• Built-In Open Circuit Protection
• Over Voltage Protection
• Efficiency Up to 83% at VIN=4.2V, 3LEDs, ILED=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
• SOT23-6 and TSOT23-6 Packages

• Cellular Phones
• PDAs
• DSCs
• Handheld Devices
• White LED Display Backlighting

AIC3643 is a current-mode pulse-widthmodulation (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 SOT23-6 and TSOT23-6 packages.