Non-isolated BUCK positive and negative voltage on-off control circuit

Abstract

The utility model provides a non-isolated BUCK positive and negative voltage on-off control circuit. The non-isolated BUCK positive and negative voltage on-off control circuit comprises a power supply unit, a voltage dividing unit, a comparator U1, an optical coupler, a BUCK controller and a voltage output unit, the voltage dividing unit is connected to the two ends of the power supply unit, the output end of the voltage dividing unit is connected to the inverted input end of the comparator U1, and the in-phase input end of the comparator U1 is connected with reference voltage. The output end of the comparator U1 is connected to the input end of the optical coupler through the pull-up resistor, the output end of the optical coupler is connected to the input end of the BUCK controller, and the two output ends of the BUCK controller are connected to the two switching tubes in the voltage output unit respectively. The control circuit can be applied to a positive voltage output scene and a negative voltage output scene at the same time, startup and shutdown threshold value consistency and startup and shutdown control of any time sequence are achieved, therefore, standardized and serialized design of an electronic system is achieved, and the stability and reliability of the electronic system are improved.

Description

TECHNICAL FIELD

[0001] The utility model mainly relates to control circuit technical field, especially non-isolated BUCK positive and negative voltage switch control circuit. BACKGROUND

[0002] Non-isolated BUCK control circuit in switching power supply is widely used in military equipment, industrial control equipment, medical equipment and communication equipment field because of its high efficiency, small size and other advantages.The positive voltage output of control circuit is very widely used in product design, electronic circuit application, but many electric equipment will often use negative voltage power supply, such as serial port judgment level, operational amplifier power supply, IGBT drive, gallium nitride drive, sensor and other application scenarios.

[0003] There are three common methods of positive voltage input and negative voltage output: 1, using charge pump mode, but the load capacity is weak, the output power is extremely small, the voltage precision is low, and the application scene is limited. 2, Buck-Boost circuit, low efficiency, but the load capacity is weak, and the cost of this method is high. 3, isolated flyback circuit, which needs to use transformer isolation winding to output, so the design is more complex, the volume is large, and it is not suitable for small volume or high power density scene. And the general BUCK control circuit can realize negative voltage output, and the load capacity can reach dozens of amperes, and the input voltage range has covered several volts to hundreds of volts. The comprehensive cost, performance and volume are the highest in the negative voltage application scene.

[0004] In the prior art, although the same BUCK control circuit can realize positive voltage output and negative voltage output, because of the change of the reference ground of the BUCK control circuit, the switching threshold of the control circuit is inconsistent when the same BUCK control circuit outputs positive voltage and negative voltage. Figure 1 and Figure 2 As shown in the traditional BUCK control circuit, the switching machine is usually set by the voltage dividing resistor R1, R2 to divide the input voltage to set the switching threshold, and the BUCK controller EN is: , and the BUCK controller EN is: It can be seen that the switching voltage point is inconsistent when the same control circuit is used in positive voltage output and negative voltage output. INVENTION CONTENTS

[0005] The technical problem to be solved by the utility model is to provide a non-isolated BUCK positive and negative voltage switch control circuit (or called BUCK control circuit, converter, BUCK converter), which can be applied in positive voltage output and negative voltage output scene at the same time, realize consistent switching threshold and arbitrary timing switching control, so as to realize the standardization and serialization design of electronic system, and improve the stability and reliability of electronic system.

[0006] To solve the above technical problems, the utility model provides a kind of non-isolated BUCK positive and negative voltage switching machine control circuit, including power supply unit, voltage dividing unit, comparator U1, photo coupler, BUCK controller and voltage output unit;Wherein, the voltage dividing unit is connected at the both ends of the power supply unit, the output of the voltage dividing unit is connected to the inverting input of comparator U1, and the noninverting input of comparator U1 is connected to reference voltage;The output of the comparator U1 is connected to the input of the photo coupler by pull-up resistance, the output of the photo coupler is connected to the input of the BUCK controller, and the two outputs of the BUCK controller are respectively connected to the control end of two switching tubes in the voltage output unit;The voltage output unit includes positive voltage output and negative voltage output.

