Based On The New High Efficiency Charge Pump White Led Driver Chip Design

White LED is widely used as backlight source of LCD display in the portable equipments. To adapt to the power supply environment using single-cell Li battery and keep the same luminance from the uneven LED electric parameters, It's necessary to design special driver. By the forced of market demand and technology evolution, high efficiency, low noise and control flexibility have become the developing trend of the white LED driver in this years.A new LED driver based on charge pump is presented in this paper. This chip equips 1.5 times linear charge pump controlled by constant switching frequency to reach high efficiency, low ripple and low Electro Magnetic Interference (EMI); and it integrates a new-type LED driving structure to improve the control flexibility, by which the chip realizes enable control and 32-step circular proportional luminance dimming through a single pin.In the systemic design part, the principle of 1.5 times linear mode charge pump is analyzed in details at first, further more, including setting duty cycle and improving charge pump's efficiency. And then, a LED driving structure is designed to greatly enhance the program ability, features of relevant modules are figured out, including SCI definition, dimming ratio, program code table and DAC digit length; the ways to diminish the mismatch of LED luminance is discussed in this segment. Finally, the whole chip structure and its operation process are introduced.This paper mainly discusses the design of five sub-blocks, containing their functional principle, practical circuit and corner simulation results. There into, Oscillator outputs a square wave of 600KHz in frequency and 1/3 in duty cycle, Current Mode DAC changes the 8-bit digital inputs into driving current, Trimming Module provides a reference current with temperature compensation, Serial Control Interface realizes the enable control and program level detection and ROM Code Circuit finishes the exchange from program level to the DAC input code.After finishing circuit design, the author used process library to carry on simulation of whole chip function and key performance. The results indicated that the new LED driving chip has reached the design objective.