A synchronous LED driver with dynamic level-shifting and simultaneous peak & valley current sensing for high-brightness lighting applications

This paper presents a synchronous hysteretic current controlled (SHCC) buck-type LED driver in order to achieve high power efficiency and high accuracy of the LED current simultaneously. A low-power dynamic level shifter is developed to enable the use of high-voltage power pMOS as the high-side power switch instead of traditional power diodes for significant conduction power loss reduction. The simultaneous peak and valley current sensing scheme is also created in the proposed driver to eliminate the use of any sensing resistor in the power stage for further power efficiency enhancement. Implemented in a high-voltage (HV) 0.35-µm CMOS, the proposed driver can deliver an average LED current of 1A. When the input voltage changes from 15V to 50V and the no. of series-connected LEDs varies from 1 to 12, the proposed driver can achieve the power efficiency of >89% and the average LED current error of <1.2%. The proposed SHCC LED driver achieves significant improvements in power efficiency and current accuracy over traditional peak- and hysteretic-current-controlled counterparts.