一种基于开关电源的过流保护电路

文章设计一种基于谷值限流方式的过流保护电路, 利用整流开关管自身导通阻抗进行采样, 通过正负电压叠加的方式消除工艺偏差对限流阈值的影响。采用 $ 0.18 \mu m $ 的 BCD(bipolar-CMOS-DMOS)工艺进行设计, 电路结构简单、精确度高、响应速度快。在 Cadence 软件的 Spectre 环境下进行仿真验证, 该电路对电源电压和温度变化引起的过流阈值偏移有很强的抑制能力, 在 $ 3 \sim 6 V $ 的电源电压和 $ -55 \sim 125 ^{\circ}C $ 的温度范围内, 过流阈值的最大误差仅为 3.5%, 传输延时仅为 28 ns。

This paper designed an over-current protection circuit based on valley current limiting mode. The current was sensed by the on-resistance of the rectifier MOSFET. And the influence of process deviation on current limiting threshold was eliminated by superposition of positive and negative voltages. The design was carried out using 0.18 $ \mu $m bipolar-CMOS-DMOS(BCD) process. The circuit has the advantages of simple structure, high accuracy and fast response. The simulation was conducted in the Spectre environment of Cadence software, and the results show that the over-current threshold deviation caused by supply voltage and temperature changes is highly inhibited. The maximum error of the over-current threshold is only 3.5% in the range of 3-6 V supply voltage and -55-125 $ ^{\circ} $C. And the transmission delay is only 28 ns.