Novel Current-limiting and Short-circuit Protection Technology for Low-side Power Switch

Abstract

Based on 0.35μm BCD process, a current-limiting and short-circuit protection circuit for low-side power switch is proposed. This design adopts the compact current comparator structure to achieve 2A current limiting protection and short circuit protection for the power switch over the temperature range of -25°C to 150°C, while quiescent power consumption is only 55.8μw. The sense-FET technology of this design can achieve 98.11% accurate current sampling. Simulation and experimental results show that when the load is lower than 7.5Ω at 18V supply voltage, the current-limiting protection is triggered to limit the output current to 2A. When the load is short-circuited, the short-circuit protection is triggered and the entire circuit will be shut down. The power supply rejection ratio of this design is -53dB, and the average temperature coefficient is 277ppm/℃, while only occupying an area of 0.055 mm2.