DRIVING POWER SUPPLY CIRCUIT WHICH GENERATES DRIVING POWER SUPPLY VOLTAGE OF DRIVER CIRCUIT USED IN DISPLAY DEVICE AND REFERENCE VOLTAGE USED IN THE DRIVER CIRCUIT TO GENERATE GRADATION VOLTAGE, DRIVER CIRCUIT VOLTAGE GENERATING METHOD TO GENERATE THE DRIVING POWER SUPPLY VOLTAGE AND THE REFERENCE VOLTAGE AND DISPLAY DEVICE HAVING THE DRIVING POWER SUPPLY CIRCUIT

摘要

PROBLEM TO BE SOLVED: To provide a liquid crystal driving power supply circuit in which a driving power supply voltage to be supplied to a driver circuit is precisely generated by employing a low precision reference voltage generating circuit. ;SOLUTION: A driving power supply circuit 11 consists of a DC/DC converter 34 which generates a voltage having a size based on oscillating signals VOUT from a power supply voltage V_cc of the circuit 11 and outputs the generated voltage as a driving power supply voltage V_dcdc, a stable power supply circuit 60 which generates a most significant reference potential V_refH used to generate a gradation voltage in a driver circuit, a comparison section 46 which computes the difference between the voltage V_dcdc and the potential V_refH and outputs the computed difference as a difference voltage, an internal reference voltage generating section 42 which generates an internal reference voltage VREF having a prescribed size, an error amplifying section 44 which computes the difference between a reference voltage that is determined by the generated voltage VREF and the difference voltage and a PWM converting section 32 which outputs the signals VOUT in accordance with the difference.;COPYRIGHT: (C)2003,JPO