A 25W 97%-efficiency 3.5MHz integrated dimmable LED driver with lossless synchronous current control and floating NMOS-sensing scheme

This paper presents an integrated buck-type dimmable LED driver for high-brightness lighting applications. A lossless synchronous current control is developed to enable the driver to operate at high operation frequencies and achieve high current accuracy over a wide range of input voltages and output LED loads. The driver power efficiency is also benefited from realizing the synchronous rectification via a high-voltage (HV) dynamic-shifter-based gate driver and a HV floating NMOS sensing scheme. Implemented in a 0.5μm HV CMOS process, the proposed 45V LED driver can operate at 3.5MHz and achieve a peak power efficiency of 97.2% when driving 12 series-connected output LEDs (25W output power). The worst-case current error is within 2.8% of 700mA average LED current under different conditions. The proposed LED driver outperforms other state-of-the-art counterparts.