| 摘要 |
<p>PURPOSE:To provide a backup circuit for the semiconductor memory which securely backs up the semiconductor memory even when the semiconductor memory is used while its power supply time is short or the power-supply frequency is low. CONSTITUTION:The power source is connected to the anode of a diode 3, whose cathode is connected to a supercapacitor 7 through a protection resistor 6. The cathode is further connected to one input of a power source switch 2. A backup primary battery 56 is connected to the other input of the power source switch 2. When the voltage of the power source input is high, the cathode-side input of the diode 3 becomes the output of the power source switch 2, but when the voltage is low, the primary battery 5 becomes the output of the power source switch 2. The output of the power source switch 2 is connected to the semiconductor memory. If the power source input voltage drops, the diode 3 disconnects the power source input and supercapacitor 7 from each other first and the source voltage is held by the capacity accumulated in the supercapacitor 7.</p> |
