System of power management circuit

The invention belongs to the technical field of power management chips, and particularly relates to a device contained in a power management chip. The device comprises a switching circuit, a voltage detection circuit, a starting capacitor C1, a voltage maintaining circuit and a working circuit. One end of the switching circuit is connected with a power input end, and the other end of the switching circuit is connected with the starting capacitor C1. The input end of the voltage detection circuit is connected with the starting capacitor C1, and the output end of the voltage detection circuit is connected with the switching circuit. When the voltage of the starting capacitor C1 reaches the starting voltage of the power management chip, the voltage detection circuit detects that the voltage of the starting capacitor C1 reaches the starting voltage of the power management chip, then the voltage detection circuit enables the switching circuit to be disconnected, at the moment, an external power supply cannot conti