44

OPT

10.0K

C21

0.1uF

C21

0.1uF

OPT

2 1

0.1uF

J2J2

COUT5

330uF

2.5V

COUT5

330uF

2.5V

X1X1

R60

OPT

R60

OPT

C41 1nFC41 1nF

R36 0R36 0

C36

4.7uF

6.3V

C36

4.7uF

6.3V

E10E10

OPT

CMDSH-3

C48

OPT

C48

OPT

R35

[1]

R35

[1]

OPT

C37

OPT

C37

OPT

COUT1

{1}

COUT1

{1}

C15

1nF

C15

1nF

J1J1

R31

[1]

R31

[1]

E9E9

C47

0.1uF

C47

0.1uF

C42

100pF

C42

100pF

E5E5

COUT6

330uF

2.5V

COUT6

330uF

2.5V

[1]

JP1JP1

R18 2.2R18 2.2

C49

OPT

C49

OPT

C44

1nF

C44

1nF

E11E11

R53

OPT

R53

OPT

RS1

[1]

RS1

[1]

OPT

R30

100

R30

100

OPT

J4J4

R47

OPT

R47

OPT

10.0K

C50

1uF

C50

1uF

J3J3

R37

OPT

R37

OPT

R50

OPT

R50

OPT

COUT4

{1}

COUT4

{1}

CIN1

180uF

16V

CIN1

180uF

16V

R10

[1]

R10

[1]

R38

OPT

R38

OPT

dc1185b-a/-bf

DEMO MANUAL

DC1185B-A/-B

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

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

 LINEAR TECHNOLOGY CORPORATION 2013

LT 1213 • PRINTED IN USA

DEMONSTRATION BOARD IMPORTANT NOTICE

Linear Technology Corporation (LT C ) 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 LT C 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 LT C 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.

LT C 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 LT C applica-

tion engineer.

Mailing Address:

Linear Technology

1630 McCarthy Blvd.

Milpitas, CA 95035

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