| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To detect the inner temperature of a CPU at low costs without making the CPU a proprietary component. <P>SOLUTION: The I/O port of a CPU alternately repeats 'output port set' having the resistor component of transistors 121 and 122 and 'input port set with pull-up' having a transistor 111 as a pull-up resistor while holding 'input port set with no pull-up' between them. A counter 220 counting a clock CLK is reset at each edge of an output pulse from a comparator 203 for comparing the potential at a port terminal 114 with a reference voltage VTH1. When the ON resistance of the transistor 111 is varied to cause variation of the comparator input and the count of the counter 220 reaches an abnormality decision value under a state where no pulse is delivered, output of a latch circuit 221 goes H and an alarm section connected thereto informs temperature abnormality to the CPU. <P>COPYRIGHT: (C)2003,JPO</p> |
