| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor integrated circuit which can use a terminal as both a terminal subject to high voltage application and a terminal used to input a signal varying in a lower voltage range than that, without increasing the size of a circuit added.SOLUTION: An external input terminal 1 is designed as a common input terminal for a low voltage circuit section 2 and a high voltage circuit section 3. Between the external input terminal 1 and the signal input terminal of the low voltage circuit section 2 is connected an N-channel MOSFET 4, to the gate of which a potential equal to or higher than a maximum value 3 V for the input voltage of the low voltage circuit section 2 and lower than a maximum permissible input voltage VLset for the low voltage circuit section 2 plus a threshold voltage Vth of the N-channel MOSFET 4 is applied to keep the N-channel MOSFET 4 turned on. In this way, when a nonvolatile memory rewrite voltage of 9 V is applied to the external input terminal 1, the source potential of the N-channel MOSFET 4 is made to be equal to or less than the maximum permissible input voltage VLset for the low voltage circuit section 2. |
