Abstract: A buck or boost converter, which includes a first inductor, a controlled switch, a main diode, and an output capacitor, also includes a snubber circuit to reduce losses. The snubber circuit includes a second inductor in a path in series with the switch and main diode of the converter, a series-connected resistor and diode connected directly in parallel with the second inductor, and a capacitance in parallel with the main diode and which can be constituted partly or entirely by parasitic capacitance of the main diode.

Abstract: A buck or boost converter, which includes a first inductor, a controlled switch, a main diode, and an output capacitor, also includes a snubber circuit to reduce losses. The snubber circuit includes a second inductor in a path in series with the switch and main diode of the converter, a series-connected resistor and diode connected directly in parallel with the second inductor, and a capacitance in parallel with the main diode and which can be constituted partly or entirely by parasitic capacitance of the main diode.

Abstract: A DC converter comprises a single primary circuit which is coupled to each of a plurality of output circuits in respective time periods, the coupling being provided by switching in the output circuits. Each output circuit produces a respective output voltage and a respective feedback signal which is coupled as a control signal to the primary circuit during the respective time periods, so that each output voltage is regulated substantially independently of each other output voltage. The time periods for the different output circuits can be equal or different, and can be dynamically changed depending on error voltages of the output circuits.

Abstract: A plurality of cold cathode fluorescent lamps (CCFLs) for a backlight of a display device are connected, each in series with a respective variable inductance, in parallel to an AC supply from a power converter. Each variable inductor comprises a first inductor in series with the CCFL, a second inductor inductively coupled to the first inductor, and an AC switch for selectively shorting the second inductor. A capacitor in parallel with the first inductor forms a resonant circuit tuned to the AC supply frequency when the switch is open. Each switch is opened and closed with a controlled duty cycle to provide individual control of an average current of each CCFL.

Abstract: An inductor in a series path of a DC converter having a buck or boost configuration is constituted by a transformer with windings in series with switches of the converter. A transformer turns ratio facilitates matching switch voltage and current stresses to characteristics of MOSFETs forming the switches. A high side MOSFET can have its source at a constant voltage to facilitate driving this switch. One switch can be replaced by a diode. A transformer leakage energy removal circuit can provide an auxiliary output voltage, greater than the input voltage for a buck configuration.

Abstract: A digital controller for a DC converter has a timing and control unit which produces a control pulse signal with varying duty cycle and frequency in accordance with pulse on- and off-times determined by digital values read from a look-up table addressed via an A-D converter in dependence upon an input voltage for the DC converter. The stored digital values are such that a period of the control pulse signal varies over a range of about two-thirds to about four-thirds of a nominal value. Closed loop feedback control can be added by modifying addressing of the look-up in dependence upon an error signal from the DC converter output voltage, with scaling depending on the input voltage.