AIC1648 Datasheet, PDF (1/10 Pages) Analog Intergrations Corporation – Built-in OVP White LED Step-Up Converter

AIC1648
Built-in OVP White LED Step-Up Converter
FEATURES
Built-In Open Circuit Protection
Over Voltage Protection
Efficiency Up to 84% at V_IN=4.2V, 3LEDs,
I_LED=20mA
1.2MHz Fixed Switching Frequency
Drives Up to 5LEDs in series
Low Supply Current: 70µA
Matches LED Current
Requires Tiny Inductor and Capacitors
Tiny SOT-23-6 Package
APPLICATIONS
Cellular Phones
PDAs
DSCs
Handheld Devices
White LED Display Backlighting
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.
TYPICAL APPLICATION CIRCUIT
3.3~4.2V
L
D1
6.8µH
C1
1µF
VIN SW
SHDN _OVP
GND _FB
AIC1648
L1: 976AS-6R8M/D321F, TOKO
D1: RB521S-30, ROHM
C1: JMK107BJ105KA, TAIYO YUDEN
C2: EMK212BJ105KA, TAIYO YUDEN
90
85
C2
1µF
80
75
20mA
70
R_FB
65
4.7Ω
60
0
VIN=4.2V
VIN=3.0V
VIN=3.6V
3 LEDs, 6.8µH
L1: 976AS-6R8M, TOKO
D1: RB521S-30, ROHM
5
10
15
20
LED Current (mA)
Fig. 1 Li-Ion Powered Driver for Three White LEDs
Analog Integrations Corporation
Si-Soft Research Center
3A1, No.1, Li-Hsin Rd. I, Science Park, Hsinchu 300, Taiwan, R.O.C.
TEL: [phone]
FAX: [phone] www.analog.com.tw
DS-1648P-03 010405
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