The CAT3604 is a charge pump operating in either 1x (LDO) mode or 1.5x fractional mode regulating current through each of the 4 LED pins. Operation at a fixed high frequency of 1MHz typical allows the use of very small value ceramic capacitors. The CAT3604 drives white light-emitting diodes (LEDs) connected in parallel and provides tightly matched regulated current to achieve uniformity of brightness in LCD backlighting applications. An external resistor RSET controls the output current level. LED currents of up to 30mA are supported over a range of input supply voltages from 3V to 5.5V, making the device ideal for battery-powered applications.