| 摘要 |
PURPOSE:To release the latch-up state without manual operation by providing a semiconductor switch circuit which disconnects an external power terminal and an internal power line by the output signal of a timer. CONSTITUTION:A microcomputer is constituted to have an external power terminal 2, a semiconductor switch circuit 3, a reset terminal 6 connected to a runaway detection timer (watchdog timer) 4 and a reset circuit 7, and an internal circuit 5. When the microcomputer 1 goes to the latch-up state, a program is not normally operated, and a watchdog timer output signal 41 is outputted to the semiconductor switch circuit 3, and this circuit 3 is turned off to turn off the power supplied from the external power terminal 2 to the internal circuit 5. Thus, it is unnecessary for a person to always confirm the latch-up state to turn off the power source, and the safety of the system is improved. |
