| 摘要 |
A liquid crystal driving integrated circuit capable of adjusting display contrast and requiring no externally attached components. Transmission gates TG<HIL><PDAT>0</BOLD><PDAT>-TG<HIL><PDAT>10 </BOLD><PDAT>are provided at respective connection points of twelve resistor elements connected in series between a power supply and the ground. One of the voltages V<HIL><PDAT>0</BOLD><PDAT>-V<HIL><PDAT>10 </BOLD><PDAT>derived from the transmission gates TG<HIL><PDAT>0</BOLD><PDAT>-TG<HIL><PDAT>10 </BOLD><PDAT>in accordance with control signals CA<HIL><PDAT>0</BOLD><PDAT>-CA<HIL><PDAT>10 </BOLD><PDAT>is applied to an operational amplifier <HIL><PDAT>8, </BOLD><PDAT>and used as a reference voltage VLCD<HIL><PDAT>0</BOLD><PDAT>. The control signals CA<HIL><PDAT>0</BOLD><PDAT>-CA<HIL><PDAT>10 </BOLD><PDAT>are obtained by decoding control data D<HIL><PDAT>0</BOLD><PDAT>-D<HIL><PDAT>3 </BOLD><PDAT>supplied from an external source by a decoder <HIL><PDAT>19. </BOLD><PDAT>Therefore, the reference voltage VLCD<HIL><PDAT>0 </BOLD><PDAT>can be set in a plurality of stages simply by changing control data D<HIL><PDAT>0</BOLD><PDAT>-D<HIL><PDAT>3 </BOLD><PDAT>to a user specified value. As the twelve resistor elements connected in series are formed on the same semiconductor substrate, display contrast can be adjusted without requiring any external components attached to a liquid crystal driving integrated circuit <HIL><PDAT>1. </BOLD></PTEXT>
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