| 摘要 |
PURPOSE:To prevent occurrence of a malfunction as prior art by selectively setting whether a reference potential is dropped or not at the stage of an assembly. CONSTITUTION:When a switching pad 5 is not connected to an external power source pin 2 or not grounded, an external power source potential Vex of the pin 2 is dropped by a controller 3, and an internal power source potential Vin equal to a reference potential Vref is output from an internal power source 4, whereas when the pad 5 is connected to the pin 2 or grounded, the potential Vin equal to the potential Vex is output by power source supply means of the controller 3. Accordingly, whether the potential Vex is dropped or not can be selectively set at the stage of an assembly, and occurrence of a malfunction like when the internal power source potential is selectively switched under the control of an external clock signal like prior art can be prevented. |
