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 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: For use with a power converter, a bias voltage generator samples a fraction of the input voltage Vin using a bias switch coupled to a tap on the power converter transformer input winding. The bias switch is driven from the same control circuit that drives the converter switch, and the fraction of Vin sampled by the bias switch is coupled to a low pass filter to generate the bias voltage Vbias. Vbias≈(Vin)·(Kf)·(Kdc), where Kf is the fractional location of the transformer tap, and Kdc is duty cycle of the power converter switch. Vbias enjoys automatic compensation against variation in Vin because the power converter will automatically compensate Kdc to correct for Vin variation. The resultant bias voltage generator requires no additional transformer winding.

Abstract: The input side of a DC:DC converter emulates current fed topologies and replaces an active switch and associated components with a passive inductor, coupled between Vin and upper nodes of the primary transformer windings, that smoothes input current. Several output side topologies are disclosed that may be used with any input side configuration, and require no output snubbers. The output topologies use non-center-tapped secondary windings that are utilized 100% of the time. The output topologies advantageously use series-coupled capacitors, which configuration distributes voltage stress. The topologies advantageously provide two output voltages, Vo1 and Vo2≈Vo1, or Vo2≈−Vo1. The snubber-less output side topologies provide very low EMI content waveforms that may be switched at relatively high frequencies.

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 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.