阅读说明：本技术 开关电源控制电路及控制方法 (Switching power supply control circuit and control method ) 是由 何勇吉 窦训金 周逊伟 于 2019-08-22 设计创作，主要内容包括：本发明提出一种开关电源控制电路及控制方法,所述开关电源包括上管和下管,所述开关电源控制电路包括升压电路,所述升压电路输入端连接开关电源输入端,所述升压电路输出第一电压,控制所述升压电路工作用以驱动所述上管导通。本发明开关电源控制电路采用升压电路为上管提供驱动电源,无需设置bootstrap引脚和自举电容。(The invention provides a switching power supply control circuit and a control method, wherein the switching power supply comprises an upper tube and a lower tube, the switching power supply control circuit comprises a booster circuit, the input end of the booster circuit is connected with the input end of the switching power supply, the booster circuit outputs a first voltage, and the booster circuit is controlled to work to drive the upper tube to be conducted. The switch power supply control circuit adopts the booster circuit to provide a driving power supply for the upper tube, and does not need to be provided with a bootstrap pin and a bootstrap capacitor.)

1. the utility model provides a switching power supply control circuit, switching power supply includes top tube and low tube, its characterized in that: the switching power supply control circuit comprises a boosting circuit, the input end of the boosting circuit is connected with the input end of the switching power supply, the boosting circuit outputs a first voltage to control the boosting circuit to work so as to drive the upper pipe to be conducted.

2. the switching power supply control circuit according to claim 1, wherein: the switching power supply control circuit further comprises an auxiliary circuit, the auxiliary circuit receives the first voltage, the output end of the auxiliary circuit is connected with the upper tube control end, and the auxiliary circuit is used for controlling the upper tube to be turned off.

3. The switching power supply control circuit according to claim 2, wherein: the boost circuit receives a first control signal, the auxiliary circuit receives a second control signal, the first control signal is used for controlling the boost circuit to work, and the second control signal is used for controlling the auxiliary circuit to switch off the upper tube.

4. The switching power supply control circuit according to claim 3, wherein: the boost circuit comprises a first inductor, a first switch tube, a rectifier tube and a first capacitor, wherein a first end of the first inductor is connected with an input end of a switching power supply, a second end of the first inductor is connected with a first end of the first switch tube, a second end of the first switch tube is grounded, and a control end of the first switch tube receives a first control signal; the utility model discloses a switch power supply, including rectifier tube, first inductance, first switch tube, first electric capacity, top tube second end, top tube first end is switching power supply input or output, the first electric capacity upper voltage does first voltage is connected to rectifier tube first end, rectifier tube second end connection first inductance and the first common terminal of first switch tube, first electric capacity second end connection top tube second end, top tube first end is switching power supply input or output.

5. The switching power supply control circuit according to claim 4, wherein: the boost circuit further comprises a clamping circuit, and the clamping circuit is connected with the first capacitor in parallel.

6. the switching power supply control circuit according to claim 3, wherein: the auxiliary circuit comprises a second switch tube, the first end of the second switch tube is connected with the upper tube control end, the second end of the second switch tube is connected with the first end of the first capacitor, and the control end of the second switch tube is connected with the input end of the switching power supply.

7. The switching power supply control circuit according to claim 6, wherein: the auxiliary circuit further comprises a third switch tube, the first end of the third switch tube is connected with the upper tube control end, the second end of the third switch tube is grounded, and the third switch tube control end receives the second control signal.

8. The switching power supply control circuit according to any one of claims 1 to 7, wherein: the switching power supply is a voltage boosting circuit or a voltage reducing circuit.

9. The switching power supply control circuit according to claim 4, wherein: the switching power supply control circuit is integrated in a chip, and a lead wire inductor of the chip is used as the first inductor.

10. A switching power supply control method is provided, wherein the switching power supply comprises an upper tube and a lower tube, and the switching power supply control method is characterized in that: the input end of a booster circuit is connected with the input end of a switching power supply, the booster circuit outputs a first voltage and controls the booster circuit to work so as to drive the upper tube to be conducted; receiving the first voltage by using an auxiliary circuit, wherein the output end of the auxiliary circuit is connected with the upper tube control end, and the auxiliary circuit is used for controlling the upper tube to be turned off.

Technical Field

The invention relates to the field of power electronics, in particular to a switching power supply control circuit and a control method.

