一种低功耗同步BUCK芯片的过零检测电路设计

Design of a zero- crossing detection circuit for low- power synchronous BUCK converter

同步BUCK芯片在轻载模式下会产生因电感电流倒灌而产生的额外功耗。针对这一问题,设计了一款过零检测电路。该电路采用两个不同电压门限采集技术,并对门限进行温度补偿,有效限制了电感电流的倒灌;同时设计了边沿隐匿电路,避免电路切换时引起的误触发。该过零检测电路基于0.25μm BCD工艺设计,利用HSPICE仿真验证。当系统温度在-40℃~120℃变化时,负阈值电压容差仅为0.2 m V,实现了高精度的过零检测,且静态功耗极低。

The synchronous BUCK converter will generate additional power loss caused by the reverse inductor current in the light load mode. A zero-crossing detection circuit was designed for this problem. By using two different thresholds acquisition technology, with the temperature compensation for the threshold,the current backward flowing is avoided;Edge occult circuit is also designed to avoid false triggering at svdtching moment.The zero-crossing detection circuit is designed based on 0.25μm BCD process,and car- fled on HSPICE.The simulation result shows that the negative threshold tolerance is only 0.2 mV when the system temperature vari- ous from -40℃to 120 ℃, and the static power consumeption is very low.