In terms of requirements in portable application

this paper presents the design of high efficiency

high accuracy and low noise LED (Light Emitting Diode) driver circuit.1X/1.5X charge pump circuit is used to drive 4 LEDs.An improved LDO (Low Drop Out) current regulator circuit is designed to limited current error into 3% and achieves highest drive efficiency of 90.16% at the same time.Charge pump circuit design uses pseudorandom sequence generated by 8-bit LFSR (Linear Feedback Shift Register) .Switching noise is suppressed for 29.94dB.This design bases on IBM cmrf7sf 5V process

layout area is 1.51mm×1.14mm.It has been sent for tape out already.Simulation results prove the feasibility of this design.The LED driver designed is easy to be integrated with other modules in portable system and has a great value in practical application.