| 摘要 |
PURPOSE:To attain continuous sounding of a test signal by applying forcibly a clock signal to an input buffer circuit when it is detected that an output signal of an output buffer circuit is in the state of S channel. CONSTITUTION:An output buffer circuit 11 comprising 3rd-6th D-FF 7-10 is provided, which outputs an output signal of a decode circuit 6 decoding an output signal of an input buffer circuit 6 comprising 1st and 2nd D-FF 3, 4 in response to a 1st frequency divider output signal Q1 of a frequency divider circuit 2. Moreover, a selection circuit 14 is provided, which selects any of the 1st frequency divider output signal Q1 of the frequency divider circuit 2, its inverse of Q1 and a 2nd frequency divider output signal in response to an output signal of an AND gate 13 receiving a Q3 output of the 3rd D-FF 7 and an output control signal of a switch 12. Then a control signal driving a noise sequencer is obtained from an output terminal of the output buffer circuit 11. Thus, the test signal is continuously sounded. |
