DC664A - ANALOG DEVICES - Datasheet.Live

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 664

2-PHASE DUAL STEP-DOWN CONVERTER WITH OUTPUT TRACKING

1

LTC3737EUF

DESCRIPTION

Demonstration circuit 664 is a high efficiency 2-phase

dual step-down DC/DC converter with 2.75V to 9.8V

input range. It has two outputs: 2.5V/2.5A and

1.8V/3A. The demo board features the constant fre-

quency current mode LTC®3737EUF controller. The

MOSFET V

DS

sensing eliminates the need for sense

resistors and improves efficiency. Out of phase op-

eration significantly reduces input ripple current and

noise as well as the input capacitor size.

Switching frequency is internally set at 550KHz. For

noise sensitive applications, the converter can be ex-

ternally synchronized from 250KHz to 850KHz. The

frequency can also be selected with PLLLPF pin. Ty-

ing PLLLPF pin to GND selects 300KHz operation;

tying PLLLPF pin to VIN selects 750KHz operation.

The demo board has tracking function, allowing V

OUT2

to track V

OUT1

during start-up.

Design files for this circuit board are available. Call

the LTC factory.

LTC is a trademark of Linear Technology Corporation

Table 1.

Performance Summary (TA = 25°C)

PARAMETER CONDITION VALUE

Input Voltage Range 2.75V to 9.8V

V

OUT1

V

IN

= 2.75V to 9.8V, I

OUT1

= 0A to 2.5A,

I

OUT2

= 0A to 3A

2.5V ±3%

V

OUT2

V

IN

= 2.75V to 9.8V, I

OUT1

= 0A to 2.5A,

I

OUT2

= 0A to 3A

1.8V ±3%

Typical Output Ripple V

OUT1

V

IN

= 3.3V, I

OUT1

= 2.5A (20MHz BW) 14mV

P–P

Typical Output Ripple V

OUT2

V

IN

= 3.3V, I

OUT2

= 3A (20MHz BW) 19mV

P–P

Typical Switching Frequency PLLLPF Pin Floating 550kHz

QUICK START PROCEDURE

Demonstration circuit 664 is easy to set up to evalu-

ate the performance of LTC3737. 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 out-

put 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.

With power off, connect the input power supply to

+Vin (2.75V-9.8V) and GND (input return).

2.

Connect the 2.5V load (Load 1 in Figure 1) between

Vout1 and GND; connect the 1.8V load (Load 2 in

Figure 1) between Vout2 and GND. (Initial loads:

0A.)

3.

Connect the DVMs to the input and outputs.

4.

Turn on the input power supply and check for the

proper output voltages. Vout1 should be 2.5V+/-

3%. Vout2 should be 1.8V+/-3%.

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 664

2-PHASE DUAL STEP-DOWN CONVERTER WITH OUTPUT TRACKING

2

5.

Once the proper output voltages are established,

adjust the loads within the operating range and ob-

serve the output voltage regulation, ripple voltage

and other parameters.

Figure 1. Proper Measurement Equipment Setup

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 664

2-PHASE DUAL STEP-DOWN CONVERTER WITH OUTPUT TRACKING

3

Figure 2. Scope Probe Placement for Measuring Input or Output Ripple

Figure 3. Efficiency vs Load Current (Burst Mode, 550kHz)

40

50

60

70

80

90

100

1 10 100 1k 10k

LOAD CURRENT (mA )

Vin=3.3V

Vo=2.5V

Vo=1.8V

A

B

C

D

E

4 4

3 3

2 2

1 1

NOTES:

UNLESS OTHERWISE SPECIFIED

Mode

Burst

1.8V at 3A

(Opt.)

(Opt.) (Opt.)

Circuit That Meets Customer-Supplied Specifications;

LTC CONFIDENTIAL - FOR CUSTOMER USE ONLY

Linear Technology Has Made A Best Effort To Design A

Supplied For Use With Linear Technology Parts.

This Circuit Is Proprietary To Linear Technology And

Circuit Board Layout May Significantly Affect Circuit

Applications Engineering For Assistance.

Application. Component Substitution And Printed

However, It Remains The Customer's Responsibility To

Performance Or Reliability. Contact Linear Technology

Verify Proper And Reliable Operation In The Actual

Customer Notice

Pusle Skipping

2.5V at 2.5A

DEMO CIRCUIT 664A LTC3737EUF

LTC3737EUF 2-Phase Dual Step-Down DC/DC Converter

LINEAR TECHNOLOGY CORPORATION

1630 McCARTHY BLVD.

MILPITAS, CA. 95035

408-432-1900

408-434-0507 FAX

1 1Monday, May 17, 2004

Title

Size Document Number Rev

Date: Sheet of

VIN

R4

187K

1%

C20

10uF

10V

R1

10

R12

10K

R2

1M

C15

(Opt.)

