A method for limiting a switching current and limiting a voltage drop across a circuit includes the steps of limiting a current sent from a power source to a switching device during a turn on time of the switching device by disposing an inductor device in series between the power source and said switching device and returning flux energy stored in said inductor device to the power source during a turn off time of the switching device.

A switching type converter including an input stage and an output stage, the input stage including an input inductor to which an input DC voltage to be regulated is applied, switching component for directing the current passing through the input inductor either to the ground or to the output stage, and a capacitor mounted in parallel between the output from the switching component and the ground, the output stage including an output inductor mounted in series, an output capacitor mounted in parallel, the terminals of which carry the output voltage from the regulator, and an additional inductor connecting the output of the switching component to the output stage and magnetically coupled to the input inductor.

A voltage regulator for DRAM chips having known short duration high current load events started by a trigger signal includes a regulating transistor operating in the weak inversion mode and a boost driver circuit. The trigger signal that starts the load event also triggers the boost driver circuit to produce a shaped boost signal at the correct time. The boost signal is applied to the gate of the regulating transistor to counteract the expected voltage drop at the output of the regulating transistor. The expected voltage drop is due to the known characteristics of the regulating transistor which include a change in threshold voltage of the regulating transistor during the high current flow of the load event. A switch device disconnects a preregulator during the load event and reconnects the preregulator thereafter. The boost signal is preferably applied to the regulating transistor through a capacitive divider.

An inductor 6 accumulates an energy therein or releases the accumulated energy according to the state of a main switch element 10 being turned ON/OFF. When the inductor 6 releases an energy, if a sub-switch element 12 is in the ON state, a current is passed through a circuit downstream of the sub-switch element 12, thereby increasing an output voltage VO1. The sub-switch element 12 is a P-channel MOS transistor, and a sub-switch control circuit 18 outputs a control signal VCT1 for the sub-switch element 12. A level shift circuit 19 receives an output-side potential VP of the inductor 6, and outputs, as a control signal VG1 applied to the gate of the sub-switch element 12, the potential VP if the control signal VCT1 is at the L level or a potential (VP-VM) lower than the potential VP if the control signal VCT1 is at the H level. Thus, the output voltage of the DC-DC converter can be made precisely equal to the target voltage.

The invention finds application in the field of power supplies for valve actuators, and particularly relates to a wide voltage range stabilized switching power supply for valve actuators, of the type that comprises a filter 2, a diode bridge 3, an array of capacitors 5, an auxiliary power supply stage 6, formed by a switch mode circuit, having an operating range of 21 to 380 VDC, which generates the supply voltages required for the internal operation of the power supply, a full-bridge power stage 7, which receives an input voltage in the range of 120 VDC to 373 VDC, and generates the three stabilized output voltages required for supplying the load, and a boost stage 4, located upstream from the power stage 7, which allows to increase the voltage to a value in the range of 120 VDC to 373 VCC, whenever it is below such range.