A self-excited push-pull circuit and its auxiliary power supply method

Abstract

The present invention provides a self-excited push-pull circuit, which includes a main power circuit and an auxiliary power supply circuit. The main power circuit includes a triode TR1, a triode TR2 and a transformer T1. The output end of the auxiliary power supply circuit is electrically connected to the center tap of the auxiliary winding of the transformer T1. , used to provide base current for transistors TR1 and TR2, characterized in that: the input end of the auxiliary power supply circuit is electrically connected to the collector of the transistor TR1 and / or the transistor TR2, which can reduce the short circuit of the product while enhancing the load capacity of the product power consumption. Compared with the prior art, the circuit of the present invention has the characteristics of less loss, higher output voltage than the input voltage of the product, taking into account the load capacity of the product and short-circuit power consumption, etc. Within the voltage range and wide temperature range, it can better meet the load capacity of the product and reduce the short-circuit power consumption under the short-circuit state of the output end of the product.

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 electricity from a triode collector. Background technique [0002] The self-excited push-pull topology is widely used in micro power supply applications 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 a constant voltage input open-loop feedback type, and the other is a closed-loop feedback voltage regulation type. [0003] like figure 1 As shown, 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...

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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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