FAN5665 Fairchild Semiconductor, FAN5665 Datasheet - Page 13

• Manufacturer Part Number: FAN5665
• Description: The FAN5665 is a 5V switched capacitor step-up DC/DC converter with an input voltage range from 2
• Manufacturer: Fairchild Semiconductor

© 2007 Fairchild Semiconductor Corporation
FAN5665 • Rev. 1.0.1
Applications Information
LED Driver
The FAN5665 can be configured as an LED driver, as
shown in Figure 41. The constant current is generated
by putting a resistor in series with the LED. The value of
series resistor is dictated by the current through the
LED. The maximum current that the FAN5665 can
deliver is 30mA. The number of parallel branches and
current through LEDs should be chosen according to
the maximum output current.
2.2µF
C
IN
0.22µF
C2
Figure 41. LED Driver Example Circuit
VIN
GND
C2-
C2+
VOUT
C1+
C1-
EN
Enable
0.22µF
C1
2.2µF
C
OUT
(Continued)
R
S
V
OUT
=5V
R
S
13
PCB Layout
The PCB layout should be designed carefully due to the
high switching frequency and corresponding transient
currents.
connected very close to the pins of the IC. A clean
board layout with a good ground plane ensures proper
operation of the device. A PCB recommendation for a
two-layer board is shown in Figure 42. Note that the
bottom layer is a dedicated ground plane.
All
the
Figure 42. PCB Layout
external
capacitors
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should be