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Driven strengthen circuits with universal input base on UBA2013 Disclosure Number: IPCOM000124983D
Publication Date: 2005-May-17
Document File: 2 page(s) / 37K

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The Prior Art Database



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Publication ID869679

Driven strengthen circuits with universal input base on UBA2013




VO Ton









TOFF timing



In the figure below, refer to datasheet of UBA2013, driven signal of Mup in PFC circuits is supplied by the secondary winding of Boost choke but by IC. When current in freewheeling diode D1 is reduced to zero, reverse recovery current will flow through primary winding of Boost choke. Voltage on secondary winding turns positive from negative, and Mup is turned on. The conduction state is supplied by the voltage on the secondary winding of Boost choke, and concurrently gate voltage of Mup is detected by pin G/ZCD. If VGZCD is larger than VGZCD(start), ton timer starts timing and will not reset until VGZCD is smaller than VGZCD(start).

At the end of ton, inside IC driver Pin ZCD is pulled to ground at a fixed time toff, and Mup is turned off. Then current flows through primary winding of Boost choke and D1, and negative voltage on secondary winding maintain the off state of Mup. The process will repeat in the next switching period.

What are the drawbacks of this?

1.The driven circuit is not fit for the application with universal line input. Mup is maintained on or off through the inductive voltage on secondary winding of Boost choke.

Gate voltage must be larger than 12 volts to ensure the reliable conduction of MOSFET, and that means secondary voltage of Boost choke must larger than 12V. In universal input, primary voltage of Boost choke is only 120V in 120V input, then the turns ratio must be 10:1 or 6:1. Therefore, in 277V input, secondary voltage will be very high and loss of driving resistor R1 is so large.


From RS,up

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2.Threshold voltage of Mup usually is lower than VGZCD(start) (nearly 5V). A...