A power transistor and a cascode transistor are connected in series. A driver circuit has an output driving a control terminal of the power transistor. The driver circuit has a first power supply node coupled to receive a floating voltage that is also applied to a control terminal of the cascode transistor. A variable voltage generator generates the floating voltage. The floating voltage track either a power supply voltage or a reference voltage over a first range of voltage levels for the power supply voltage. The floating voltage further satisfies a ratio metric relationship dependent on the power supply voltage and reference voltage over a second range of voltage levels for said power supply voltage.

A power supply comprises a power converter having a transformer, a low side switch configured to draw current from a supply voltage through a primary winding of the transformer and a high side switch configured to couple the primary winding of the transformer to a snubber capacitor. A controller is configured to control the power converter by generating drive signals that control the opening and closing of the high side switch and the low side switch. The controller is configured to selectively control the high side switch according to various modes of operation depending on operating conditions such as input voltage and load power consumption. The modes of operation can include, for example, a mode in which the high side switch is closed and then opened once during each of the series of switching cycles and a mode of operation in which the high side switch is closed and then opened two times during each of the series of switching cycles.

There is presented a driver and a corresponding method for driving a p-type power switch. The driver includes a capacitor coupled to a control terminal of the power switch. The driver is configured to apply a control voltage to the control terminal and to connect the control terminal to ground to reduce the control voltage down to a target value to switch the power switch on. When identifying that the control voltage has reached the target value, the driver disconnects the control terminal from ground. The driver may be used in various circuits including switching power converters, audio amplifiers and charge-pump circuits.

A switching regulator converts an AC input voltage into an output voltage, to power a load. The switching regulator includes a power stage having a main power switch. The main power switch has different ON time durations under different AC input voltage conditions and different load currents.

This disclosure describes a protection circuit configured to protect a power converter. The protection circuit may be configured to determine when the power converter is operating in a tristate mode, and upon determining that the power converter is operating in the tristate mode, to disable a supply to the power converter based on a comparison of a switch node voltage on a switch node of the power converter to a feedback node voltage on an output node of the power converter.

Apparatus and methods for supplying DC power to control circuitry of a matrix converter is provided. In certain embodiments, a matrix converter includes an array of switches having AC inputs for receiving a multi-phase AC input voltage and AC outputs for providing a multi-phase AC output voltage to a load, such as an electric motor. The matrix converter further includes control circuitry for opening or closing individual switches of the array, and a clamp circuit connected between the AC inputs and AC outputs of the array and operable to dissipate energy of the load in response to an overvoltage condition, such as an overvoltage condition arising during shutdown. The clamp circuit includes a switched mode power supply operable to generate a DC supply voltage for the control circuitry.

A high-side driving circuit drives a high-side transistor configured as an N-channel or NPN transistor, according to an input signal. A level shift circuit level shifts the input signal. A latch stabilization circuit selects one node that corresponds to an output of the level shift circuit, from among a first node and a second node configured as complementary nodes provided to a latch circuit, and sinks a current from the node thus selected.

A power converter includes: a switching transistor, a transformer, a control circuit; the control circuit is configured to determine a target voltage in a process that the switching transistor is driven to conduct; the target voltage can represent a voltage change of an input terminal of the switching transistor; when the target voltage starts to drop but is higher than a reference voltage, drive a control terminal of the switching transistor with a first driving current; when the target voltage decreases to be lower than the reference voltage, drive the switching transistor with a second driving current; the second driving current is higher than the first driving current; the switching transistor is driven by the first driving current for part or all of the time before entering the Miller plateau stage, and is driven by the second driving current after starting to enter the Miller plateau stage.

A bootstrap circuit unit of a DC-DC converter applies, to a drive unit, a voltage that is higher than that at a first connection point between switching elements in a first conversion operation, and applies, to the drive unit, a voltage that is higher than that at a second connection point between switching elements in a second conversion operation. A charge-pump circuit unit steps up an input voltage and applies the resulting voltage to the drive unit. The drive unit sets the voltage of a first drive signal and a second drive signal according to a voltage applied by the bootstrap circuit unit or a voltage applied by the charge-pump circuit unit. The charge-pump circuit unit determines the operation timing at which the charge-pump circuit unit is to apply the output voltage, based on the first and second voltage, and the first and second power supply unit charging signals.

This DC/DC conversion system is provided between a plurality of DC power supplies and a common DC bus, and includes, for each of the plurality of DC power supplies: a DC/DC converter provided between the DC power supply and the DC bus; and a control unit configured to control the DC/DC converter. The control unit corrects a voltage detection value for the DC bus by taking in an individual voltage detection deviation for the DC bus compared to an entirety of a plurality of the DC/DC converters present in parallel, and controls the corresponding DC/DC converter in accordance with a voltage command value having droop characteristics with respect to output power. The DC/DC conversion system as described above can uniform outputs while operating the plurality of DC/DC converters in parallel without the need of fast communication.