CN213338479U - Parameter-adjustable switching power supply feedback loop - Google Patents

Abstract

The utility model discloses a parameter adjustable switching power supply feedback loop, including error amplifier U1, resistance R1, electric capacity C1 and electric capacity C2, resistance R1 and electric capacity C1 establish ties between error amplifier U1's reverse input and output, electric capacity C2 is parallelly connected with resistance R1 and electric capacity C1, parallelly connected regulating circuit on the electric capacity C2, the regulating circuit comprises MOS pipe Q1, resistance R3, electric capacity C3 series connection, MOS pipe Q1's switching receives singlechip drive control. Has the advantages that: switching power supply feedback loop can be according to switching power supply's application environment independently adjust the loop parameter, increase and decrease zero point, the utmost point number in the feedback loop then to the realization lasts for switching power supply provides stable output in full input voltage scope and full load range, has also satisfied switching power supply high dynamic characteristic's requirement simultaneously, the practicality is good.

Description

Parameter-adjustable switching power supply feedback loop

Technical Field

The utility model relates to a switching power supply feedback loop field, concretely relates to parameter adjustable switching power supply feedback loop.

Background

In recent years, the requirements of the industry for switching power supplies are getting higher and higher, and the requirements are embodied in that the input voltage range is wide, the output load range is wide, the dynamic characteristic is high, and the like, which brings a serious test to the stability of the feedback loop of the switching power supply, in the general loop design, in order to make the open loop gain at low frequency as large as possible (to filter low-frequency ripples at 100 Hz), and the open loop gain at high frequency as low as possible (to prevent high-frequency noise oscillation), a resistor is generally used to connect a capacitor in series, and connect a capacitor in parallel to form a negative feedback circuit, and then a type 2 error amplifier is formed in cooperation with the error amplifier, the classical amplifier circuit with a simple structure can be applied to most power supply loops, but some efforts are not good in some switching power supplies with wide input voltage range, wide output load range and very high dynamic characteristic requirements, it is impossible to continuously provide a stable output for the switching power supply.

Based on this, the utility model is designed.

SUMMERY OF THE UTILITY MODEL

The utility model aims at solving the problem in the above-mentioned background art and providing a parameter adjustable switching power supply feedback loop, this switching power supply feedback loop can be according to switching power supply's application environment autonomic regulation loop parameter, increases zero point, the limit number in the feedback loop to the realization lasts for switching power supply provides stable output in full input voltage scope and full load range, has satisfied switching power supply high dynamic characteristic's requirement, and the practicality is good, sees the following explanation in detail.

In order to achieve the above purpose, the utility model provides a following technical scheme:

the utility model provides a pair of parameter adjustable switching power supply feedback loop, including error amplifier U1, resistance R1, electric capacity C1 and electric capacity C2, resistance R1 and electric capacity C1 are established ties between error amplifier U1's reverse input and output, electric capacity C2 is parallelly connected with resistance R1 and electric capacity C1, parallelly connected regulating circuit on the electric capacity C2, the regulating circuit comprises MOS pipe Q1, resistance R3, electric capacity C3 series connection, MOS pipe Q1's switching receives singlechip drive control.

Has the advantages that: switching power supply feedback loop can be according to switching power supply's application environment independently adjust the loop parameter, increase and decrease zero point, the utmost point number in the feedback loop then to the realization lasts for switching power supply provides stable output in full input voltage scope and full load range, has also satisfied switching power supply high dynamic characteristic's requirement simultaneously, the practicality is good.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a circuit diagram of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described in detail below. It is to be understood that the embodiments described are only some embodiments of the invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention.

Referring to fig. 1, U1 is an operational amplifier, which collects a sampling value by using a negative feedback principle and compares the sampling value with a reference, thereby obtaining an error signal and comparing the error signal with a sawtooth wave to obtain a correct duty ratio to control a power switching tube, so that a power supply loop is stable.

The utility model provides a parameter adjustable switching power supply feedback loop, including error amplifier U1, resistance R1, electric capacity C1 and electric capacity C2, resistance R1 and electric capacity C1 are established ties between error amplifier U1's reverse input end and output, and electric capacity C2 is parallelly connected with resistance R1 and electric capacity C1; the capacitor C2 is also connected in parallel with an adjusting circuit, the adjusting circuit is composed of a MOS transistor Q1, a resistor R3 and a capacitor C3 connected in series, the switching of the MOS transistor Q1 is driven and controlled by a single chip, the MOS transistor Q1 is in a normally open state, that is, the adjusting circuit does not participate in a feedback loop of the switching power supply at ordinary times, because in general application, an error amplifier loop is composed of a resistor R1, a capacitor C1 and a capacitor C2, a negative feedback loop composed of a resistor R1, a capacitor C1 and a capacitor C2 is equivalent to inserting a zero and a pole to form a common type 2 amplifier, the open loop gain at low frequency is large to filter out low frequency ripples, the open loop gain at high frequency is reduced to prevent high frequency noise from oscillating in the loop, so that it can be ensured that the power supply passes through frequency, phase margin and gain margin meet design requirements, but the loop parameters of the type 2 amplifier are determined by three devices of a resistor R1, a capacitor C1 and, the flexibility is poor, and in some complex applications, the above-mentioned set of loop parameters cannot globally take care of each input voltage condition, each output load condition, each environmental condition, and cannot find a compromise loop parameter.

When the application environment of the switching power supply circuit changes and the original loop parameters cannot meet specific requirements (such as low output voltage requirement, large output load requirement and the like), the single chip can be controlled to close the MOS transistor Q1 (the MOS transistor Q1 is used for switching), the adjusting circuit is switched on, the resistor R3 and the capacitor C3 are connected in parallel to the capacitor C2, so that the number of zero points and poles in the feedback loop is increased, the original error amplifier circuit forms a higher-level error amplifying circuit, the defects of the feedback loop with characteristic conditions are compensated by higher design flexibility, the loop parameters can meet the requirements in the full-input voltage and full-load range, the switching power supply can be ensured to continuously provide stable output, meanwhile, the requirement of high dynamic characteristics of the switching power supply is met, and the practicability is good.

The above description is only for the specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto, and any person skilled in the art can easily think of the changes or substitutions within the technical scope of the present invention, and all should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.

Claims (1)

1. A parameter-adjustable switching power supply feedback loop comprises an error amplifier U1, a resistor R1, a capacitor C1 and a capacitor C2, wherein the resistor R1 and the capacitor C1 are connected in series between an inverted input end and an output end of the error amplifier U1, the capacitor C2 is connected in parallel with the resistor R1 and the capacitor C1, the parameter-adjustable switching power supply feedback loop is characterized in that the capacitor C2 is connected with an adjusting circuit in parallel, the adjusting circuit is formed by connecting an MOS tube Q1, the resistor R3 and the capacitor C3 in series, and the opening and closing of the MOS tube Q1 are driven and controlled by a single chip microcomputer.

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