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 2005 Semtech Corp.

www.semtech.com

SC470

POWER MANAGEMENT

The layout can be considered in two parts, the control section referenced to VSSA and the power section. Looking

at the control section first, locate all components referenced to VSSA on the schematic and place these components

at the chip. Connect VSSA 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.

C10

1uF

R3

20k0

R7

20k0

EN/PSV

1

TON

2

VOUT

3

VCCA

4

FB

5

PGD

6

VSSA

7

PGND

8

DL

9

VDDP

10

ILIM

11

LX

12

DH

13

BST

14

U1

SC470

VOUT

C8

1nF

R1

1M

5VSUS

PGOOD

VBAT

C9

1uF

5VSUS

R2

10R

0402

0402

0402

0402

C5

56p

0402

R5 49k9

0402

VOUT SWITCH (1)

0603

0402

0603

Figure 9: Components Connected to VSSA

Figure 10: Example VSSA 0.020” Traces

Application Information (Cont.)

In Figure 10 above, all components referenced to VSSA have been placed and have been connected using 0.020”

traces. Decoupling capacitors C9 and C10 are as close as possible to their pins. C9 should connect to the ground

plane using two vias