8

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POWER MANAGEMENT

SC191

Table 3: Recommended Capacitors

Manufacturer

Part Number

Value

(μF)

Rated Voltage

(VDC)

Temperature

Coefficient

Package Size

Murata

GRM-188R60J475KE19D

4.7

6.3

X5R

0603

Murata

GRM-188R60G106ME47D

10

4

X5R

0603

TDK

C1608X5R0G106M

10

4

X5R

0603

PCB Layout Considerations

Poor layout can degrade the performance of the DC-DC

converter and can be a contributory factor in EMI prob-

lems, ground bounce and resistive voltage losses. Poor

regulation and instability can result. A few simple design

rules can be implemented to ensure good layout:

1) Place the inductor and filter capacitors as close to the

device as possible and use short, wide traces between

the power components.

2) Route the output voltage feedback path away from in-

SC191

VOUT

VIN

GND

Vias to GND

Plane

LX

GND

ductor and LX node to minimize noise and magnetic inter-

ference. Use a ground plane to further reduce noise.

3) Maximize ground metal on the component side to

improve the return connection and thermal dissipation.

Separation between the LX node and GND should be

maintained to avoid coupling of switching noise to the

ground plane.

4) To further reduce noise interference on sensitive circuit

nodes, use a ground plane with several vias connecting

all ground planes together.

Applications Information (Cont.)

Suggested Layout