| 摘要 |
<p>PURPOSE:To obtain an optimum reset signal and to efficiently start the operation of a microcomputer, etc., by reset-resetting a certain time later since a sufficient operating voltage is obtained by starting constant-voltage operation. CONSTITUTION:When a source voltage VB rises sufficiently and a constant voltage output Vcc reaches a specific voltage at a point T2 of time, the constant voltage operation is started. Namely, the output voltage of a driving circuit 3 rises so as to make the bias of a transistor(TR) 1 shallow and becomes higher than the voltage of the constant output Vcc, so a TR 4 turns OFF and further a TR 5 turns OFF. The collector voltage of the TR 5, therefore, reaches Vcc, i.e., a level H and the output of a NAND gate 8 varies to a level L. Consequently, a TR 9 turns OFF to start charging a capacitor 10 through a resistance 11 and after a delay time determined by the time constant of the capacitor 10 and resistance 11 is elapsed, a reset signal *RES goes up to the level H at a point T3 of time, thereby resetting the resetting.</p> |
