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Improved EoL protection circuit based on UBA2013 Disclosure Number: IPCOM000124982D
Publication Date: 2005-May-17
Document File: 3 page(s) / 53K

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The Prior Art Database



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Publication ID869678

Improved EoL protection circuit based on UBA2013

Usually circuits shown in Fig. 1 are used to simulate rectifying state of lamp load and test the function of EoL protection circuits in Ballasts. Connecting the load with ballasts, EoL protection circuits will be triggered, and the trigger level is set by the power on load represented by a resistor R. The power can be PR=UR*IR. In practical design process, the trigger level is limited in the range: 5.0W<PR<10W. In different rectifying condition, the parameter PR must be ensured as the former formula. If PR is smaller than 5.0W, then it means that the EoL protection circuits are so sensitive; else if PR is larger that 10W, the protection circuits are not sensitive enough.


In the figure 2, EoL protection circuits based on UBA2013 are shown, where Clow is the low part of half-bridge capacitors. Voltage of point G will fluctuate with the depth of rectifying state, and then voltage of EoL pin will also increase or decrease. Refer to the specification of UBA2013, it is known that EoL protection circuit will be triggered and protection function will operate when voltage of EoL pin is higher than Veol(high) (nearly

3.0V) or lower than Veol(low) (nearly 2.0V). In normal load condition where there is no rectifying state, Veol(normal) is set as 2.5V.

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For the protection circuit base on UBA2013 in fig.2, in normal condi...