Abstract: A MEMS microphone includes a diaphragm having conductivity, first and second variable capacitors respectively including first and second fixed electrodes, a first voltage output section that outputs a first voltage changed according to a change in a capacitance of the first variable capacitor, and a second voltage output section that outputs a second voltage changed according to a change in a capacitance of the second variable capacitor. The first and second fixed electrodes face the diaphragm. The capacitances of the first and second variable capacitors are changed in accordance with a vibration of the diaphragm. A first bias voltage is applied to the first fixed electrode. A reference voltage is applied to the second fixed electrode. A second bias voltage is applied to the diaphragm. A difference between the second bias voltage and the reference voltage is half of a difference between the first bias voltage and the reference voltage.

Abstract: A light receiving detection circuit has a light receiving element configured to receive light emitted from a corresponding projection element, a current/voltage conversion circuit that converts a current signal passing through the light receiving element into a voltage signal, and a filter portion that has a plurality of stages. The filter portion has a high-pass filter and an amplifying circuit. The high-pass filter is able to be switched such that a time constant of the high-pass filter increases when the light receiving element receives light emitted by the corresponding projection element such that the time constant decreases when other projection elements except for the corresponding projection element emit the light.

Abstract: A light receiving detection circuit has a light receiving element configured to receive light emitted from a corresponding projection element, a current/voltage conversion circuit that converts a current signal passing through the light receiving element into a voltage signal, and a filter portion that has a plurality of stages. The filter portion has a high-pass filter and an amplifying circuit. The high-pass filter is able to be switched such that a time constant of the high-pass filter increases when the light receiving element receives light emitted by the corresponding projection element such that the time constant decreases when other projection elements except for the corresponding projection element emit the light.

Abstract: A parallel monitor circuit having a simple circuit configuration, in which a voltage divider circuit can be formed with resistors having the same resistance value, includes plural capacitors are connected in series, and a bypass device of each of parallel monitor circuits is connected in parallel with each capacitor. Plural voltages Va different from one another by a constant voltage are sequentially outputted from a digital-to-analog converter, and the voltages Va are inputted to plural parallel monitor circuits. When a charging voltage is higher than a monitor voltage determined by the voltage Va, each capacitor discharges through the bypass device, and the capacitor is kept at a predetermined monitor voltage.

Abstract: A current limiter circuit in an IC having a power transistor and an output current detection circuit connected in series with the power transistor. A comparator, a first reference voltage generator circuit and a second reference voltage generator circuit are also included in the current limiter circuit. The comparator generates a control signal for stopping a drive of the power transistor for a predetermined time. The comparator generates the control signal according to a detection signal obtained by the output current detection circuit and a second reference voltage obtained by the second reference voltage generator circuit when the output current of the power transistor reaches a predetermined value larger than the predetermined limit value. The first reference voltage generator circuit is provided externally of the IC and the second reference voltage generator circuit is included within the IC.

Abstract: An over-current protection circuit of a semiconductor circuit including a power transistor for outputting current output, a first output current detection circuit and a current limiter circuit for limiting the output current by stopping the output current of the power transistor for a predetermined period in response to a first detection signal from the output current detection circuit when the output current of the power transistor reaches a predetermined limit value. The over-current protection circuit has an output current detection transistor current-mirror connected to the power transistor and a second output current detection circuit for generating a second detection signal according to an output current of the output current detection transistor when the output current reaches the predetermined limit value. Further, the output current of the power transistor is cut off for the predetermined period by operating the current limiter circuit in response to the second detection signal.

Abstract: A parallel monitor circuit having a simple circuit configuration, in which a voltage divider circuit can be formed with resistors having the same resistance value, includes plural capacitors are connected in series, and a bypass device of each of parallel monitor circuits is connected in parallel with each capacitor. Plural voltages Va different from one another by a constant voltage are sequentially outputted from a digital-to-analog converter, and the voltages Va are inputted to plural parallel monitor circuits. When a charging voltage is higher than a monitor voltage determined by the voltage Va, each capacitor discharges through the bypass device, and the capacitor is kept at a predetermined monitor voltage.

Abstract: A back electromotive force detection circuit 12 incorporates an A/D conversion circuit 14 that converts the output from a differential amplifier circuit A2 into a digital signal and an offset calculation circuit 15 that sets the resistance value of a variable resistor R2 according to the output from the A/D conversion circuit 14. Based on the difference between the output from the A/D conversion circuit 14 as obtained when the drive current fed to a motor coil L equals zero and the output from the A/D conversion circuit 14 as obtained when the drive current fed to a motor coil L equals a predetermined value, the offset calculation circuit 15 sets the resistance value of the variable resistor R2.

Abstract: A back electromotive force detection circuit 12 incorporates an A/D conversion circuit 14 that converts the output from a differential amplifier circuit A2 into a digital signal and an offset calculation circuit 15 that sets the resistance value of a variable resistor R2 according to the output from the AID conversion circuit 14. Based on the difference between the output from the AID conversion circuit 14 as obtained when the drive current fed to a motor coil L equals zero and the output from the A/D conversion circuit 14 as obtained when the drive current fed to a motor coil L equals a predetermined value, the offset calculation circuit 15 sets the resistance value of the variable resistor R2.

Abstract: When the drive current fed to a VCM 3 is large, a driver D2 is turned on, and a driver D3 is turned off so that the current detected by a current detection amplifier A1 is fed back based on the voltage across a detection resistor RS1. When the drive current fed to the VCM 3 is small, the driver D2 is turned off, and the driver D3 is turned on so that the current detected by a current detection amplifier A2 is fed back based on the voltage across a detection resistor RS2.