Protective circuit while no lamp tube cut-in in electronic ballast

Abstract

This invention discloses a protection circuit in a ballast when no lamp tube is cut-in including a first comparator, its input positive terminal samples the supply lead-in end voltage of the second filament of the lamp, the output end is connected to the supply of the oscillation drive circuit of the lamp by a MOS tube, the lead-out end of the second filament is serial to a risistor then to connect the earth. When the lamp works normally, the input negative voltage of the first is higher than the positive and low level is output , the MOS tube is stopped, the oscillation drive circuit works normally. When there is no lamp in the circuit the input negative voltage of the first is lower than the positive and high level is output, MOS is turned on, its source voltage is zero, the supply voltage of the drive circuit is zero and stops oscillating, the circuit is protected.

Description

technical field [0001] The invention relates to a protection circuit of an electronic ballast, in particular to a protection circuit when no lamp tube is connected to the electronic ballast. Background technique [0002] Today's electronic ballasts are more and more widely used, and the requirements for electronic ballasts are getting higher and higher, especially some protection functions, especially the appearance of T5 and other small-diameter products, which have a great impact on the end of life and lifeless The protection requirements of the lamp are particularly prominent. At present, the protection when the lamp is end of life or no lamp is connected, and the technology of automatic restart after the lamp is replaced usually uses a chip circuit. For example, the ballast protection circuit of PHILPS uses a 2010T chip. technology, but the circuit is more complex. At present, there is no protection circuit in China when no lamp is connected, and there is a restart tech...

AI Technical Summary

Problems solved by technology

[0002] Today's electronic ballasts are more and more widely used, and the requirements for electronic ballasts are getting higher and higher, especially some protection functions, especially the appearance of T5 and other small-diameter products, which have a great impact on the end of life and lifeless The protection requirements of the lamp are particularly prominent. At present, the protection when the lamp is end of life or no lamp is connected, and the technology of automatic restart after the lamp is replaced usually uses a chip circuit. For example, the ballast protection circuit of PHILPS uses a 2010T chip. technology, but the circuit is more complex

At present, there is no protection circuit in China when no lamp is connected, and there is a restart technology for air leakage protection, but it is set to a fixed time to restart continuously, and then continue to protect until the lamp is replaced. In this way During the time when the lamp is not changed, the ballast will be damaged to a certain extent. At the same time, if the restart time is not set enough, there will be a certain danger when changing the lamp.

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