Design of high-performance integrated dimmable LED driver for high-brightness solid-state lighting applications

This paper presents a high-voltage buck-type dimmable LED driver for high-brightness solid-state lighting applications. A synchronous hysteretic current control (SHCC) scheme is developed to regulate the LED current with high accuracy under different input voltages and various numbers of output LEDs. With a low-power high-speed dynamic level shifter, the proposed HV gate driver achieves short propagation delays and enables high-frequency operation of the high-voltage SHCC LED driver with an on-chip high-side power pFET. Both peak and valley current sensors are also proposed for high-speed LED current monitoring. Without any power diode and sensing resistor in the power stage, the power efficiency of the proposed LED driver can be enhanced significantly. Implemented in a 0.35-µm HV-CMOS process, the proposed driver can take a high input voltage up to 50 V and deliver an average LED current of 1 A for 12 series-connected output LEDs with a maximum output power of about 46 W. When the input voltage changes from 15 to 50 V and the number of series-connected LEDs varies from 1 to 12, the proposed driver achieves peak power efficiency of 98.8 % and the average LED current error of <1.2 %. The proposed LED driver supports high operation frequency of up to 2.2 MHz and high PWM dimming frequency of 20 kHz with a wide duty ratio from 10 to 100 %. The proposed SHCC LED driver achieves significant improvements in power efficiency and current accuracy over state-of-the-art counterparts.