| 摘要 |
<P>PROBLEM TO BE SOLVED: To set a fixed and arbitrary clamp voltage without requiring an additional manufacturing process. <P>SOLUTION: When a voltage of a signal input line 6 is lower than a reference voltage VH, a signal Sc is set at an L level, a switch circuit 16 is turned off, and a switch circuit 17 is turned on, thereby turning off FETs 14, 15. When the voltage of the signal input line 6 exceeds the reference voltage VH, the signal Sc is set at an H level, the switch circuit 16 is turned on, and the switch circuit 17 is turned off, thereby making a clamp circuit 4 operable. When the input voltage is further increased and exceeds a clamp voltage VCL, a FET 13 is turned on so as to allow a current to flow into the FETs 13, 14 via a resistor 11, a terminal 1a, and a resistor 12 while the current is made to flow into the FET 15 in accordance with the current flow, thereby allowing the clamping operation. <P>COPYRIGHT: (C)2010,JPO&INPIT |
