The LM3535 device is a highly integrated LED driver capable of driving 8 LEDs in parallel for large display applications. Independent LED control allows selection of a subset of the 6 main display LEDs for partial-illumination applications. In addition to the main bank of 6, the LM3535 is capable of driving an additional 2 independently controlled LEDs to support Indicator applications. The LED driver current sinks are split into three independently controlled groups. The primary group can be configured to drive up to six LEDs for use in the main phone display. Groups B and C are provided for driving secondary displays, keypads and indicator LEDs. All of the LED current sources can be independently turned on and off providing flexibility to address different application requirements. The LM3535 provides multi-zone ambient light sensing allowing autonomous backlight intensity control in the event of changing ambient light conditions. A PWM input is also provided to give the user the means to adjust the backlight intensity dynamically based upon the content of the display. The LM3535 provides excellent efficiency without the use of an inductor by operating the charge pump in a gain of 3/2 or in pass mode. The proper gain for maintaining current regulation is chosen, based on LED forward voltage, so that efficiency is maximized over the input voltage range. The LM3535 is available in a tiny 20-pin, 0.4-mm pitch, thin DSBGA package.