| 摘要 |
PURPOSE:To miniaturize the power supply unit and to extend backup time by impressing a DC power supply through a diode for preventing back flow to input terminals of the DC power supply of plural stabilized power supply units and connecting a capacitor for backup. CONSTITUTION:An input power supply Vi applied by connecting a battery BT to a power supply input terminal 2 of a system regulator 1 is applied to the power supply voltage input terminals of stabilized power supply units 3, 4 and 5. On the other hand, the input power supply Vi is applied through a diode 21 for preventing back flow to a backup input terminal 20, and a capacitor 22 for power supply backup is connected between the backup input terminal 20 and the ground. Then, a reference voltage Vr of a reference voltage generator 7 is applied to the reference voltage input terminal of a stabilized power supply unit 6 and applied through a buffer circuit 23 to the reference voltage input terminals of the stabilized power supply units 3, 4 and 5 as a reference voltage Vra. Thus, the capacity of the capacitor 22 for power supply backup can be reduced, and the power supply unit can be miniaturized. |
