Abstract: A piezoelectric transducer drive circuit comprising a variable current source being controlled by a differential operational amplifier, a constant current source and a switch means connected in series with the variable current source between a power supply voltage VDD and the ground potential, and a capacitor having opposite ends connected with the output of the variable current source and one input terminal of the differential operational amplifier, wherein the switch means takes nonconducting state upon stoppage of applying operation of intermittent operation and takes conducting state at the time of applying operation, and an error reference voltage VREF1 takes a first value upon stoppage of intermittent operation and transits gradually to a second value as the operation is started. Overshoot current of a cold cathode ray tube can be deterred when applying operation of intermittent operation is started.

Abstract: A piezoelectric transducer drive circuit comprising a variable current source being controlled by a differential operational amplifier, a constant current source and a switch means connected in series with the variable current source between a power supply voltage VDD and the ground potential, and a capacitor having opposite ends connected with the output of the variable current source and one input terminal of the differential operational amplifier, wherein the switch means takes nonconducting state upon stoppage of applying operation of intermittent operation and takes conducting state at the time of applying operation, and an error reference voltage VREF1 takes a first value upon stoppage of intermittent operation and transits gradually to a second value as the operation is started. Overshoot current of a cold cathode ray tube can be deterred when applying operation of intermittent operation is started.

Abstract: A power supply capable of making soft start efficiently. A power supply (10) is such that the time lag from the soft start trigger representing the start of soft start control to the actual soft start can be decreased by offsetting the potential of a soft start signal from the ground potential. The offset is slightly lower than the minimum potential of a triangular signal. The highest potential level of the soft start signal is preferably lower than the power supply potential.