AIC1648
Built-in OVP White LED Step-Up Converter
ꢀFEATURES
ꢀDESCRIPTION
Built-In Open Circuit Protection
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AIC1648 is a fixed frequency step-up DC/DC
Over Voltage Protection
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converter designed to drive white LEDs with a
Efficiency Up to 84% at VIN=4.2V, 3LEDs,
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constant current to provide backlight in hand-
held devices. Series connection of LEDs
provides identical LED currents resulting in
uniform brightness. This configuration eliminates
the need of ballast resistors. The built-in open
load protection prevents the damage resulting
from an open circuit condition. Low 95mV
feedback voltage minimizes power loss in the
current setting resistor for better efficiency.
I
LED=20mA
1.2MHz Fixed Switching Frequency
Drives Up to 5LEDs in series
Low Supply Current: 70µA
Matches LED Current
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Requires Tiny Inductor and Capacitors
Tiny SOT-23-6 Package
ꢀAPPLICATIONS
AIC1648 is a step-up PWM converter, which
includes an internal N-channel MOSFET switch
for high efficiency. The high switching frequency,
1.2MHz, allows the use of tiny external
components.
Cellular Phones
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PDAs
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DSCs
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Handheld Devices
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White LED Display Backlighting
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AIC1648 is available in a space-saving, 6-lead
SOT-23-6 package.
TYPICAL APPLICATION CIRCUIT
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90
D1
3.3~4.2V
L
V
=4.2V
IN
6.8µH
85
80
75
70
65
60
C2
C1
1µF
1µF
VIN
SW
V
=3.6V
IN
SHDN
GND
OVP
FB
V
=3.0V
IN
20mA
AIC1648
µ
3 LEDs, 6.8 H
L1: 976AS-6R8M, TOKO
D1: RB521S-30, ROHM
R
L1: 976AS-6R8M/D321F, TOKO
D1: RB521S-30, ROHM
C1: JMK107BJ105KA, TAIYO YUDEN
C2: EMK212BJ105KA, TAIYO YUDEN
FB
4.7Ω
0
5
10
LED Current (mA)
15
20
Fig. 1 Li-Ion Powered Driver for Three White LEDs
Analog Integrations Corporation
Si-Soft Research Center
DS-1648P-03 010405
3A1, No.1, Li-Hsin Rd. I, Science Park, Hsinchu 300, Taiwan, R.O.C.
TEL: 886-3-5772500
FAX: 886-3-5772510
www.analog.com.tw
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