Summary of the invention
Embodiment of the present invention technical problem to be solved there are provided a kind of wider in output voltage excursionIn the case of the relatively stable and dead-beat negative-feedback circuit of output voltage.
A kind of negative-feedback circuit provided by the present invention, controls including the first operational amplifier, the second operational amplifier and PWMDevice processed, the inverting input of described first operational amplifier connects output voltage V-OUT, described first computing by the with resistanceThe in-phase input end of amplifier connects reference voltage V-SET, the anti-phase input of described first operational amplifier by the second resistanceHold the node between the first resistance to pass sequentially through the 3rd resistance and the first electric capacity be connected to the outfan of the first operational amplifier,Node between described first electric capacity and the outfan of the first operational amplifier is connected to the first resistance and by the second electric capacityNode between three resistance, the node between outfan and first electric capacity of described first operational amplifier is by the 4th resistance evenBeing connected to the normal phase input end of the second operational amplifier, the inverting input of described second operational amplifier is connected by the 5th resistanceThe current sampling signal of transformer primary side, the outfan of described second operational amplifier is connected to the second computing by the 7th resistanceThe inverting input of amplifier, the node between described 7th resistance and the outfan of the second operational amplifier passes through the 9th resistanceBeing connected with the agitator timing resistor pin of PWM controller, the outfan of described second operational amplifier is also by the 8th resistanceIt is connected with the error amplifier homophase input pin of PWM controller.
Wherein, the inverting input of described operational amplifier D2 connects with reference to d. c. voltage signal also by the 6th resistance.
In negative-feedback circuit of the present invention, the outfan of described second operational amplifier is connected to by the 8th resistanceThe error amplifier in-phase input end EA+ of PWM controller, the control wide to carry out PWM tune.Meanwhile, described second operation amplifierThe outfan of device is also by the agitator timing resistor pin RT of the 9th resistance Yu PWM controller, to carry out the control of frequency modulation.OnStating negative-feedback circuit can make output voltage when excursion is wider, and output voltage is relatively stable and dead-beat.
Detailed description of the invention
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, completeDescribe, it is clear that described embodiment is only a part of embodiment of the present invention rather than whole embodiments wholely.Based onEmbodiment in the present invention, it is every other that those of ordinary skill in the art are obtained under not making creative work premiseEmbodiment, broadly falls into the scope of protection of the invention.
First, before embodiment is described, it is necessary to some herein presented terms are explained.ExampleAs:
If occurring herein using the term such as " first ", " second " to describe various element, but these elements should notLimited by these terms.These terms are only used for distinguishing an element and another element.Therefore, " first " element can alsoIt is referred to as " second " element without departing from the teachings of the present invention.
In addition, it is to be understood that when mentioning that an element " connects " or during " coupled " to another element, it can be directGround connects or is directly coupled to another element or can also there is intermediary element.On the contrary, when mentioning an element " directlyConnect " or " directly couple " to another element time, the most there is not intermediary element.
The various terms occurred in this article are used only for describing the purpose of specific embodiment and being not intended as thisThe restriction of invention.Unless context clearly dictates otherwise, then singulative is intended to also include plural form.
When using term " to include " in this manual and/or time " including ", these terms specify described feature, wholeThe existence of body, step, operation, element and/or parts, but be also not excluded for more than one other feature, entirety, step, operation,The existence of element, parts and/or its group and/or additional.
About embodiment:
Refer to the circuit diagram that Fig. 1, Fig. 1 are the better embodiment of negative-feedback circuit of the present invention, described negative-feedback circuitBetter embodiment include operational amplifier D1, D2 and PWM controller D3, the inverting input of described operational amplifier D1 lead toCrossing resistance R1 and connect output voltage V-OUT, the in-phase input end of described operational amplifier D1 connects reference voltage by resistance R2V-SET。
Node between inverting input and the resistance R1 of described operational amplifier D1 passes sequentially through resistance R3 and electric capacity C1Being connected to the outfan of operational amplifier D1, the node between described electric capacity C1 and the outfan of operational amplifier D1 passes through electric capacityC2 is connected to the node between resistance R1 and R3.
Node between outfan and the electric capacity C1 of described operational amplifier D1 is connected to operational amplifier by resistance R4The normal phase input end of D2.The inverting input of the described operational amplifier D2 current sample by the former limit of resistance R5 connection transformerSignal IP1, connects with reference to d. c. voltage signal VREF also by resistance R6.The outfan of described operational amplifier D2 passes through resistanceR7 is connected to the inverting input of operational amplifier D2.Node between described resistance R7 and the outfan of operational amplifier D2 leads toCrossing resistance R9 to be connected with the agitator timing resistor pin RT of PWM controller D3, the outfan of described operational amplifier D2 is the most logicalCross resistance R8 to be connected with the error amplifier in-phase input end EA+ of PWM controller D3.In other embodiments, if operation amplifierDevice D2 precision is higher, also can omit resistance R6 and with reference to d. c. voltage signal.
In present embodiment, the outfan of described operational amplifier D2 is connected to the mistake of PWM controller D3 by resistance R8Difference amplifier in-phase input end EA+, the control wide to carry out PWM tune.Meanwhile, the outfan of described operational amplifier D2 also byResistance R9 and the agitator timing resistor pin RT of PWM controller D3, to carry out the control of frequency modulation.Negative feedback of the present inventionCircuit can make output voltage when excursion is wider, and output voltage is relatively stable and dead-beat.
These are only embodiments of the present invention, not thereby limit the scope of the claims of the present invention, every utilize the present inventionEquivalent structure or equivalence flow process that description and accompanying drawing content are made convert, or are directly or indirectly used in other relevant technologyField, is the most in like manner included in the scope of patent protection of the present invention.