CM9320 Datasheet, PDF (9/10 Pages) California Micro Devices Corp – Asymmetrical High Efficiency Two Channel Boost LED Driver

PRELIMINARY
CM9320
Application Information (cont’d)
In this case, because of small input ripple, the effi-
ciency is about 2% higher.
to V_IN
CM9320
7
GND
VIN ⁶
R_F
100
C_F
0.1 uF/10V
Figure 2. Input Filter Solution
Layout Guide
Components should be placed as close as practical to
the IC to assure good performance. The input and out-
put capacitors should be close, with minimum trace
resistance and inductance. Reflected input ripple
depends on the impedance of the VIN source, such as
the PCB traces and the Li-ion battery, which have ele-
vated impedance at higher frequencies. The input
capacitor located near the converter input reduces this
source impedance and ripple. Any ESR from the
capacitor will result in steps and spikes in the ripple
waveform, and possibly produce EMI.
Route any noise sensitive traces away from the switch-
ing power components. Place the inductor and diode
as close as possible to the SW pin to prevent noise
emissions.
The ground connections for RSET(1,2) resistors
should be kept separate from the high power grounds
and connect directly to the ground pin to assure accu-
rate current and voltage settings. For better heat flow,
connect all NC pins to GND plane. Also connect the
thermal landing to the bottom ground plane with ther-
mal vias.
Figure 3. Example CM9320 PC Layout and
Component Placement for Standard Application
© 2006 California Micro Devices Corp. All rights reserved.
05/08/06 490 N. McCarthy Blvd., Milpitas, CA 95035-5112 l Tel: [phone] l Fax: [phone] l www.cmd.com
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