Linear Technology DC1185B-A, DC1185B-B, LTC3850EUF Demo Manual

DESCRIPTION

DEMO MANUAL

DC1185B-A/-B

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.

The demo board uses a high density, 2-sided drop-in layout.
The power components excluding the 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.

PERFORMANCE SUMMARY

PARAMETER CONDITION VALUE

Minimum Input Voltage 6.5V

Maximum Input Voltage 14V

Specifications are at TA = 25°C

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
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

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.

®

, or pulse-

Version DC1185B-A

Output Voltage V

Output Voltage V

Nominal Switching Frequency 500kHz

Full-Load Efficiency
(See Figure 3 for Efficiency Curves)

Version DC1185B-B

Output Voltage V

Output Voltage V

Nominal Switching Frequency 400kHz

Full-Load Efficiency
(See Figure 4 for Efficiency Curves)

OUT1

OUT2

OUT1

OUT2

I

= 0A to 10A 2.0V ±2%

OUT1

I

= 0A to 10A 1.8V ±2%

OUT2

= 2.0V, I

V

OUT1

V

= 1.8V, I

OUT2

I

= 0A to 15A 1.5V ±2%

OUT1

I

= 0A to 15A 1.2V ±2%

OUT2

= 1.5V, I

V

OUT1

V

= 1.2V, I

OUT2

= 10A, VIN = 12V

OUT1

= 10A, VIN = 12V

OUT2

= 15A, VIN = 12V

OUT1

= 15A, VIN = 12V

OUT2

90.2%

89.5%

88.1%

86.5%

dc1185b-a/-bf

1

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: Make sure that the input voltage does not exceed 15V.

Check for the proper output voltages.

Version DC1158B-A:

V

V

Version DC1158B-B:

V

V

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:
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.

= 1.960V to 2.040V

OUT1

= 1.764V to 1.836V

OUT2

= 1.470V to 1.530V

OUT1

= 1.176V to 1.224V

OUT2

Do not apply load across the VOSn+ and VOSn –

2

Figure 1. Proper Measurement Equipment Setup

dc1185b-a/-bf

DEMO MANUAL

VOUT

GND

COUT

+

-

DC1185B-A/-B

QUICK START PROCEDURE

Figure 2. Measuring Output Voltage Ripple

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

95

90

85

80

EFFICIENCY (%)

QTOP: RJK030DPB
QBOTTOM: RJK0330DPB

75

L: TOKO FDU0650-R56M = P3

0.56µH, DCR = 2.45mΩ, 3.2mΩ MAX
R

70

0

= 3mΩ

SENSE

4 6 8

2

LOAD CURRENT (A)

2.0V

1.8V

10 12

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

SINGLE OUTPUT/DUAL PHASE OPERATION

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
step response and 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.

95

90

85

80

EFFICIENCY (%)

75

70

0

QTOP: RJK030DPB
QBOTTOM: RJK0330DPB
L: VITEC 59PR9875

0.4µH, DCR = 0.47mΩ ±10%
= 2mΩ

R

SENSE

6 9 12

3

LOAD CURRENT (A)

1.5V

1.2V

15 18

dc1185b-a/-bf

3

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 ramp­rate 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.

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

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

This board can be modified on the bench to allow VOUT1
to track an external signal. It can also be modified to
allow VOUT
an

external signal. Tables 2 and 3 cover the rail tracking

2 to track VOUT1 or to allow VOUT2 to track

options for each rail, with the DC3850B-B version used
as an example.

TRACK 2 DIVIDER TRK/SS2 CAPACITOR

4

dc1185b-a/-bf

INDUCTOR DCR SENSING

DEMO MANUAL

DC1185B-A/-B

Demonstration circuit 1185 provides an optional circuit
for DCR sensing. DCR sensing uses the DCR of the in­ductor to
sense

sense the inductor current instead of discrete

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

= 2.0V/10A

V

OUT1

= 1.8V/10A

V

OUT2

= 6.5V to 14V

V

IN

= 500kHz, typical

f

SW

L1, L2 = Toko FDU0650-R56M=P3
(0.56µH, DCR = 2.45mΩ Typ, 3.2

mΩ Max)

ILIM = Floating (R42, R44 = Open)

the DC1185 for DCR sensing using these parameters:

Table 3. V

CONFIGURATION RS1 L1 R29, R30 C14 R45 R47 R61

DCR Sensing Short with Cu

Discrete R
(Original Board)

