Abstract: A switching regulator target voltage is adjusted to a first value corresponding to a pre-charge voltage that is present at a regulator output terminal. The switching regulator responds to a comparison signal resulting from a comparison of the target voltage and a feedback voltage. When the switching regulator is on, the target voltage is adjusted to a second value corresponding to a nominal regulator output voltage. In one embodiment, a synchronous switch is disabled when a lockout circuit receives a disable signal. The lockout circuit is unlocked when an enable signal is provided by a switching controller.

Abstract: Switching circuits including DC:DC converters of various topologies are provided with a soft-start mechanism that ensures safe start-up operation. The mechanism causes the converter switches to be driven such that on-impedance is increased during at least a portion of the time the switches are turned on. Increased on-impedance condition is invoked during power-up, and/or no-load or light-load condition. The increased on-impedance temporarily reduces output voltage and/or drive current provided by the converter.

Abstract: The output-side referenced pulse width modulator (PWM) in an isolation-providing voltage converter receives at least initial bias voltage (Vbias) from a charge-pump like Vbias generator. The Vbias generator includes an input-side referenced periodic waveform generator whose output signal can be amplified differentially with an input-side referenced circuit and then AC-coupled via isolation-maintaining capacitors to an output-side referenced rectifier circuit whose output is Vbias. The Vbias thus generated can power the PWM at least from power-up through commencement of steady-state operation, when a more robust Vbias can be derived from the output-side voltage itself. Since the PWM is output-side referenced, high feedback bandwidth is maintained.

Abstract: The output-side referenced pulse width modulator (PWM) in an isolation-providing voltage converter receives at least initial bias voltage (Vbias) from a charge-pump like Vbias generator. The Vbias generator includes an input-side referenced periodic waveform generator whose output signal can be amplified differentially with an input-side referenced circuit and then AC-coupled via isolation-maintaining capacitors to an output-side referenced rectifier circuit whose output is Vbias. The Vbias thus generated can power the PWM at least from power-up through commencement of steady-state operation, when a more robust Vbias can be derived from the output-side voltage itself. Since the PWM is output-side referenced, high feedback bandwidth is maintained.

Abstract: A switching power supply produces a regulated output voltage. An output inductor is connected at one end to a power switch circuit having a duty cycle. The other end of the output inductor has a regulated output voltage. A voltage feedback circuit produces a voltage feedback signal representative of the regulated output voltage. A current feedback circuit produces a composite signal representative of inductor current, the composite signal having an ac component and a dc component. An error amplifier produces an error signal representative of the difference between a reference voltage and the voltage feedback signal. A pulse width modulator comparator compares the error signal to a composite signal representing a summing of the voltage feedback signal with a current sensing signal representative of output inductor current, the composite signal having an ac component and a dc component.

Abstract: A generic voltage converter outputs at least two voltages: a Vo potential that is regulated using output-to-input feedback to a PWM that controls duty cycle of the converter switch, and a VoAUX potential available from a post-linear regulator. Output-to-input feedback is provided from the post-linear regulator to a node in the PWM, e.g., COMP, SoftStart, VFB. Whenever the post-linear regulator senses excessive VoAUX current, feedback from the regulator commands the PWM to reduce converter duty cycle, which reduces VinAUX, as well as VoAUX and Vo, without cross-regulation. The topology minimizes thermal dissipation within the regulator pass element by saturating the pass element at maximum VoAUX current flow such that at maximum current flow there is minimal voltage drop across the pass element.

Abstract: A pseudo-push-pull DC:DC converter topology replaces one primary switching transistor with a high speed passively switched diode coupled between one end of a transformer first primary winding and ground. A second primary winding is coupled to ground via a solid state switch that is driven with a control circuit that outputs a single drive signal of slightly less than 50% duty cycle. The other ends of the first and the second transformer primaries are coupleable to a source of Vin. The topology includes a gapped transformer whose transformer core stores sufficient electromagnetic energy when the solid state switch is turned-on by the control circuit to drive a load coupled to the transformer secondary when the solid state switch is turned-off. When the solid state switch is turned-off by the control circuit, the diode self-biases on, coupling the first transformer primary winding between Vin and ground, as though a perfectly driven solid state switch were turned-on.

Abstract: A method and circuit arrangement for sensing the output current in a switch mode power converter in order to provide protection arrangements which are responsive to overload or short circuit conditions. In a switch mode power converter including an inductor for providing output current to a load circuit, the inductor having an inherent resistance, a filter circuit is coupled to both the first terminal of the inductor and to the second terminal of the inductor. The filter circuit provides the DC component of the voltage across the inherent resistance of the inductor to an error amplifier. The error amplifier provides an output signal representing the output current, and the output signal is used to adjust an operating parameter of the switching circuit, e.g. duty cycle.

Abstract: A fault protection arrangement for protecting power conversion circuits, for example switch mode power supplies and the like, from overcurrent and short circuit faults. The fault protection arrangement includes multiple fault protection features, for example soft-start delay, fault delay and automatic reset, with the timing of each of these three features capable of being set independently of the other two while minimizing integrated circuit (IC) pin count and also minimizing the number of external components required for programming the timing of these features. The fault protection circuit may be used to advantage with any power conversion regulator topology.

Abstract: A switching regulator and a method of regulating voltage by means of a switching regulator, includes a regulator switch, a smoothing filter, and a first voltage feedback loop from an output of he regulator to a control line of the switch. The first feedback loop may include a hysteresis comparator or a comparator and a frequency reference connected to the control line of the switch. The first feedback loop uses the A.C. ripples at the output of the smoothing filter as a ramp signal feedback to substantially instantaneously correct output voltage. A second voltage feedback is further employed to stabilize the output voltage. The smoothing filter employs an LC circuit and the regulator is provided with means for providing an inductor current path when the switch is opened. The regulator may, further, include a current feedback loop.

Abstract: A switching voltage regulator is described which provides multiple independently regulated outputs. A switch control independently monitors two or more voltage outputs and generates control signals for driving a main switch and two or more auxiliary switches to charge selective ones of the outputs which have fallen below their target voltages. Time sequencing techniques are utilized to control the switching of the auxiliary switches such that energy stored in an inductor is transferred to the appropriate voltage outputs. The switching voltage regulator may be implemented as an integrated circuit and may have various topologies, such as boost, buck, flyback or SEPIC.