One of recent problems of a display apparatus using a display panel is increase in a power consumption amount of a display panel driver that drives the display panel. One cause of the increase in the power consumption amount is increase in a size of the display panel. In the field of television, in particular, even in a case of a liquid crystal display panel, a television set exceeding 100 inches are in the market, and it is thought that this trend does not change in the future. As the size of the display panel increases, the capacitance of a data line increases, so that a power consumption amount of an output amplifier circuit that drives the data line increases. In addition, in the recent display apparatus, in order to decrease the number of drivers to be used, the number of outputs per one display panel driver tends to increase more and more, and therefore the power consumption amount of the display panel driver also increases more and more. For this reason, a temperature of the display panel driver in operation is increased.
One measure against the increase in the power consumption amount of the display panel driver is to supply an intermediate voltage between the power supply voltage VDD and a ground voltage VSS (=0 V) (typically, the intermediate voltage VDD/2 that is a half of a power supply voltage VDD), in addition to the power supply voltage VDD, and the intermediate power supply voltage is used to operate an output amplifier of the driver. For example, an amplifier that outputs an output voltage in the voltage range of VDD/2 to VDD is operated by use of the intermediate power supply voltage VDD/2 and the power supply voltage VDD, and an amplifier that operates in a voltage range of 0 to VDD/2 is operated by use of the intermediate power supply voltage VDD/2 and the ground voltage VSS. Thus, a power consumed in the amplifiers can be reduced. Such a technique is disclosed in, for example, Japanese Patent Publication (JP 2002-175052A).
However, the recent display panel driver is required to be operable in a low voltage to further reduce the power consumption amount. Currently, a driver for a liquid crystal display apparatus operates typically at 1.5 V; however, to suppress heat generation of the driver, the driver preferably operates at lower power supply voltage.
In addition, according to consideration by the inventor, it is advantageous in practice that the display panel driver is operable regardless of the presence or absence of supply of an intermediate power supply voltage. Of end manufacturers of display apparatuses, there are one who desires to reduce the power consumption amount by supplying the intermediate power supply voltage, and one who desires to simplify the configuration without supplying the intermediate power supply voltage. On the other hand, manufacturing respective types of display panel drivers with supply of the intermediate power supply voltage and with no supply of it causes increase in manufacturing cost. Cost reduction is preferable even for manufacturers of the display panel drivers and even for the end manufacturers of the display apparatuses.
However, a circuit described in the above Patent literature 1 cannot meet such requirements.