| 摘要 |
<p>PURPOSE:To apply the operating voltage to two power supply terminals in the satisfactory timing by controlling a transistor put into a line which supplies the power to one of both terminals in accordance with the voltage supplied to the other terminal. CONSTITUTION:At application of a power supply, the constant voltage is applied to a main power supply terminal 20 of a microcomputer 19 from a constant voltage circuit 6 via a 1st line 24. If the voltage level of the circuit 6 rises up under such conditions, a detecting transistor TR13 and a 2nd TR29 are turned on and the prescribed voltage is applied to the base of a 1st TR28. Thus the TR28 is turned on and the constant voltage is applied to a sub-power supply terminal 21 from the circuit 6 via a 2nd line 27 later than the terminal 20. When the power supply is cut off, the operating voltage is not applied quickly to the terminal 21. In this case, however, the constant voltage is applied to the terminal 20 from a back-up capacitor 26. As a result, the storage contents of a RAM of a computer 19 are held as they are.</p> |
