Abstract: A protection switch circuit includes: an input terminal configured to receive a DC input voltage; an output terminal; a switch provided between the input terminal and the output terminal; a determination circuit configured to compare the input voltage with N threshold voltages (N is a natural number); and a gate controller configured to control the switch based on a comparison result of the determination circuit, wherein the determination circuit includes: an OTPROM (One Time Programmable Read Only Memory) to which N pieces of setting data indicative of each of the N threshold voltages are written under software control, and a comparison circuit configured to compare the input voltage with each of the N threshold voltages according to the N pieces of the setting data written to the OTPROM.

Abstract: A protection switch circuit includes: an input terminal configured to receive a DC input voltage; an output terminal; a switch provided between the input terminal and the output terminal; a determination circuit configured to compare the input voltage with N threshold voltages (N is a natural number); and a gate controller configured to control the switch based on a comparison result of the determination circuit, wherein the determination circuit includes: an OTPROM (One Time Programmable Read Only Memory) to which N pieces of setting data indicative of each of the N threshold voltages are written under software control, and a comparison circuit configured to compare the input voltage with each of the N threshold voltages according to the N pieces of the setting data written to the OTPROM.

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 laser element driving apparatus includes a laser element that varies the light intensity corresponding to the current that flows thereto; a photodetection element that monitors and converts the light intensity of the laser element to electric signals; an emission control switch that controls the current that flows to the laser element; a feedback amplifier that controls the emission control switch by feeding back electric signals from the photodetection element; and an emission control switch controlling circuit that turns the emission control switch OFF when determining as abnormal a current flowing continuously to the laser element for a predetermined time from the beginning of the laser element light emission and/or that controls the emission control switch such that the current flowing to the laser element at the time of beginning of the laser element light emission is gradually increased. The laser element driving apparatus safely drives a laser element.

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.