| 摘要 |
PURPOSE: A liquid crystal display driver having a segment and a combination input and output ports is provided to use the liquid crystal display driver without a power voltage limit or an extra port by installing the segment and the combination input and output ports regardless of an electric potential difference within an integrated circuit. CONSTITUTION: A liquid crystal display driver sets a value so that a VDD dose not exceed a VEE and applies always a VEE which is the highest potential to a well bias of a combination terminal. The liquid crystal display driver inserts PMOS transistors(QN18,QN19,QN20) selected according to a segment and a mode of a combination input and output port(such as a segment mode, input mode, input mode). The liquid crystal display driver applies the VDD or VEE through a level shift circuit LS10,LS11,LS13,LS14 to a gate mode and determines on or off. A well bias(N-type) of the port prevents a current from passing caused by a parastic diode by applying always high potential through a bias circuit(10) regardless of the VDD, VEE potential. The VDD and VEE are respectively connected to a source of two PMOS transistors(QN16,QN17) and a cathode of two diodes(D11,D12) of the bias circuit(10) and applies different opposite potential each other to the gate of two PMOS transistors(QN16,QN17).
|
