Patent ID: 6879132

Claim:
A switching power supply unit with a battery backup function by a secondary battery for obtaining a predetermined direct-current power supply voltage at the time of a stoppage in alternating current input, the unit comprising: a stabilized power supply circuit for smoothing alternating-current input from the commercial power supply and for converting the smoothed input to the predetermined direct-current power supply voltage which can continuously output the predetermined direct-current power supply voltage at normal operation time; and a power supply control circuit charged by the stabilized power supply circuit, including a direct-current power supply section for supplying power supply voltage to the stabilized power supply circuit at the time of a stoppage in the alternating-current input and a power supply control section for controlling the charging and discharging of the direct-current power supply section, and mounted in an enclosure in which the stabilized power supply circuit is mounted, wherein the direct-current power supply section includes a charging route and a discharging route separately.