C12

100pF

C17

( Opt. )

Q1

Si9803DY

3

1

2

4

5

6

7

8

C1

22uF

10V

Vout2

Gnd

Q2

Si9803DY

3

1

2

4

5

6

7

8

C2

22uF

10V

Gnd

C7

10uF

6.3V

U1

LTC3737EUF

5

8

23 2

3

4

7

9

6

10

11

12

16

15

14

13

17

18

19

20

21

22

1

24

25

VIN

ITH2

IPRG1 IPRG2

PLLLPF

SGND

VFB2

PGOOD

TRACK

SW2

SENSE2+

PVIN2

PGND

TG2

RUN/SS

N/C

TG1

SYNC/MODE

N/C

PVIN1

SENSE1+

SW1

ITH1

VFB1

PGND

R13

10K

Gnd

C14

(Opt.)

Q4

FDC602P

3

1

2

4

5

6

SGnd R9

(Opt.)

Vin

2.75V - 9.8V

C11

(Opt.)

L2

1.5uH

IHLP-2525CZ-01

Q3

FDC602P

3

1

2

4

5

6

C13

220pF

R6

59K

1%

+

C9

150uF

4V

Sanyo

R8

(Opt.)

C18

(Opt.)

R10

59K

1%

R3

118K

1%

C8

10uF

6.3V

R11

10K

C3

1uF

10V

R5

118K

1%

IPRG1

JP1

1

2

3

C10

0.01uF

RUN/SS

+

C6

150uF

4V

Sanyo

SYNC/MODE

IPRG2

L1

1.5uH

IHLP-2525CZ-01

C16

(Opt.)

Vout1

PLLLPF

D1

SBM540

1

3

2

C19

10uF

10V

PGOOD

R7

59K

1%

D2

SBM540

1

3

2

Linear Technology Corporation

LTC3737EUF

Bill Of Material

Demo Bd. # 664A

6/20/2005

8:33 AM

Item Qty Reference Part Description Manufacture / Part #

1 4 C12,C13,C16,C18 CAP., X7R, 100pF 50V AVX, 04025C101MAT 0402

2 2 C11,C14 CAP., X7R, 220pF 50V AVX, 04025C221MAT 0402

3 1 C10 CAP., X7R, 0.01uF 25V AVX, 04023C103MAT 0402

4 1 C3 CAP., X5R, 1uF 10V TAIYO YUDEN, LMK107BJ105MA 0603

5 2 C7,C8 CAP., X7R, 10uF 6.3V TAIYO TUDEN, JMK316BJ106ML 1206

6 2 C19,C20 CAP., X5R, 10uF 10V TDK, C3216X5R1A106KT 1206

7 1 C1 CAP., X7R, 22uF 10V TAIYO YUDEN, LMK432BJ226MM 1812

8 2 C6,C9 CAP., POSCAP, 150uF, 4V SANYO, 4TPB150MC C-CASE

9 0 C2,C15,C17 OPTION

10 2 D1,D2 DIODE, SCHOTTKY BARRIER RECTIFIER DIODE INC., SBM540 POWERMITE-3

11 7 E6-E11,E13 TURRET, TEST PIN, .061" MILL-MAX 2308-2-00-44

12 6 E1-E5,E12 TURRET, TEST PIN, .095" MILL-MAX 2501-2

13 1 JP1 JUMPER, 0.079"CC, 3PIN COMM CON, 2802S-03G1

14 1 JP1 SHUNT COMM CON, CCIJ2MM-138G

15 2 L1,L2 INDUCTOR, 1.5uH VISHAY, IHLP-2525CZ-01-1.5

16 0 Q1,Q2 ( OPTIONAL ) P-CHANNEL FAST SWITCHING MOSFET VISHAY, Si9803DY SO8

17 2 Q3,Q4 P-CHANNEL POWERTRENCH MOSFET FAIRCHILD, FDC602P SUPERSOT-6

18 1 R1 RES., CHIP, 10 1/16W 5% AAC, CR05-100JM 0402

19 3 R11,R12,R13 RES., CHIP, 10K 1/16W 5% AAC, CR05-103JM 0402

20 2 R8,R9 RES., CHIP, 15K 1/16W 5% AAC, CR05-153JM 0402

21 3 R6,R7,R10 RES., CHIP, 59K 1/16W 1% AAC, CR05-5902FM 0402

22 1 R2 RES., CHIP, 100K 1/16W 5% AAC, CR05-104JM 0402

23 2 R3,R5 RES., CHIP, 118K 1/16W 1% AAC, CR05-1183FM 0402

24 1 R4 RES., CHIP, 187K 1/16W 1% AAC, CR05-1873FM 0402

25 1 U1 I.C., LTC3737EUF LINEAR, LTC3737EUF QFN24

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