ADP1649ACBZ-R7 datasheet(27/28 Pages) AD

27 / 28 page

Data Sheet

ADP1649

Rev. 0 | Page 27 of 28

PCB LAYOUT

Poor layout can affect performance, causing electromagnetic

interference (EMI) and electromagnetic compatibility (EMC)

problems, ground bounce, and power losses. Poor layout can

also affect regulation and stability. Figure 42 shows an optimized

layout implemented using the following guidelines:

•

Place the inductor, input capacitor, and output capacitor

close to the IC using short tracks. These components carry

high switching frequencies and large currents.

•

Route the trace from the inductor to the SW pin, providing

as wide a trace as possible. The easiest path is through the

center of the output capacitor.

•

Route the LED_OUT path away from the inductor and the

SW node to minimize noise and magnetic interference.

•

Maximize the size of ground metal on the component side

to help with thermal dissipation.

•

Use a ground plane with two to three vias connected to the

component side ground near the output capacitor to

reduce noise interference on sensitive circuit nodes.

Analog Devices applications engineers can be contacted

through the Analog Devices sales team to discuss different

layouts based on system design constraints.

Figure 42. Layout of the ADP1649 Driving a High Power White LED (WLCSP)

DIGITAL

INPUT/

OUTPUT

Li-ION +

PGND

INDUCTOR

LED

ANODE

AREA = 16.4mm2

ADP1649ACBZ-R7 Datenblatt(PDF) 27 Page - Analog Devices