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 2006 Semtech Corp.

www.semtech.com

SC1486A

POWER MANAGEMENT

Application Information (Cont.)

Layout Guidelines (Cont.)

The layout can be considered in two parts, the control section referenced to VSSA1/2 and the power section.

Looking at the control section first, locate all components referenced to VSSA1/2 on the schematic and place

these components at the chip. Connect VSSA1 and VSSA2 using either a wide (>0.020”) trace or a copper pour if

room allows. Very little current flows in the chip ground therefore large areas of copper are not needed.

U1

SC1486A

3

1

23

6

7

5

4

22

27

24

26

25

28

17

15

9

20

21

19

18

13

12

8

10

11

14

2

16

VDDP1

PGND1

TON1

DH1

BST1

LX1

ILIM1

EN/PSV1

PGD1

VOUT1

FB1

VCCA1

VSSA1

VDDP2

PGND2

TON2

DH2

BST2

LX2

ILIM2

PGD2

FB2

REFIN

REFOUT

VCCA2

VSSA2

DL1

DL2

PWR_SRC

PWR_SRC

5VSUS

VCCA2

5VRUN

R10

45k3

C21

1u

0402

C18

1u

VCCA1

PGD1

REFOUT

0402

C9

1u

R2 10R

0402

R3

1M

0603

0402

1.8V

C20

1n

0603

VCCA2

0402

C22

1u

0402

C17

27p

0402

0402

1.8V

C8

1u

R9 10k0

0402

VCCA1

TON1

R1 10R

R11 10R

0.9V

R4

649k

0603

C23

1n

R13

17k4

0402

VSSA2

0603

C19

0u1

VSSA1

TON2

R12

10k0

0603

VCCA1

0402

PGD2

0402

Figure 7: Components Connected to VSSA1 and VSSA2

Figure 8: ExampleVSSA Copper Pours (Left) and 0.020” Traces (Right)