| 摘要 |
PROBLEM TO BE SOLVED: To prevent waveform ringing in a wavefrom output and to avoid a problem in wavefrom transmission by turning off one or more output buffer circuits when the temperature is a prescribed temperature or higher. SOLUTION: When the value of current flowing in a temperature detection diode 7 is Ia at a normal temperature, the potential of a cathode becomes Rc×Ia (Rc is the resistance value of a resistor element 8). When the potential Vref of reference potential 6 is larger than Rc×Ia, a potential comparison circuit 5 outputs logic 1. A first output buffer circuit 1 inputting the output of an electronic comparison circuit 4 to an output control signal input terminal as an output control signal is turned on. It becomes Vref<Rc×Ib at the temperature of not less than a temperature Tb at which it becomes Vref=Rc×Ib. The output of the potential comparison circuit 5 outputs logic 0, a buffer circuit 1 is turned off and a bus is driven from a waveform output terminal 4 only by a second buffer circuit 2. The first output buffer circuit 1 is turned off at the temperature of not less than the temperature Tb. The current driving ability of the output buffer circuit driving the waveform output terminal 4 is reduced. |
