Texas Instruments Corporation

Texas Instruments (cork) Limited

Colin Gillmor

George Young

Bernard Keogh

A transformer-coupled gate-drive power regulator system is provided that includes a feedback stage that generates a PWM signal having a duty-cycle that is based on a magnitude of an output voltage in an output stage. A switch driver stage configured to provide each of a first control signal and a second control signal based on the PWM signal. A switching stage comprising a first transformer input stage, a second transformer input stage, and a control switch. The first transformer input stage activates the control switch via the first control signal while the second transformer input stage is deactivated, and the second transformer input stage activates the control switch via the second control signal while the first transformer input stage is deactivated. The control switch can be configured to provide current through an output inductor in the output stage to generate the output voltage in response to being activated.

Transformer-coupled gate-drive power regulator system

A sensing arrangement and method a sense winding is used to provide a voltage which represents the voltage appearing across an in-circuit magnetic component. In a flyback phase, when the component is supplying the output, that voltage represents an output voltage and in a supply phase, the supply voltage. This arrangement provides a solution to the problem of the disparity in magnitude of sense winding output during the two phases by proving a pull-up resistor arranged to apply bias to the voltage measured, the pull-up being to a first level during the supply period and to a second value during the flyback period, the first and second levels being selected such that the voltage across the sense winding is scaled differently during the supply period and the flyback period. The invention is suitable for use in a transformer based flyback power converter in which the magnitude disparity problem may be exacerbated by a turns ratio.

Primary-side sensing arrangements for power converters

The present invention provides an isolated regulating power converter with opto-coupled feedback of output (Vo) with respect to a reference level (Vset) for regulation to a converter controller. The sense of the feedback signal is such that the opto-coupler LED is ON when Vo&#x3c;Vset and OFF when Vo&#x3e;Vset with the effect that the LED current and power loss is zero during the times when Vo&#x3e;Vset, as is normal case for many controllers at low or no load. This saves power under such circumstances. Additionally, as the LED does not load the output during this time, the proportion of time for which Vo&#x3e;Vset is increased, meaning that the timing at which the switch must again be on to meet demand is extended, producing a further power saving.

Opto-coupled sensing

A power converter for delivering power to a load at a regulated voltageincludes a regulating stage receiving an unregulated supplyand having a main transformer. Switchesandare arranged in a half-bridge connect the transformer primaryto the unregulated supplyto drive the load via a rectifying stage connected to the transformer secondary. The on-time of the switch is controlled by a controllerto effect the regulation over a range of values of the unregulated supply. An auxiliary transformerhas a secondary windingconnected in series with the main transformer primaryand a primary winding that is selectively driven via a switch. A comparatordetects a low voltage event within the regulating stage, such as a drop in the intermediate voltage at. The primary windingof the auxiliary transformeris driven during the low voltage event.

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Limerick, Ireland

Colin Gillmor