AIC1648
Built-in OVP White LED Step-Up Converter


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.
null FEATURES
null Built-In Open Circuit Protection
null Over Voltage Protection
null Efficiency Up to 84% at VIN=4.2V, 3LEDs,
I
LED
=20mA
null 1.2MHz Fixed Switching Frequency
null Drives Up to 5LEDs in series
null Low Supply Current: 70µA
null Matches LED Current
null Requires Tiny Inductor and Capacitors
null Tiny SOT-23-6 Package


null APPLICATIONS
null Cellular Phones
null PDAs
null DSCs
null Handheld Devices
null White LED Display Backlighting
null DESCRIPTION
AIC1648 is a fixed frequency step-up DC/DC
converter designed to drive white LEDs with a
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.
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.
AIC1648 is available in a space-saving, 6-lead
SOT-23-6 package.


null
TYPICAL APPLICATION CIRCUIT

L
6.8µH
D1
SW
VIN
OVP
SHDN
FB
GND
AIC1648
3.3~4.2V
R
FB

4.7Ω
C1
1µF
C2
1µF
20mA
L1: 976AS-6R8M/D321F, TOKO
D1: RB521S-30, ROHM
C1: JMK107BJ105KA, TAIYO YUDEN
C2: EMK212BJ105KA, TAIYO YUDEN
LED Current (mA)
Ef
fi
ci
e
n
cy (
%
)

0510 15 20
60
65
70
75
80
85
90
V
IN
=3.6V
V
IN
=4.2V
V
IN
=3.0V
3 LEDs, 6.8µH
L1: 976AS-6R8M, TOKO
D1: RB521S-30, ROHM



Fig. 1 Li-Ion Powered Driver for Three White LEDs

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