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

OUT1

DCR FILTER/DIVIDER RESISTORS

2.37kΩ 6.49kΩ 0Ω

SENSE

Strip or Very
Short and Thick
Piece of Wire

3mΩ
2010 Package

Toko
FDU0650-R56M=P3

Toko
FDU0650-R56M=P3

R

FILTER

SENSE

RESISTORS

Open 0.1µF

100Ω 1nF Open Open Open

SENSE FIILTER

CAPACITOR

SENSE1– TO L1–

JUMPERTOP BOTTOM

Table 4. V

CONFIGURATION RS2 L2 R39, R40 C15 R51 R53 R62

DCR Sensing Short with Cu

Discrete R
(Original Board)

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

OUT2

DCR FILTER/DIVIDER RESISTORS

2.37kΩ 6.49kΩ 0Ω

SENSE

Strip or Very
Short and Thick
Piece of Wire

3mΩ
2010 Package

Toko
FDU0650-R56M=P3

Toko
FDU0650-R56M=P3

R

FILTER

SENSE

RESISTORS

Open 0.1µF

100Ω 1nF Open Open Open

SENSE FIILTER

CAPACITOR

SENSE1– TO L1–

JUMPERTOP BOTTOM

dc1185b-a/-bf

5

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.

6

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 08056D475K AT

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 06033C101J AT

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

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 0603YC105M AT2A

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,

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

1 R46 RES, 0603 100k 5% 1/10W VISHA

(DC1185B-A)

Y CRCW0603100KJNEB

RES, 0603 OPTION OPTION
R44, R45, R47, R49, R50-R53, R55,
R60-R62

dc1185b-a/-bf

7

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 08056D475K AT

2 5 C12, C14, C15, C41, C44 CAP, 0603 1nF 10% 50V X7R AVX 06035C102K AT

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

21

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,

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

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

(DC1185B-B)

5% 1/10W VISHAY CRCW0603100KJNEB

RES, 0603 OPTION OPTION
R42, R44, R45, R47, R49, R50-R53,
R55, R60-R62

8

dc1185b-a/-bf

SCHEMATIC DIAGRAM

1

2

3

4

5

6

7

8

A

B

C

D

11

11

11

DEMO MANUAL

DC1185B-A/-B

A

MIKE S.

REVISION HISTORY

REVISION HISTORY

REVISION HISTORY

PROD1 12/12/07

PROD1 12/12/07

PROD1 12/12/07

DESCRIPTION DATE APPROVEDECO REV

DESCRIPTION DATE APPROVEDECO REV

DESCRIPTION DATE APPROVEDECO REV

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

1.1

VIN

VIN+

J1J1

E5E5

VIN

6.5V - 14V

+

12

CIN1

180uF

180uF

VIN-

GND

J2J2

E6E6

16V+CIN1

16V

VIN

E11E11

VL1-

CIN4

OPT

CIN4

OPT

CIN2

10uF

CIN2

10uF

Q5

OPTQ5OPT

783
6
5

4

783
6
5

4

Q1

[1]Q1[1]

<

VO1+

L1 [1]L1 [1]

2
1

2
1

J3J3

VOUT1

RS1

RS1

VSW1

VOUT1

[1]

C32

C32

COUT1

COUT1

[1]

[1]

783
6
5

Q6

783
6
5

Q2

4.7uF

4.7uF

COUT3

+

COUT2

+

{1}

{1}

OPTQ6OPT

[1]Q2[1]

2010

6.3V

6.3V

330uF

330uF

330uF

330uF

D4

B

VO1-

GND

J4J4

E12E12

2.5V+COUT3

2.5V

2.5V+COUT2

2.5V

2 1

OPTD4OPT

4

4

VIN

2
1

2
1

INTVCC

VO2+

E13E13

VL2-

CIN5

OPT

CIN5

OPT

L2 [1]L2 [1]

CIN3

10uF

CIN3

10uF

Q7

OPTQ7OPT

783
6

2

5

1

4

783
6

2

5

1

4

Q3

[1]Q3[1]

J5J5

RS2

RS2

VOUT2

VOUT2

COUT6

COUT5

[1]

[1]

VSW2

Q8

Q4

[1]

C36

4.7uF

C36

4.7uF

330uF

2.5V+COUT6

330uF

2.5V

+

330uF

2.5V+COUT5

330uF

2.5V

+

COUT4

{1}

COUT4

{1}

2010

D3

783
6
5

OPTQ8OPT

783
6
5

[1]Q4[1]

C

X2X2

X1X1

VO2-

GND

J6J6

E14E14

6.3V

6.3V

2 1

OPTD3OPT

2
1

4

2
1

4

1

1

Represents

VL1-

R61

R61

S1-

R47

OPT

R47

OPT

R45

R45

OPT

OPT

VSW1 S1+

IMPLEMENTED, SHORT RSENSE1 & RSENSE2.

