| 摘要 |
PURPOSE:To reduce the number of external terminals thereby to simplify the integrated circuit for a watch by using the time and calender information display interchanging external terminal as a testing one. CONSTITUTION:When a push button is depressed, the output of an FF 13 is reversed through the external terminal 9 of an integrated circuit 1, a chattering preventing device 10 and a multivibrator 11 so that the time display by the hour, minute and second counters 6a to 6c is converted into the calendar display by day and month counters 6d and 6e by the actions of a display interchanging circuit 7 and a display driving circuit 8. That terminal 9 is supplied with the high frequency signals for energizing the counters 6a to 6e, and the combinations of the test signals at high and low levels to be fed to external terminals 21 and 22 are varied. An AND gate 17, unit up-shift preventing OR gates 4a to 4d, and control circuits 5a to 5e are controlled through the respective FFs 20a, 20b and so on of a shift register 20 so that the propriety tests of the counter and logic circuits are accomplished by the use of the display interchanging external terminals through the measurements of the output voltages of the external terminals 8-1 and so on. As a result, the number of the external terminals is reduced, and the logic circuit is simplified. |