[0007] Optionally, the voltage dividing unit is a series branch composed of two resistors, and the two resistors are connected to the voltage output end.

[0008] Optionally, the two resistors in the series branch are variable resistors.

[0009] Optionally, the inverting input of the comparator U1 is also connected to an external timing control unit, and the external timing control unit is used to control the switching sequence and timing of the non-isolated BUCK positive and negative voltage switching machine control circuit.

[0010] Optionally, a diode D1 is connected in series between the comparator U1 and the pull-up resistance, the positive electrode of the diode D1 is connected to the output of the comparator U1, and the negative electrode of the diode D1 is connected to the pull-up resistance.

[0011] Compared with the prior art, the utility model has the following beneficial effects: the switching machine control of the converter is realized by the photo coupler opening or closing controlled by the comparator U1 after judgment, the problem of inconsistent control threshold of the converter caused by different positive and negative voltage reference grounds can be avoided by the BUCK controller controlled by the photo coupler, and the switching machine threshold consistency and arbitrary timing switching machine control can be realized in the positive voltage output and negative voltage output scenes, so as to realize the standardization and serialization design of electronic system, improve the stability and reliability of electronic system. BRIEF DESCRIPTION OF DRAWINGS

[0012] The accompanying drawings are included to provide a further understanding of the utility model, and they are incorporated and constitute a part of the utility model, the drawings show the embodiments of the utility model, and together with the specification, they play the role of explaining the principle of the utility model. In the drawings:

[0013] Figure 1 is the schematic diagram of the converter positive voltage output in the traditional switching machine control circuit;

[0014] Figure 2 is a schematic diagram of a transformer negative voltage output in a conventional switch control circuit;

[0015] Figure 3 is a schematic diagram of a non-isolated BUCK positive and negative voltage switch control circuit (positive voltage output) according to an embodiment of the present application;

[0016] Figure 4 is a schematic diagram of a non-isolated BUCK positive and negative voltage switch control circuit (negative voltage output) according to an embodiment of the present application. DETAILED DESCRIPTION

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some examples or embodiments of the present application, and for those skilled in the art, the present application can be applied to other similar scenarios without creative labor. Unless it is obvious from the language environment or otherwise stated, the same reference numbers in the drawings represent the same structure or operation.

[0018] It should be understood that when a component is referred to as being "on", "connected to", "coupled to", or "contacting" another component, it can be directly on, connected to, coupled to, or contacting the other component, or intervening components can be present. In contrast, when a component is referred to as being "directly on", "directly connected to", "directly coupled to", or "directly contacting" another component, there are no intervening components present. Similarly, when a first component is referred to as being "electrically in contact with" or "electrically coupled to" a second component, there is an electrical path between the first component and the second component that allows current to flow. The electrical path can include capacitors, coupled inductors, and / or other components that allow current to flow, even without direct contact between conductive components.

[0019] The embodiment provides a non-isolated BUCK positive and negative voltage switch control circuit, including a power supply unit, a voltage dividing unit, a comparator U1, an optical coupler, a BUCK controller and a voltage output unit, wherein the voltage dividing unit is connected between the power supply unit, the output end of the voltage dividing unit is connected to the inverting input end of the comparator U1, and the non-inverting input end of the comparator U1 is connected to a reference voltage; the output end of the comparator U1 is connected to the input end of the optical coupler through a pull-up resistor, the output end of the optical coupler is connected to the input end of the BUCK controller, and the two output ends of the BUCK controller are respectively connected to the control ends of two switching tubes in the voltage output unit; the voltage output unit includes a positive voltage output and a negative voltage output.

[0020] Furthermore, the voltage divider unit is a series branch consisting of two resistors, with the voltage output terminal located between the two resistors.

[0021] Furthermore, the two resistors in the series branch are variable resistors.

[0022] Furthermore, the inverting input of comparator U1 is also connected to an external timing control unit, which is used to control the power-on and power-off sequence and timing of the non-isolated BUCK positive and negative voltage power-on control circuit (converter).

[0023] Furthermore, a diode D1 is connected in series between the comparator U1 and the pull-up resistor. The positive terminal of the diode D1 is connected to the output terminal of the comparator U1, and the negative terminal of the diode D1 is connected to the pull-up resistor.

