BUCK变换器中过零检测电路的设计
Design of zero-crossing detection circuit in BUCK converter

针对同步BUCK变换器轻载下会发生电流倒灌从而降低芯片效率这一问题，设计了一款基于CSMC 0.35 μm CMOS工艺的低功耗过零检测电路。该电路不使用运算放大器实现了电流比较的功能，同时增加抗振铃电路，得到稳定的电感电流。此过零检测电路已成功应用于一款基于COT控制模式的BUCK变换器芯片，经流片测试，电感电流在9 mA时同步整流管关断，且电路静态功耗仅为1 μA。
The synchronous BUCK converter under light load will occur on the current irrigation.To solve this problem for reducing the chip efficiency,a low power zero crossing detection circuit is fabricated by using CSMC 0.35 μm CMOS process.The circuit does not use the operational amplifier to achieve the current comparison function,while increasing the anti ringing circuit,thus a stable inductor current can be obtained.The zero crossing detection circuit has been successfully applied to a BUCK converter chip based on COT control mode.When the inductor current is 9 mA,the synchronous rectifier is turned off and the static power consumption of the circuit is only 1 μA