NOTE:

WHEN DCR SENSING IS

ITH2

R49

R49

R50

R50

OPT

OPT

OPERATION OPTIONAL DCR SENSING

ITH1

VFB1 VFB2

OPTIONAL JUMPERS FOR

SINGLE OUTPUT/DUAL PHASE

on PCB

Tooling Holes

OPT

OPT

R51

R51

VSW2 S2+

REMOVE R30, R29, R40 & R39

CALCULATE R45, R47, C14 AND

R51, R53 & C15 PER THE DATA

STUFF R61 AND R62 WITH 0 OHMS.

TRK/SS2TRK/SS1

R52

R52

OPT

OPT

D

1630 McCarthy Blvd.

Milpitas, CA 95035

Phone: [phone]

Fax: [phone]

1630 McCarthy Blvd.

Milpitas, CA 95035

Phone: [phone]

Fax: [phone]

1630 McCarthy Blvd.

Milpitas, CA 95035

Phone: [phone]

Fax: [phone]

VL2-

R62 OPTR62 OPT

TECHNOLOGY

TECHNOLOGY

TECHNOLOGY

S2-

R53

OPT

R53

OPT

OPT

OPT

DATE

DATE

DATE

APPROVALS

APPROVALS

APPROVALS

CONTRACT NO.

CONTRACT NO.

CONTRACT NO.

SHEET. ALSO REFER TO QSG

FOR EXAMPLE.

RUN2RUN1

R55

R55

OPT

OPT

OPT

OPT

1

1

1

REV

REV

REV

OF

OF

OF

8

SHEET

SHEET

SHEET

DC1185B

DC1185B

DC1185B

DWG NO

DWG NO

DWG NO

1185B-1.DSNNONE

1185B-1.DSNNONE

1185B-1.DSNNONE

FILENAME:

FILENAME:

FILENAME:

BUCK CONVERTER

BUCK CONVERTER

BUCK CONVERTER

7

CAGE CODE

CAGE CODE

CAGE CODE

SCH, LTC3850EUF, DUAL OUTPUT SYNCHRONOUS

SCH, LTC3850EUF, DUAL OUTPUT SYNCHRONOUS

SCH, LTC3850EUF, DUAL OUTPUT SYNCHRONOUS

SIZE

SIZE

SIZE

SCALE:

SCALE:

MIKE S. 08/05/13

CHECKED

APPROVED

ENGINEER

DESIGNER

CHECKED

APPROVED

ENGINEER

DESIGNER

CHECKED

APPROVED

ENGINEER

DESIGNER

47uF

COUT1/COUT4

R10

3.16K

SCALE:

Tuesday, September 10, 2013

Tuesday, September 10, 2013

Tuesday, September 10, 2013

6

100uF

5

2.55K

FSW

TITLE

TITLE

TITLE

10/31/06

10/31/06

10/31/06

MEI

MEI

MEI

DRAWN

DRAWN

DRAWN

SET RSENSE FILTER TIME CONSTANT0.6nH/RSENSE FOR 2010 PACKAGE.

NOTE:

4

JP3

JP3

CCMBM

3

2

MODE

MODE

PS

1

R4

10.0KR410.0K

INTVCC

INTVCCVIN

C1

OPTC1OPT

R10R1

Linear Technology has made a best effort to

Linear Technology has made a best effort to

Linear Technology has made a best effort to

0

E1E1

R27

[1]

R27

[1]

C37

OPT

C37

OPT

R7

10.0KR710.0K

R26

OPT

R26

OPT

1

2

RUN1

ON

SYNC

and reliable operation in the actual application, Component

Applications Engineering for assistance.

and reliable operation in the actual application, Component

Applications Engineering for assistance.

and reliable operation in the actual application, Component

Applications Engineering for assistance.

