High-Precision Over-Current Protection Circuit Design

To protect chips from damage caused by excessive current, this paper proposes a high-precision adjustable-threshold over-current protection circuit. The circuit employs a sampling transistor to proportionally sample the output current, ensuring accuracy in current limit values while reducing power loss. The over-current threshold is flexibly configured through a reference voltage circuit and an external resistor. To mitigate deviations caused by manufacturing processes and packaging, precise trimming techniques are integrated into the reference voltage circuit to enhance accuracy. Designed based on a $0.18 \mu \mathrm{~m}$ BCD process, simulation results demonstrate that the overall circuit achieves an over-current threshold accuracy within 3.3% under varying temperatures $\left(-40 \sim 125^{\circ} \mathrm{C}\right)$ and a 5 V power supply, with a configurable threshold range of 0.1 A to 2 A.