| 摘要 |
PROBLEM TO BE SOLVED: To prevent a leakage current from flowing to the external input terminal side from an internal circuit.SOLUTION: An internal circuit 8 includes a differential amplifier circuit 11. The differential amplifier circuit 11 is constituted of an operational amplifier 9 including a negative feedback circuit 10. An external input terminal 2 is connected with the inverted input terminal of the operational amplifier 9. First and second electrostatic protective elements 5, 6 are connected in series between the external input terminal 2 and the ground. A reference voltage source 3 applies a bias voltage Vref to the joint P of the first and second electrostatic protective elements 5, 6, and the non-inverted input terminal of the operational amplifier 9. Since the bias voltage Vref is also applied to the external input terminal 2 connected with the non-inverted input terminal of the operational amplifier 9 by imaginary short circuit, both ends of the first electrostatic protective element 5 have the same potential. |