Customer Notice:

Customer Notice:

Customer Notice:

design a circuit that meets customer-supplied specifications;

however, it remains the customer's responsibility to verify proper

substitution and printed circuit board layout may significantly

affect circuit performance or reliability. Contact Linear

This circuit is proprietary to Linear Technology and supplied

for use with Linear Technology parts.

design a circuit that meets customer-supplied specifications;

however, it remains the customer's responsibility to verify proper

substitution and printed circuit board layout may significantly

affect circuit performance or reliability. Contact Linear

This circuit is proprietary to Linear Technology and supplied

for use with Linear Technology parts.

design a circuit that meets customer-supplied specifications;

however, it remains the customer's responsibility to verify proper

substitution and printed circuit board layout may significantly

affect circuit performance or reliability. Contact Linear

This circuit is proprietary to Linear Technology and supplied

for use with Linear Technology parts.

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 representa­tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

VIN

4.7uF

4.7uF

CMDSH-3D1CMDSH-3

VINF

20

BG1

ITH1

C2

R2

0

D2

C11

C11

0.1uF

0.1uF

C17

C17

R18 2.2R18 2.2

INTVCC

19

18

17

VIN

BG2

INTVCC

ITH2

VFB2

VFB1

R32 20.0KR32 20.0K

R33 20.0KR33 20.0K

C43 100pFC43 100pF

C42

100pF

C42

100pF

R31

[1]

R31

[1]

0.1uFC20.1uF

OPTR2OPT

VOUT1

16

PGND

6

TRK/SS2

C44

C44

R35

R35

R34

R34

R250R25

15

9

RUN2

1nF

1nF

0

BOOST2

RUN2

OPT

OPT

CMDSH-3D2CMDSH-3

13

14

TG2

SW2

ILIM10EXTVCC11PGOOD

VIN

[1]

[1]

R36 0R36 0

E10E10

TRK/SS2

C21

C21

S2+

8

12

C47

C47

R37

R37

0.1uF

0.1uF

C15

C15

7

SENSE2+

0.1uF

0.1uF

OPT

OPT

SENSE2-

SGND

R38

R38

R40

100

R40

100

1nF

1nF

S2-

R39

100

R39

100

29

R43

[1]

R43

[1]

C49

OPT

C49

OPT

R44

OPT

R44

OPT

R42

OPT

R42

OPT

R41

OPT

R41

OPT

INTVCC

C48

OPT

C48

OPT

3

JP2JP2

OFF

E2E2

RUN2

OPT

OPT

1ON2

GND

INTVCC

EXTVCC

E3E3

R46

R46

C50

1uF

C50

1uF

EXTVCC

INTVCCVINF

R60

OPT

R60

OPT

STUFF R60 WITH 0 OHMS FOR

100K

100K

PGOOD

E4E4

PGOOD

4.6V<VIN<5.5V

NOTE:

D1

C20

0.1uF

C20

0.1uF

R30

100

R30

100

C14

1nF

C14

1nF

R9 0R9 0

S1+

S1-

R29

100

R29

100

27

23

28

22

21

TG1

SW1

BOOST1

SENSE1-

SENSE1+

U1

U1

LTC3850EUF

LTC3850EUF

TRK/SS11ITH12VFB13VFB24ITH25TRK/SS2

MODE24FREQ

RUN1

25

26

TRK/SS1

RUN1

C12

1nF

C12

1nF

0

[1]

[1]

R80R8

R10

R10

R28

OPT

R28

OPT

C38

OPT

C38

OPT

3

JP1JP1

OFF

C41 1nFC41 1nF

R30R3

E9E9

TRK/SS1

&

8.66K

5.9K

ITH1 ITH2

R43

25.5K

10.0K

4

30.1K

17.8K

VOUT1 VOUT2

TOP FEED BACK R

RENESAS RJK0330DPB

3

RENESAS RJK0305DPB RENESAS RJK0330DPB

RENESAS RJK0305DPB

0.4uH

2

TOKO FDU0650-R56M=P3

0.003

0.002 VITEC 59PR9875

1.8V/10A

1.2V/15A

VOUT1

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

AND COUT4.

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

2. FSW = 400kHz For Assy - B

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

1. FSW = 500kHz For Assy - A

2.0V/10A

- A

1.5V/15A

- B

1

[1]

dc1185b-a/-bf

9

DEMO MANUAL
DC1185B-A/-B

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 LTC applica­tion engineer.

Mailing Address:

Linear Technology

1630 McCarthy Blvd.

Milpitas, CA 95035

Copyright © 2004, Linear Technology Corporation

Linear Technology Corporation

10

1630 McCarthy Blvd., Milpitas, CA 95035-7417

[phone] ● FAX: [phone] ● www.linear.com

dc1185b-a/-bf

LT 1213 • PRINTED IN USA

 LINEAR TECHNOLOGY CORPORATION 2013

Mouser Electronics

Authorized Distributor

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