可防误翻转高精度欠压锁存电路设计

Design of high precision undervoltage lockout circuit with function of anti-error flip

在分析传统欠压锁存电路(UVLO:Under voltage lockout)工作原理的基础上,利用VIS 0.4μm BCD工艺设计一种具有防误翻转功能的高精度欠压锁存电路。该电路由3部分组成,以带隙比较器为核心,引入具有迟滞特性的防误翻转电路以保证欠压锁存信号能安全可靠地输出,并通过调整带隙基准的温度特性保证欠压锁存阈值精度,最后经过放大输出电路放大后,输出稳定的欠压锁存信号。采用Cadence软件对所设计的电路进行仿真。研究结果表明:在-40~125℃范围内欠压锁存阈值偏差最大为100 m V,阈值分辨率可达10-5 V,在3~5 V工作电压下,防误翻转电路开启阈值为2.95 V,能有效防止欠压锁存电路误翻转。该电路的设计理念和仿真结果有助于后期电源芯片的开发。

Based on the analysis of the traditional under voltage lockout theory, a high precision undervoltage lockout circuit with the function of preventing error flip was designed using the VIS 0.4 μm BCD process. The circuit was made up by three parts with the core of the bandgap comparator. The anti-error flip circuit with the hysteresis characteristics was designed to ensure that the UVLO circuit could output the safety signal. To guarantee the precise UVLO the temperature characteristic of the bandgap circuit was adjusted. At last, the output goes through the amplifier circuit to output the stable UVLO signal. The whole circuit was simulated in the Cadence software. The results show that the maximum threshold voltage distortion is only 100 m V and the threshold resolution ratio is 10-5 V at-40-125 ℃. Working in the voltage from 3 V to 5 V, the turn-on threshold of anti-error flip circuit is 2.95 V. It could keep the whole circuit in safe. The circuit design and simulation results can help power supply chip late development.