A Single-Stage Solar-Powered LED Display Driver Using Power Channel Time Multiplexing Technique

A unified single-stage solar harvester/LED display driver with power channel time multiplexing technique is proposed to achieve simultaneous maximum power point tracking (MPPT) and LED current regulation using two control variables. The operation state is automatically selected between power redundant and power hungry states to implement adaptive power steering. The D-hopping technique is proposed to ensure fast LED current recovery during PWM dimming and uninterruptible MPPT and LED powering. This design is fabricated with 0.25-μm CMOS process. The LED current is regulated between 20 and 50 mA with 500-kHz switching frequency. An 85-ns PWM dimming recovery time is achieved. No observable fluctuations are found during the PWM dimming and solar energy available/unavailable transitions.