| 摘要 |
PROBLEM TO BE SOLVED: To decrease necessary external components as much as possible in case of application of a clamp circuit to signal input terminals of an IC. SOLUTION: A comparator 22 has an offset voltage of 0.1 V and compares a terminal voltage Vin1 with a clamp voltage VCL (5.1 V). When the terminal voltage Vin1 is equal to or lower than the clamp voltage VCL, the comparator 22 outputs H and a transistor Q11 is turned off. When a voltage exceeding the clamp voltage VCL is applied as the terminal voltage Vin1 , the comparator 22 outputs L and the transistor Q11 enters a sufficient ON state. At this time, a current flows through an external resistance R11, an input terminal 18, and the transistor Q11 to an output terminal of an operational amplifier 21. This current causes a voltage drop across the resistance R11 and the terminal voltage Vin1 drops down toward the output voltage Vc of the operational amplifier 21. |
