| 摘要 |
<p>PROBLEM TO BE SOLVED: To protect internal circuits from a reference voltage, if it applied by discharging a negative voltage inputted to a transistor when this voltage of specified value or less is inputted to a reference potential input terminal. SOLUTION: When a positive voltage higher than a power source Vdd is applied to each of input terminals Ii, its current is discharged to the power source through a forward diode Di1. When a negative voltage lower than a reference potential Vss is applied to each input terminals Ii, its current is discharged from a protective transistor Q through a reverse diode Di2. If an input/ output protective circuit is provided at an input or output terminal, internal circuits can be protected from an overvoltage inputted from these terminals. By floating the base of the transistor Q for discharging a negative overvoltage, it has no adverse effect on the normal operation of the internal circuit, this enhancing the reliability of an electronic apparatus.</p> |
