Abstract: A novel green mode switch mode power supply (SMPS) buck regulator with an on-chip power switch is proposed.By adopting PWM/Burst multi-mode operation,its conversion efficiency is enhanced over the entire load range.It reduces the light-load and standby power dissipation of modern portable products powered by batteries,which results in prolonging their standby time and battery lifetime.Moreover,a seamless transition is successfully realized by over voltage suppression.In addition,an on-chip current sensing technique with high precision and efficiency has been introduced into the control strategy to improve its efficiency further.The regulator is designed and fabricated in 1.5μm BCD (Bipolar-CMOS-DMOS) technology.The test results show that all expected performances are achieved.

Key words: PWM mode, Burst mode, seamless transition, synchronous rectify, on-chip current sensing