Power supply and reference voltage circuit for TFT LCD source driver

摘要

A liquid crystal power supply is provided which generates a high-precision drive power supply voltage supplied to a driver circuit by using a low-precision reference voltage generating circuit. The power supply circuit includes a DC/DC converter which generates a voltage having a size based on an oscillation signal from a power supply voltage and outputs the generated voltage as a drive power supply voltage; a stabilized power supply circuit which generates a highest-level reference potential for generating a gray-scale voltage in a driver circuit; a comparison unit which outputs a difference voltage according to a difference between the drive power supply voltage and the highest-level reference potential; an internal reference voltage generating unit; an error amplifying unit which amplifies a difference between the reference voltage and the difference voltage; and a PWM conversion unit which outputs an oscillation signal in response to the amplified difference.