Abstract: A circuit comprises an inductor, a load, and a controllable switching device arranged in either a first configuration: switchable between the load being bypassed and the inductor energised, and current flowing through the load, and the inductor discharging energy into the load; or, a second configuration: switchable between current being permitted to flow through the load, inductor and controllable switching device in series, energising the inductor, and the current flowing through the load, and the inductor discharging energy into the load. The circuit further comprises control means for controlling the switching device, a load current sensing resistor connected in series with the load, and a demand signal input. Monitoring means is arranged to monitor the demand signal and the voltages across the sense resistors, and generate a monitor signal. The control means is arranged to receive the monitor signal and to switch the switching device in response the monitor signal exceeding a predetermined threshold.

Abstract: A power supply circuit has a first MOSFET having a body region between the source and drain. The body region is connected so as to be at the same potential as the source. Application of a suitable potential to the gate causes the MOSFET to switch to a conductive on state. The power supply circuit also has signal generation circuitry, which generates a signal indicative of a conductive state of the first MOSFET. The signal generation circuitry generates a reference voltage of a predetermined potential difference from the source potential. The power supply circuit further comprises a second MOSFET having a body region connected so as to be at the same potential as the drain of the first MOSFET, and the second gate is connected to receive the reference voltage.

Abstract: A method of controlling a brushless DC motor of the type having a stator, comprising a stator winding excitable to generate a stator magnetic field, and a rotor, arranged to rotate with respect to the stator and comprising permanently magnetized material arranged to generate a rotor magnetic field to interact with the stator magnetic field to produce rotation of the rotor. The method comprises the steps of driving current through the stator winding to generate a stator magnetic field to interact with the rotor magnetic field, detecting rotor position with respect to the stator, and cyclically commutating the stator winding current according to rotor position as the rotor rotates. Each commutation cycle includes a drive portion during which current is driven through the stator winding in one sense and at the end of which the driving of current in said sense is ceased.

Abstract: An amplifier (1) adapted to receive an input signal and to generate an output signal at an amplifier output (7) according to the input signal, the amplifier (1) comprising: a feedback circuit arranged to provide a feedback signal indicative of the output signal; an error signal generating circuit (12, 44) arranged to receive the feedback signal and generate a digital error signal according to the feedback signal; and an output signal generating circuit arranged to generate the output signal and to receive the digital error signal and to adjust the output signal according to the digital error signal; the amplifier (1) further comprising: a fault detection circuit (50) arranged to receive the digital error signal and to determine the presence or absence of a fault condition at the amplifier output (7) according to the digital error signal and to provide a signal (54) indicative of the presence or absence of the fault condition.

Abstract: A digital amplifier (1) comprising a first modulation stage (9) arranged to receive a digital data signal and to generate a corresponding modulated reference signal; a comparator (12) arranged to receive a feedback signal and the modulated reference signal and generate a corresponding error signal (13) indicative of a difference between the modulated reference signal and the feedback signal; an integration stage (44) arranged to integrate the error signal (13) from the comparator (12) to generate an integrated digital error signal; a summer (19) arranged to receive the integrated digital error signal and the digital data signal (8) and generate an adjusted digital data signal indicative of their sum; an output stage comprising a second modulation stage, the output stage being arranged to receive the adjusted digital data signal and to generate a corresponding modulated output signal for driving a load (7); and a feedback circuit arranged to provide said feedback signal to the comparator (12), the feedback sig

Abstract: A method of controlling a brushless DC motor of the type having a stator, comprising a stator winding excitable to generate a stator magnetic field, and a rotor, arranged to rotate with respect to the stator and comprising permanently magnetised material arranged to generate a rotor magnetic field to interact with the stator magnetic field to produce rotation of the rotor. The method comprises the steps of driving current through the stator winding to generate a stator magnetic field to interact with the rotor magnetic field, detecting rotor position with respect to the stator, and cyclically commutating the stator winding current according to rotor position as the rotor rotates. Each commutation cycle includes a drive portion during which current is driven through the stator winding in one sense and at the end of which the driving of current in said sense is ceased.