Primary-side controlled flyback power converter
USRE40656E1 · kind E1 · reissue
Assignee
Inventors
Key dates
| Filing date | Apr 24, 2006 |
| Grant date | Mar 10, 2009 |
| Priority date | — |
| Expiry date | Apr 24, 2026 |
Classification
- Technology area (CPC —)General
Abstract
The present invention provides a primary-side flyback power converter that supplies a constant voltage output and a constant current output. To generate a well-regulated output voltage under varying load conditions, a PWM controller is included in the power converter in order to generate a PWM signal controlling a switching transistor in response to a flyback voltage sampled from a first primary winding of the power supply transformer. Several improvements are included in this present invention to overcome the disadvantages of prior-art flyback power converters. Firstly, the flyback energy of the first primary winding is used as a DC power source for the PWM controller in order to reduce power consumption. A double sample amplifier samples the flyback voltage just before the transformer current drops to zero. Moreover, an offset current is pulled from a detection input of the double sample amplifier in order to generate a more accurate DC output voltage. The offset current is generated in response to the temperature in order to compensate for temperature-induced voltage fluctuations across the output rectifier. Ultimately, in order to maintain a constant output current, the PWM con…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.