[0024] For example, refer to Figure 3 and Figure 4 As shown, in this embodiment, the converter's power-on / off is controlled by voltage divider resistors R3 and R4 to set the power-on / off threshold. Then, comparator U1 determines the threshold and controls the optocoupler to turn on or off, thus achieving power-on / off control of the converter. Here, REF is the comparator's reference voltage, VCC is the comparator's power supply, diode D1 prevents VCC voltage from flowing back to the comparator's output port, and R5 is the optocoupler's pull-up and current-limiting resistor. Controlling the BUCK controller via the optocoupler avoids the problem of inconsistent converter control thresholds caused by different positive and negative voltage reference grounds. Specifically, when applying a positive voltage output, the BUCK controller EN is: When using a negative pressure output application, the EN setting of the BUCK controller is: Therefore, the switching voltage point is the same when the same converter is used for both positive and negative voltage output.

[0025] Meanwhile, the external timing control port can flexibly control the power-on and power-off sequence and timing of the converter, including simultaneous activation of positive and negative voltages, activation of positive voltage first followed by negative voltage, activation of negative voltage first followed by positive voltage, and activation of positive and negative voltages with required delays.

[0026] This embodiment uses a non-isolated BUCK positive and negative voltage power-on / off control circuit. After determining the voltage level using comparator U1, it controls the optocoupler to turn on or off to achieve power-on / off control of the converter. By controlling the BUCK controller through the optocoupler, the problem of inconsistent converter control thresholds caused by different positive and negative voltage reference grounds can be avoided. Therefore, it can be applied to both positive and negative voltage output scenarios, achieving consistent power-on / off thresholds and arbitrary timing power-on / off control. This enables the standardization and serialization of electronic system design, improving the stability and reliability of the electronic system.

[0027] For those skilled in the art, the above disclosure of the utility model is merely illustrative and does not constitute a limitation of the present utility model. Although not explicitly stated herein, those skilled in the art may make various modifications, improvements, and corrections to the present utility model. Such modifications, improvements, and corrections are suggested in the present utility model and therefore remain within the spirit and scope of the exemplary embodiments of the present utility model.

[0028] Although the present invention has been described with reference to specific embodiments, those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and various equivalent changes or substitutions can be made without departing from the spirit of the present invention. Therefore, any changes or modifications to the above embodiments within the scope of the essential spirit of the present invention will fall within the scope of the claims of the present invention.

Claims

1. A non-isolated BUCK positive and negative voltage switching control circuit, characterized in that, The non-isolated BUCK positive and negative voltage switching machine control circuit comprises a power supply unit, a voltage dividing unit, a comparator U1, an optical coupler, a BUCK controller and a voltage output unit; wherein the voltage dividing unit is connected across the power supply unit, the output end of the voltage dividing unit is connected to the inverting input end of the comparator U1, and the non-inverting input end of the comparator U1 is connected to a reference voltage; the output end of the comparator U1 is connected to the input end of the optical coupler through a pull-up resistor, the output end of the optical coupler is connected to the input end of the BUCK controller, and the two output ends of the BUCK controller are respectively connected to the control ends of two switching tubes in the voltage output unit; the voltage output unit comprises positive voltage output and negative voltage output.

2. The non-isolated BUCK positive and negative voltage switching control circuit according to claim 1, characterized in that, The voltage dividing unit is a series branch composed of two resistors, and the two resistors are connected to each other through a voltage output end.

3. The non-isolated BUCK positive and negative voltage switching control circuit according to claim 2, characterized in that, The two resistors in the series branch are variable resistors.

4. The non-isolated BUCK positive and negative voltage switching control circuit according to claim 1, characterized in that, The non-inverting input end of the comparator U1 is also connected to an external timing control unit, and the external timing control unit is used to control the switching sequence and timing of the non-isolated BUCK positive and negative voltage switching machine control circuit.

5. The non-isolated BUCK positive and negative voltage switching control circuit according to claim 1, characterized in that, A diode D1 is connected in series between the comparator U1 and the pull-up resistor, the anode of the diode D1 is connected to the output end of the comparator U1, and the cathode of the diode D1 is connected to the pull-up resistor.

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