AIC3643 Datasheet, PDF (1/13 Pages) Analog Intergrations Corporation – Built-in OVP White LED Step-Up Converter

AIC3643
Built-in OVP White LED Step-Up Converter
FEATURES
Built-In Open Circuit Protection
Over Voltage Protection
Efficiency Up to 83% at V_IN=4.2V, 3LEDs,
I_LED=20mA
1.2MHz Fixed Switching Frequency
Drives Up to 5LEDs in series
2.5V to 5.5V Input Voltage
Low Supply Current: 150μA
Matches LED Current
Requires Tiny Inductor and Capacitors
TSOT-23-6, and SOT-23-6 Packages
APPLICATIONS
Cellular Phones
PDAs
DSCs
Handheld Devices
White LED Display Backlighting
DESCRIPTION
AIC3643 is a current-mode pulse-width-
modulation (PWM), 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. Also low 100mV feedback
voltage minimizes power loss in the current
setting resistor for better efficiency.
AIC3643 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.
AIC3643 is available in a space-saving TSOT-
23-6, and SOT-23-6 packages.
TYPICAL APPLICATION CIRCUIT
3.0~4.2V
L
D1
6.8μH
C1
1μF
VIN SW
SHDN _OVP
GND _FB
AIC3643
L1: GTSD31-6R8M, GOTREND
D1: SS0540, PAN JIT
C1: JMK107BJ105KA, TAIYO YUDEN
C2: GRM21BR61C335K, MURATA
90
85
C2
3.3μF ₈₀
75
20mA
70
R_FB
65
5Ω
60
0
V =4.2V
IN
V =3.6V
IN
V =3V
IN
3 LEDs, 6.8μH
L1: GTSD31-6R8M, GOTREND
D1: SS0540, PAN JIT
Test Circuit refer to Fig.1
5
10
15
20
25
30
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-3643G-01 20090820
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