
August 2005
FAN5331
High Ef?ciency Serial LED Driver and OLED Supply with
20V Integrated Switch
Features
Description
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1.6MHz Switching Frequency
Low Noise
Low R DS(ON) : 0.5 ?
Adjustable Output Voltage
1A Peak Switch Current
1W Output Power Capability
Low Shutdown Current: <1μA
Cycle-by-Cycle Current Limit
Over-Voltage Protection
Fixed-Frequency PWM Operation
Internal Compensation
5-lead SOT-23 Package
The FAN5331 is a general purpose, ?xed-frequency boost con-
verter designed to operate at high switching frequencies in
order to minimize switching noise measured at the battery ter-
minal of hand-held communications equipment. Quiescent cur-
rent in normal mode of operation as well as in shutdown mode
is designed to be minimal in order to extend battery life. Normal
mode of operation or shutdown mode can be selected by a logic
level shutdown circuitry.
The low ON-resistance of the internal N-channel switch ensures
high ef?ciency and low power dissipation. A cycle-by-cycle cur-
rent limit circuit keeps the peak current of the switch below a
typical value of 1A. The FAN5331 is available in a 5-lead SOT-
23 package.
Applications
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Cell Phones
PDAs
Handheld Equipment
Display Bias
LED Bias
Typical Application
V IN
C IN
2.7V to 5.5V
L
10μ H
BAT54
C OUT
V OUT
4.7 μ F
4.7 μ F
5
V IN
SW
1
R1
C F
120pF
FB
3
R2
ON
OFF
4
SHDN
GND
2
Figure 1. Typical Application Diagram
?2004 Fairchild Semiconductor Corporation
FAN5331 Rev. 1.0.1
1
www.fairchildsemi.com