AIC1843 Datasheet, PDF (1/14 Pages) Analog Intergrations Corporation – High Efficiency 1.5X charge Pump For White LEDs Backlighting

AIC1843
High Efficiency 1.5X charge Pump
For White LEDs Backlighting
FEATURES
1MHz Switching Frequency
2.7V to 5.5V Input Voltage Range
Low Shutdown Current: ≦1µA
Regulated 20mA Full-Scale Output Current
32-Position Linear Scale with Digital Control
High Accuracy Brightness Matching
33% Less Input Current Than Doubler Charge
Pump
No Inductors Required
Build-in Soft-Start
Current Limit and Over Temperature Protection
12-Pin DFN Package
APPLICATIONS
Cellular Phones
PDAs
Digital Still Cameras
Handheld Devices
White LED Backlighting
GENERAL DESCRIPTION
The AIC1843 provides 4 LED current source
outputs with regulated constant current for uniform
intensity. The AIC1843 is the low noise, constant
frequency charge pump DC/DC converter that
uses 1.5X conversion to increase efficiency in
white LED applications. The devices can be used
to produce current levels up to 20mA for each
output from a 2.7V to 5.5V input. Low external
parts counts (two 1μF flying capacitors and two
small bypass capacitors at V_IN, and OUT) make
the AIC1843 ideal for small, battery-powered
applications.
EN/SET interface is used to enable, disable and
set the LED current for a 32 level logic scale LED
brightness control. Built-in current limiting, with
thermal shutdown provides protection to the
AIC1843 against fault conditions. Automatic soft-
start circuitry prevents excessive inrush current
during start-up. 1MHz high switching frequency is
enable to use tiny external components.
The AIC1843 is available in a 12-pin thin DFN
package.
TYPICAL APPLICATION CIRCUIT
CFLY1
1uF
U1
C1+
C2+
C1-
C2-
EN/SET
EN/SET
D1
Vin=2.7V~5.5V
VIN
D2
Cin
1uF
OUT
D3
Cout
1uF
GND
D4
AIC1843
CFLY2
1uF
Analog Integrations Corporation 3A1, No.1 Li-Hsin Rd. I, Science Park, Hsinchu 300, Taiwan
TEL: [phone]
FAX: [phone] www.analog.com.tw
DS-1843G-03 080907
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