| 摘要 |
PURPOSE:To reduce the non-initial set time and to attain sure initial setting, by applying an output of an oscillating circuit to a mode set terminal of an integrated circuit by a prescribed time only via a time and level set circuit from the power-on of the integrated circuit. CONSTITUTION:The time/level set circuit comprising an oscillating circuit 41, a tri-state buffer circuit 42, a time constant circuit 43, and a pull-up resistor 44 is provided between an IC power supply Vcc and a mode set terminal 40 of an IC circuit 10. When the power supply Vcc is applied, the circuits 41, 43 are started and after a pulse signal is applied to the terminal 40 for a prescribed time, the terminal 40 is fixed to a level of logical 1 with the resistor 44. The waveform of an input signal to the terminal 40 is shaped at a Schmitt trigger buffer 32, and its output is applied to an in-phase delay circuit 33 delaying it for a prescribed time, an exclusive OR circuit 34 and a mode switching circuit. A power-on reset pulse is generated from the circuit 34 at each pulse and the IC10 is set initially with the pulse. |
