| 摘要 |
PURPOSE:To obtain the device which is tolerant to fluctuations of the ground level (GND level) that the device itself causes by providing an input buffer which temporarily receives an external digital signal prescribing display operation and a capacitor for the ground which is arranged on the output side of the buffer. CONSTITUTION:While the upper transistor(TR) in the final stage in the input buffer is ON, the potential difference from Vcc is constant, but the potential difference from the GND level is not constant if the GND level varies. The capacitor C2 is added to raise the output of the input buffer 2 to the plus side when the GND level fluctutates to the plus side, thereby suppressing missensing operation. When the output state is a high level and the GND level fluctuates to the minus side, the output is pulled to the minus side, but the pulling potential difference is equal to or less than the potential difference at the time of the fluctuations of the GND level, so there is no problem. Namely, the missensing when the GND level fluctuates to the minus side can be prevented by the addition of the capacitor C2.
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