A high efficiency synchronous buck converter with adaptive dead time control for dynamic voltage scaling applications

An integrated synchronous buck converter with adaptive dead time controlled driver is presented in this paper. The integrated synchronous buck converter works in 2MHz PWM mode and the output voltage can be programmed by digital interface, which is suitable for powering the processor core and internal memory with dynamic voltage scaling (DVS) capability. The controller provides 0 and 100% duty cycles during DVS, maximizing tracking speed while saving power. The driver circuit detects body diode conduction by a proper biased N-type transistor. The synchronous N-type power MOS is turned on at the falling edge of body diode conduction detection in both DCM and CCM. The P-type power MOS is turned on at the falling edge of dead time detection in CCM. As a result, the dead time varies according to the load current, while the conduction time of the body diode in the synchronous power MOS is approaching to the delay of logic circuit and gate driver. The dead time control logic and gate driver are designed with low time lag to minimize body diode conduction time. Experimental results show that the converter can achieve fast reference tracking and the conversion efficiency is up to 90%.