Low drain voltage S/H type PWM LED current driver for BLU in mobile LCD

A pulse-width-modulation light emission diode (LED) current driver for Back Light Unit in mobile liquid crystal display with minimum operable drain voltage of 360mV and 3σ current accuracy of 3% without trimming is proposed in 0.35μm BCD process. S/H type structure with sequential channel driving scheme reduces power consumption as reference current of current mirror with accurate output current. High reference current is just applied for the enhanced matching in sampling phase, while reference current is minimized in holding phase. The proposed triggered buffer amplifier enables fast and accurate PWM current driving.

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