| 摘要 |
<p>PURPOSE:To prevent malfunction of an oscillating device due to the unstable oscillation at the early period of oscillation, by enabling the selection between a means which supplies clock signals when the prescribed time elapses and a means which can freely change the time by which the supply of clocks is started. CONSTITUTION:The first means, by which the output ST5 of a fall detecting circuit 5 is turned into the clock supply start signal CLST of a clock supply control circuit 8 in accordance with the output of an FF10 of a clock supply start signal selecting circuit 6, receives an output of the oscillation start signal OST from a rise detecting circuit 4 in case the potential of an external input terminal 3 has a rise and then supplies clocks to a microprocessor 11. While the second means through which the circuit 6 selects the signal CLST with the output of a counter 9 starts the supply of clocks in a certain period after the rise of potential of the terminal 3 regardless of the fall of the potential of the terminal 3. The first and second means are easily executed with an instruction program of the processor 11.</p> |
