SC441A

7

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Layout Guidelines

The SC44A contains a boost converter and the place-

ments of the power components outside the SC44A

should follow the layout guidelines of a general boost

converter. The evaluation application circuit on page 7

will be used as an example. C2 and C3 are input decou-

pling capacitor for SC44A VIN pin and main power input.

C2,C3 should be placed as close as possible to the VIN pin

to achieve the best decoupling performance.

To minimize the switching noise, The switching loop

formed by input decoupling capacitors, internal switch,

output Schottky diode and output capacitors must be

minimized. The LED current programming resistor(R6),

compensation network (R9,C5,C7) and soft start capacitor

(C6) should be placed as close as possible to SC44A. The

C4~C7 are decoupling capacitors for LED current source

which prevent IO pins from noise influence. C4~C7

should be placed close to each corresponding IO pin.

Use an isolated local AGND plane underneath the con-

troller and tie it to the negative side of output capacitor

through R4 for better noise immunity.

Applications Information (continued)