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 2004 Semtech Corp.

www.semtech.com

SC4605

POWER MANAGEMENT

Applications Information (Cont.)

Design Example 3: 3.3V to 1.5V @ 15A application with SC4605 and its typical efficiency characteristics.

Efficiency vs Load current

0.88

0.89

0.9

0.91

0.92

0.93

36

9

12

15

Load current (A)

Vin=3.3V

Vo=1.5V

R3

2.43k

U2

J12

Vout

1

Vout

2

Vout

3

GND

4

GND

5

GND

6

GND

7

GND

8

GND

9

Vout

10

Vout

11

Vout

12

U3

J8

Vin

1

Vin

2

Vin

8

Vin

7

GND

3

GND

4

GND

5

GND

6

C3

4.7u

C2 2.2n

R1

15.8k

C7

470u

C1

270p

C18

0.1u

D2

HC 2-2R 2

2.2u

C5

22u

C4

22u

C17

1u

M11

4 x Si78 82

Vo u t= 1 .5V 15 A

M12

M22

C10

330u

M21

C9

8.2n

R8

115

R7

5.62k

R9

6.49k

R6

1

R5

1

C16

470pF

U1

S C 4605

VCC

2

ISET

3

COMP

4

FSET

5

BST

1

DRVH

10

DRVL

8

VSENSE

6

GND

7

PHASE

9

C12

22u

C13

22u

C14

22u

C11

330u

Vin= 3.3V

R13

1

R3

2.43k

U2

J12

Vout

1

Vout

2

Vout

3

GND

4

GND

5

GND

6

GND

7

GND

8

GND

9

Vout

10

Vout

11

Vout

12

U3

J8

Vin

1

Vin

2

Vin

8

Vin

7

GND

3

GND

4

GND

5

GND

6

C3

4.7u

C2 2.2n

R1

15.8k

C7

470u

C1

270p

C18

0.1u

D2

HC 2-2R 2

2.2u

C5

22u

C4

22u

C17

1u

M11

4 x Si78 82

Vo u t= 1 .5V 15 A

M12

M22

C10

330u

M21

C9

8.2n

R8

115

R7

5.62k

R9

6.49k

R6

1

R5

1

C16

470pF

U1

S C 4605

VCC

2

ISET

3

COMP

4

FSET

5

BST

1

DRVH

10

DRVL

8

VSENSE

6

GND

7

PHASE

9

C12

22u

C13

22u

C14

22u

C11

330u

Vin= 3.3V

R13

1