| 摘要 |
PURPOSE:To obtain an IC device which can be tested readily in a short time by supplying the first signal to the initial stage of counter circuits connected in series with each other and supplying the second signal simultaneously to two counter circuits connected in not adjacent manner. CONSTITUTION:When a switch 11 is closed and an input signal is applied to a counter circuit 3, the counter circuits 4-6 of the rear stage count by the carry signals of the counter circuits 3-5 of the front stage to sequentially count as a timer and outputs minutes, hours and days to a display unit. At the testing time switches 12, 14 are closed by a control signal C1 to supply a test clock TC to the circuits 3, 5, thereby inspecting the existence or absence of the carry signal and the counting operation and the input stage to the next stage. Then, the signal C1 is stopped, and the circuits 4, 6 are similarly inspected by the signal C2. In this manner the operations of all the counter circuits can be confirmed at high speed readily only by the changeover of the control signal. |
