The embodiment of the application provides a BUCK circuit lower tube
driving circuit power supply, a BUCK circuit, and a
switching power supply
chip, the power supply comprises an error
current generation module, an error current
processing module, and a power supply output module, the error current
processing module comprises an error
voltage generation circuit, a transient load response
capacitor, and a first
CASCODE current mirror circuit, the error
voltage generation circuit receives error current generated by the error
current generation module to output error
voltage, one end of the transient load response
capacitor is connected with an output end of the error current
processing module, the other end is connected with a gate of a
common source end of the first
CASCODE current mirror circuit, and the output end of the error voltage generation circuit serves as the output end of the error current processing module. The transient load response is good, the rising edge time of the power MOS tube is very short, the switching speed is fast, the cross-over loss is reduced, on the other hand, an external large-capacity
capacitor is not needed, PIN pins are saved, and material cost is reduced.