Short-circuit external characteristic realization circuit and external characteristic realization method

Abstract

The invention discloses a short-circuit external characteristic realization circuit and an external characteristic realization method. The method is applied to a switching power supply main power circuit. A current sampling circuit collects a current of the switching power supply main power circuit. The current is converted into a voltage signal V1 of 0-5v and the V1is transmitted to a current-limiting external characteristic signal generating circuit, and the current-limiting external characteristic signal generating circuit is used for carrying out differential amplification on an error between the V1 and a reference voltage to obtain an external characteristic control signal and outputting the external characteristic control signal to a negative electrode of a diode; an anode of the diode is connected with one end of a capacitor and an input end of a power control module; the other end of the capacitor is grounded; and the power supply control module generates a driving signal according to the V1 and the voltage on the capacitor, and acts on the switching power supply main power circuit so that a relationship between an output voltage and the current of the switching power supply main power circuit meets an external characteristic. The circuit is simple in structure and high in response speed, smooth switching between a voltage stabilization state and an overload state is achieved, and a situation of control disorder is avoided.

Description

technical field [0001] The invention belongs to the field of switching power supplies, and in particular relates to a short-circuit external characteristic realization circuit and a method for realizing the external characteristic. Background technique [0002] In some occasions, the power supply is required to still have enough output power under overload conditions, but at the same time it is necessary to limit the output power of the system to avoid damage due to local overheating. Therefore, an external characteristic curve needs to be realized. This requires the addition of a certain protection circuit to limit the power in the overload area. At the same time, the need has the characteristics of fast dynamic response, and it can also play a role in transient situations such as sudden short circuit to avoid instantaneous current shock. [0003] The circuits used in the prior art mainly realize current limiting through peak current control, which can only limit the peak...

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Problems solved by technology

[0004] Purpose of the invention: In order to solve the problem that it is difficult to specifically control the overall current-limiting external characteristics of the system in the prior art, the present invention provides a short-circuit external characteristic realization circuit and a method for realizing the external characteristics

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