High-effciency Charge Pump LED Driver Circuit Design

With the wide range of LED applications, the supply of electricity is required tomeet a higher demand. The high efficiency and low-cost power supply system attractmore and more attention. Charge pump exhibits the advantages of lowelectromagnetic interference (EMI), the small area occupied, low power consumptionin the closed or no load state and relatively simple and inexpensive design. Thus,charge pump has been widely used in a variety of LED driver circuit. Therefore,research on high-effciency driver circuit is of particular importance.The high-low static power conversion efficiency charge pump LED driver circuithas been designed. Constant output voltage of5V can provide up to150mA of loadcurrent, meeting the six-way parallel LED driver application requirements. Operatingfrequency of1MHz and only41~10μF external capacitance significantly reduceEMI radiated interference and application costs. The main driver circuit usinghigh-efficiency adaptive circuits for different input voltage, the boost mode in1x/1.5x/2x automatically switch to achieve in a wide2.7~5.5V input voltage rangeof high conversion efficiency. Skip mode circuit, significantly reducing the outputpower control due to the continuous switch caused by the switching losses. The coremodule of the circuit includes the bias circuit，the charge pump mode control circuit,the bandgap reference circuit, oscillator and clock control circuit, error amplifiercircuit, overvoltage protection circuit and so on. UsingCSMC0.5μm CMOS processto design each sub-module, including architecture selection, and size of each MOStube set. The circuit simulation, and adjustment and validation of parameters havebeen carried out by Cadence simulation tools spectre. The functionality andperformance of various sub-modules meet the design requirements and quiescentcurrent level is controled on μA. The overall circuit simulation shows that when theload is0~150mA and input voltage is2.7~5.5V, the circuit can output a constant voltage of5V. Shutdown current is less than1μA. When the input voltage is equalto3.6V, the static power consumption is only0.3mW. Therefore, the drive circuit isdemanding for the quiescent current battery-powered system providing a solution.