Abstract: A test signal is supplied to a test switch provided between a D/A converter for selecting and outputting a gray scale voltage of the driving circuit and an amplifier for amplifying and supplying an output voltage at the D/A converter to set a test mode, and an output voltage of the D/A converter is directly measured by a measuring device through the test switch to measure an ON resistance of a gray scale voltage selection circuit of the D/A converter.

Abstract: An output circuit of a data driver in a liquid crystal display apparatus conducts a dot inversion driving method. The output circuit includes amplifiers that output the data signals on data lines, switches that separate the data lines from the amplifiers and short/precharge circuit that shorts the lines between the data lines, for a predetermined time, and then supply the same polarity precharge voltage as the polarity when writing the data signals on the data lines in a next sequence.

Abstract: A test signal is supplied to a test switch provided between a D/A converter for selecting and outputting a gray scale voltage of the driving circuit and an amplifier for amplifying and supplying an output voltage at the D/A converter to set a test mode, and an output voltage of the D/A converter is directly measured by a measuring device through the test switch to measure an ON resistance of a gray scale voltage selection circuit of the D/A converter.

Abstract: A power-on reset circuit has first and second reference potential circuits and a comparator. The first and second reference potential circuits are such that their output voltage curves with respect to the power supply voltages intersect at a predetermined power supply voltage. The comparator compares output voltages of the first and second reference potential circuits. The first reference potential circuit has a first and a second resistor connected in series and a first non-linear resistor element circuit all connected between a first and a second power supply terminal. A node between the first and second resistors forms an output terminal of the first reference potential circuit. The second reference potential circuit has a third, fourth and fifth resistors connected in series between the first and second power supply terminals and a second non-linear resistor element circuit connected in parallel to the fourth resistor.

Abstract: First and second MOS transistors are connected through a first resistance to each other in series between first and second potentials. Third and fourth MOS transistors are connected in series between the first and second potentials. Gates of the first and third MOS transistors are commonly connected to each other, and connected to a drain of the third MOS transistor. A diode, a Zener diode, and a second resistance are connected in series between the first and second potentials, such that cathodes of the diode and the Zener diode are connected to each other. A constant voltage generated at a connecting point between the second resistance and the serial connection of the diode and the Zener diode is applied to a gate of the fourth MOS transistor. A constant current circuit thus obtained operates with a low voltage and is adapted to be connected even to a comparator having a large dependency on the threshold voltages.