A discharge circuit includes: a first transistor connected to power storage; an operational amplifier for controlling an output current of the first transistor; and the current mirror circuit connected to the operational amplifier. The current mirror circuit includes a second transistor connected to a non-inverting input terminal of the operational amplifier, and a third transistor connected to the power storage.

A power transfer device includes an oscillator circuit of a DC/AC power converter responsive to an input DC signal and an oscillator enable signal to generate an AC signal. The oscillator circuit includes a first node, a second node, and a circuit coupled between the first node and the second node. The circuit includes a cross-coupled pair of devices. The oscillator circuit further includes a variable capacitor coupled between the first node and the second node. A capacitance of the variable capacitor is based on a digital control signal. A first frequency of a pseudo-differential signal on the first node and the second node is based on the capacitance. The power transfer device further includes a control circuit configured to periodically update the digital control signal. A second frequency of periodic updates to the digital control signal is different from the first frequency.

A DC/DC converter comprises a transformer having a primary and a secondary, a winding of the primary forming part of a transformer power supply self-oscillating circuit. The primary side includes a controllable circuit that receives a first digital signal to be transmitted to the secondary, and a modulation device acting on the self-oscillating circuit. The secondary side comprises a detection and de-modulation circuit for recovering the first signal. The modulation device delivers a second signal that controls, via a switch, application of a first DC voltage across the self-oscillating circuit when the second signal is in a first state, the second signal comprising first pulse trains in a second state during first periods of the first signal. The detection and demodulation circuit comprises a device for reconstructing the first pulse trains of the second signal based on interruptions of energy recovered at the secondary, thereby deducing the first signal therefrom.

The present description concerns a DC/DC converter including: a transformer (2) having a primary winding (21) forming part of a self-oscillating circuit (6); a controllable circuit of application of a first DC voltage (Vin) across the self-oscillating circuit; and a circuit (8) of energy detection at the secondary (22) of the transformer.

The power supply control unit includes an on trigger signal generating unit arranged to generate an on trigger signal for turning on the switching element on the basis of a feedback signal of flyback voltage, a first timer arranged to measure a predetermined minimum OFF time, a second timer arranged to measure time based on an ON time, a minimum OFF time setting unit arranged to compare the predetermined minimum OFF time measured by the first timer with the time measured by the second timer so as to set a longer time as a minimum OFF time, and an on timing determining unit arranged to determine timing for turning on the switching element on the basis of the set minimum OFF time and the on trigger signal.

A DC-to-AC inverter provides an AC voltage to the primary winding of an output isolation transformer having at least one secondary winding. An AC output voltage from the secondary winding is rectified to generate a DC voltage, which is applied to a load. The magnitude of a current flowing through the load is sensed and compared to a reference magnitude to produce a feedback signal. The feedback signal controls a voltage superposition circuit, which produces a superposition voltage. The superposition voltage is applied to an input node of a current control circuit. The current control circuit responds to the superposition voltage to vary a magnitude of a control current to a switching controller in the DC to-AC inverter. The switching controller is responsive to the control current magnitude to vary the frequency of the AC voltage and to thereby vary the load current.

A switching power supply circuit, which keeps an output voltage constant highly accurately by a buck-boost action, is provided. The switching power supply circuit comprises: a switching circuit formed by combining four switching elements with a coil in the shape of H; a coil current emulation circuit for generating an output voltage VC similar to a coil current; and a control circuit which, based on a feedback voltage representing an output voltage VO of the switching circuit, and the output voltage VC, performs on-off control of the switching circuit. The coil current emulation circuit has a CR integration circuit to generate the output voltage VC similar to the coil current. One of three voltages is applied to one terminal of the CR integration circuit, while a voltage proportional to the output voltage VO is applied to the other terminal of the CR integration circuit. The three voltages are a voltage proportional to an input voltage VIN, a ground voltage, and a voltage proportional to the sum of the input voltage VIN and the output voltage VO.

A power transfer device includes an oscillator circuit of a DC/AC power converter responsive to an input DC signal and an oscillator enable signal to generate an AC signal. The oscillator circuit includes a first node, a second node, and a circuit coupled between the first node and the second node. The circuit includes a cross-coupled pair of devices. The oscillator circuit further includes a variable capacitor coupled between the first node and the second node. A capacitance of the variable capacitor is based on a digital control signal. A first frequency of a pseudo-differential signal on the first node and the second node is based on the capacitance. The power transfer device further includes a control circuit configured to periodically update the digital control signal. A second frequency of periodic updates to the digital control signal is different from the first frequency.

A power converter controller and methods for its operation are provided that can control a self-oscillating power converter that uses a Bipolar Junction Transistor (BJT) as a switch by manipulating the current flowing in a control winding. The controller is able to determine the optimum time to remove a short circuit applied to the control winding, as well as being able to determine the optimum time to pass current through the control winding. The controller can further draw power from the power converter using the control winding. The controller is capable of maintaining the midpoint voltage of the power converter in the case that the converter has more than one switch. The controller estimates the output power of the converter without requiring a connection to the secondary side of the converter transformer. The controller further controls entry and exit into a low-power mode in which converter oscillations are suppressed.

A device comprises a gate drive bridge coupled between a bias voltage of a power converter and ground and a transformer connected to the gate drive bridge, wherein the transformer comprises a primary winding connected to two legs of the gate drive bridge respectively and a plurality of secondary windings configured to generate gate drive signals for low side switches, high side switches and secondary switches of the power converter.