In the power supply device, the insulated transformer transforms the voltage of alternating-current power. The rectifying circuit rectifies the alternating-current power transformed by the transformer to direct-current power. The smoothing inductor smoothes the direct-current power rectified by the rectifying circuit. The first output terminal outputs the direct-current power smoothed by the smoothing inductor. The second output terminal is a terminal different from the first output terminal and outputs the direct-current power smoothed by the smoothing inductor. An FET is provided between the smoothing inductor and the first output terminal and adjusts a current output from the smoothing inductor to the first output terminal. An FET is provided between the smoothing inductor and the second output terminal and adjusts a current output from the smoothing inductor to the second output terminal. The controller controls the FET and the FET.

A power device driving method and a driving circuit for a switching circuit having a main switching transistor, a synchronous rectifier, and an inductive element. When a switching signal indicates that the synchronous rectifier is turned from on to off and the main switching transistor is turned from off to on, a gate voltage of the synchronous rectifier is pulled down to be lower than a threshold voltage of the synchronous rectifier and higher than zero voltage by a body effect of a MOS transistor, and timing is started. When detecting that a gate voltage of the main switching transistor rises to a first voltage or the timing reaches a first time, the gate voltage of the synchronous rectifier is pulled down to the zero voltage.

The present application provides a power conversion device such that input current and output current can be accurately estimated without providing a special circuit. A DC-DC converter including a control unit and semiconductor switching elements is such that a current detecting current transformer is connected in series between a high voltage battery and the semiconductor switching elements, in addition to which the DC-DC converter includes a current-to-voltage conversion circuit on a secondary side of the current transformer, and the control unit estimates an input current from an AD conversion value input from the current-to-voltage conversion circuit.

A multi-output power supply device includes an inductor, a first output terminal, a second output terminal, an FET, an FET, a chopper circuit, and a controller. The FET adjusts a current output from the inductor to the first output terminal. The FET adjusts a current output from the inductor to the second output terminal. The chopper circuit has the FET and the inductor. The FET is connected in parallel with the FET, and conducts or cuts off a current. The inductor is provided between the FET and the second output terminal. For example, the controller lowers a potential from the first output terminal by turning on the FET and sets a potential difference between a drain terminal and a source terminal of the FET to zero to suppress a switching loss when the FET is turned on.

In a rectifying circuit including a HEMT and a diode connected antiparallel to the HEMT, a forward voltage drop when the diode starts to be conductive is made smaller than a voltage drop when the HEMT is reverse-conductive in an OFF state corresponding to an amount of rectified current when the HEMT is reverse-conductive in an ON state, inductance of a pathway extending through the diode is made larger than inductance of a pathway extending through the HEMT among the pathways connecting a source terminal and a drain terminal of the HEMT, and an amount of charge accumulated in a parasitic capacitance of the diode is made smaller than an amount of charge accumulated in an output capacitance of the HEMT. With this, there is provided a rectifying circuit in which switching loss due to the charge accumulated in the output capacitance of the HEMT is reduced.

An automatic dead zone time optimization system in a primary-side regulation flyback power supply CCM mode, comprising a closed loop formed by a control system, consisting of a single output DAC midpoint sampling module, a digital control module, a current detection module, a dead zone time calculation module and a PWM driving module, and a controlled synchronous rectification primary-side regulation flyback converter. By means of a DAC Sampling mechanism, a primary-side current is sampled to calculate a secondary-side average current, so as to obtain a primary-side average current Imid_p and a secondary-side average current Is(tmid) in the case of CCM; a secondary-side current is input into the dead zone time calculation module to obtain a reasonable dead zone time td; and finally, the PWM driving module is jointly controlled by a primary-side regulation loop and the obtained dead zone time td.

A method of controlling synchronous rectification transistors in a switching converter includes sensing a drain-to-source voltage across each synchronous rectification transistor each switching half-cycle of the switching converter. An average of the sensed drain-to-source voltage is calculated for each synchronous rectification transistor over N prior switching half-cycles. A load current transient in the switching converter is sensed based on the sensed drain-to-source voltage of each synchronous rectification transistor and the calculated average of the sensed drain-to-source voltage for each synchronous rectification transistor over the N prior switching half-cycles.

A method of controlling synchronous rectification transistors in a switching converter includes sensing a drain-to-source voltage across each synchronous rectification transistor each switching half-cycle of the switching converter. An average of the sensed drain-to-source voltage is calculated for each synchronous rectification transistor over N prior switching half-cycles. A load current transient in the switching converter is sensed based on the sensed drain-to-source voltage of each synchronous rectification transistor and the calculated average of the sensed drain-to-source voltage for each synchronous rectification transistor over the N prior switching half-cycles.

In one embodiment, a DC/DC converter includes: a first switching element, a diode connected to the first switching element, an inductor connected to at least one of the first switching element and the diode, and a circuit connected in parallel to the first switching element, the circuit including a second switching element. A current flowing through the circuit when the second switching element is on is smaller than the current flowing through the first switching element when the first switching element is on, and the second switching element is turned on a lead time before the timing at which the first switching element is turned on.

The present disclosure, in an aspect thereof, has an object to effectively reduce transient current in a rectifier circuit. In a rectifier circuit, a current flows from a power supply to a coil when a transistor is turned on. Then, when the transistor is turned off, a second rectifier current flows from the coil to a second rectifier, and a first reverse voltage is applied across the rectifier circuit.