Power supply management circuit of vehicle-mounted RTC

The invention belongs to the technical field of automobile instruments, and particularly relates to a power supply management circuit of a vehicle-mounted RTC. The power supply management circuit of the vehicle-mounted RTC comprises a battery power supply circuit and a system power supply circuit, the system power supply circuit is connected with the battery power supply circuit in parallel, a parallel connection point is used for being connected with a power supply input end of the RTC, and a switching tube is further arranged on the battery power supply circuit in series and used for being switched on when voltage of a vehicle system power output end is smaller than a set voltage threshold value. And when the voltage at the output end of the vehicle system power supply is greater than a set voltage threshold value, the power supply switch is switched off, so that the vehicle system power supply supplies power to the vehicle-mounted RTC. Only when the vehicle system power supply does not output the voltage (