Self-excitation push-pull circuit and auxiliary power supply method thereof

Abstract

The invention provides a self-excitation push-pull circuit. The self-excitation push-pull circuit comprises a main power circuit and an auxiliary power supply circuit, the main power circuit comprisesa triode TR1, a triode TR2 and a transformer T1, and the output end of the auxiliary power supply circuit is electrically connected with the center tap of an auxiliary winding of the transformer T1 to provide base current for the triode TR1 and the triode TR2. The input end of the auxiliary power supply circuit is electrically connected with the collector of the triode TR1 and / or the triode TR2,so that the short-circuit power consumption of the product can be reduced while the load capacity of the product is enhanced. Compared with like circuits in the prior art, the circuit provided by theinvention has the characteristics of low loss, higher output voltage than the input voltage of a product, consideration to the load capacity and short-circuit power consumption of the product and thelike, is particularly suitable for a low-voltage input state, and can be used in a wider input voltage range and a wider temperature range; and the product loading capacity is better met, and the short-circuit power consumption of the output end of the product in a short-circuit state is reduced.

Description

technical field [0001] The invention relates to the field of switching power supplies, in particular to a self-excited push-pull circuit and an auxiliary power supply method for taking power from a triode collector. Background technique [0002] Self-excited push-pull topology is widely used in micro power supply occasions because of its simple circuit and low switching noise. According to the application requirements of different occasions, the self-excited push-pull topology can be roughly divided into two types of manifestations, one is the constant voltage input open-loop feedback type, and the other is the closed-loop feedback regulator type. [0003] Such as figure 1 As shown in , the schematic diagram of the circuit is a constant voltage input open-loop feedback type, which is a widely used topology representation, including input filter circuit, main power circuit, rectifier circuit and auxiliary power supply circuit. The working principle of the circuit is a known...

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Problems solved by technology

When the input voltage of the product is small and the output voltage of the required auxiliary power supply circuit is large (in order to ensure that the product meets the load capacity), the above two auxiliary power supply circuit schemes cannot meet the circuit design requirements.

[0014] 2. In the self-excited push-pull topology, in general, the stronger the load capacity of the product, the greater the short-circuit power consumption when the product is short-circuited at the output end, resulting in reduced reliability of the product and increased risk of product failure

The two auxiliary power supply circuit schemes mentioned above cannot simultaneously solve the two contradictory design difficulties of strong load capacity and low short-circuit power consumption.

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