The AP3605 is a step-up DC/DC converter based on 1.5x charge pump current source, it is specially designed for °C supplies in backlight display. The AP3605 can provide constant current up to 20mA for each °C, which is programmed by an external resistor, so it has a total capability to provide 80mA for 4 °Cs. The chip has a good performance of °C current matching and allows PWM brightness dimming control. Additionally, high switching frequency up to 1MHz enables the use of two small external flying capacitors. Internal soft-start circuitry prevents excessive inrush current during start-up. The AP3605 supply voltage range is from 2.7V to 5.5V, ideally suited for applications powered by the Liion battery. The AP3605 is available in a 3mmx3mm QFN-3x3-16 tiny package. Its operating temperature range is -40oC to 85oC.