一种DC/DC转换器的短路保护电路设计

针对负载短路会对DC/DC造成性能不稳定或损坏的情况,提出一种新型短路保护电路,有效地避免了传统电路在短路时大电流输出造成的能量浪费。该保护电路采用在负载短接时,通过改变电流限比较器输入端基准电压达到降低电路最大输出电流的措施。采用0.35 μm BCD工艺将该电路应用于一款高压同步BUCK型DC/DC转换器中,specter仿真结果表明,当负载短路时,该芯片的短路电流只有30 mA,与传统保护电路相比,降低了短路时的输出电流,达到节约能量的目的。

Design of a New Short Protection Circuit for DC/DC Converters

A novel short-circuit protection circuit is proposed with the case in consideration of the shorted load making performance of the DC/DC converter unstable or damaging the converter,effectively avoiding wasting energy of the converter when load is shorted and the output current is very large.The proposed circuit reduces the maximum output current for short circuit by changing the input reference voltage of the current limit comparator.The circuit is designed and applied in a synchronous BUCK DC/DC converter with high voltage based on 0.35 μm BCD process.The simulation results show that the short circuit current of the chip is 30 mA,decreasing output current and conserving energy compared with the traditional protection circuit.