The TPS60251 is a high efficiency, constant frequency charge pump DC/DC converter that uses a dual mode 1x and 1.5x conversion to maximize efficiency over the input voltage range. It drives up to five white LEDs for a main display and up to two white LEDs for a sub display with regulated constant current for uniform intensity. By utilizing adaptive 1x/1.5x charge pump modes and very low-dropout current regulators, the TPS60251 achieves high efficiency over the full 1-cell lithium-battery input voltage range.