Background

In the prior art, fig. 1 illustrates a schematic diagram of a control circuit of a buck circuit, fig. 2 illustrates a schematic diagram of a control circuit of a boost circuit, in order to drive an upper tube Q1 of the boost circuit or the buck circuit, a bootstrap capacitor Cbs needs to be provided, a first end of the bootstrap capacitor Cbs is connected to a common terminal SW of an upper tube Q1 and a lower tube Q2, and a second end of the bootstrap capacitor Cbs is connected to an input end of the boost circuit or the buck circuit through a diode. In the prior art, a bootstrap capacitor Cbs and a bootstrap pin BST need to be arranged, and the bootstrap capacitor Cbs is large and not easy to integrate in a chip, thereby increasing the area and the design cost of the circuit.

Disclosure of Invention

The invention aims to provide a switching power supply control circuit with a small area and a control method, which are used for solving the problem that a bootstrap capacitor needs to be arranged in the prior art.

In order to achieve the above object, the present invention provides a switching power supply control circuit, where the switching power supply includes an upper tube and a lower tube, the switching power supply control circuit includes a voltage boost circuit, an input end of the voltage boost circuit is connected to an input end of the switching power supply, and the voltage boost circuit outputs a first voltage to control the voltage boost circuit to be turned on to drive the upper tube to be turned on.

Optionally, the switching power supply control circuit further includes an auxiliary circuit, the auxiliary circuit receives the first voltage, an output end of the auxiliary circuit is connected to the upper tube control end, and the auxiliary circuit is used for controlling the upper tube to be turned off.

optionally, the boost circuit receives a first control signal, the auxiliary circuit receives a second control signal, the first control signal is used to control the boost circuit to operate, and the second control signal is used to control the auxiliary circuit to turn off the upper tube.

Optionally, the boost circuit includes a first inductor, a first switching tube, a rectifier tube and a first capacitor, a first end of the first inductor is connected to the input end of the switching power supply, a second end of the first inductor is connected to the first end of the first switching tube, a second end of the first switching tube is grounded, and a control end of the first switching tube receives the first control signal; the utility model discloses a switch power supply, including rectifier tube, first inductance, first switch tube, first electric capacity, top tube second end, top tube first end is switching power supply input or output, the first electric capacity upper voltage does first voltage is connected to rectifier tube first end, rectifier tube second end connection first inductance and the first common terminal of first switch tube, first electric capacity second end connection top tube second end, top tube first end is switching power supply input or output.

Optionally, the boost circuit further includes a clamping circuit, and the clamping circuit is connected in parallel with the first capacitor.

Optionally, the auxiliary circuit includes a second switch tube, a first end of the second switch tube is connected to the upper tube control end, a second end of the second switch tube is connected to the first end of the first capacitor, and the second switch tube control end is connected to the switching power supply input end.

Optionally, the auxiliary circuit further includes a third switch tube, a first end of the third switch tube is connected to the upper tube control end, a second end of the third switch tube is grounded, and the third switch tube control end receives the second control signal.

Optionally, the switching power supply is a voltage boosting circuit or a voltage reducing circuit.

Optionally, the switching power supply control circuit is integrated in a chip, and a lead inductance of the chip is used as the first inductance.

The invention also provides a control method of the switching power supply, the switching power supply comprises an upper tube and a lower tube, the input end of the boosted circuit is connected with the input end of the switching power supply, the boosted circuit outputs a first voltage and controls the working of the boosted circuit to drive the upper tube to be conducted; receiving the first voltage by using an auxiliary circuit, wherein the output end of the auxiliary circuit is connected with the upper tube control end, and the auxiliary circuit is used for controlling the upper tube to be turned off.

Compared with the prior art, the invention has the following advantages: the input end of a booster circuit is connected with the input end of a switching power supply, the booster circuit outputs a first voltage and controls the booster circuit to work so as to drive the upper tube to be conducted; receiving the first voltage by using an auxiliary circuit, wherein the output end of the auxiliary circuit is connected with the upper tube control end, and the auxiliary circuit is used for controlling the upper tube to be turned off. The switch power supply control circuit adopts the booster circuit to provide a driving power supply for the upper tube, and a bootstrap (bootstrap) pin and a bootstrap capacitor are not required to be arranged.

Drawings

FIG. 1 is a control schematic of a prior art voltage reduction circuit;

FIG. 2 is a control schematic of a prior art boost circuit;

FIG. 3 is a control block diagram of the voltage step-down circuit of the present invention;

FIG. 4 is a control block diagram of the boost circuit of the present invention;

FIG. 5 is a schematic diagram of a control circuit of the voltage step-down circuit of the present invention;

FIG. 6 is a schematic diagram of a control circuit of the boost circuit of the present invention;

FIG. 7 is a working wave diagram of the present invention;

Detailed Description

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to only these embodiments. The invention is intended to cover alternatives, modifications, equivalents and alternatives which may be included within the spirit and scope of the invention.

In the following description of the preferred embodiments of the present invention, specific details are set forth in order to provide a thorough understanding of the present invention, and it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.

the invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the drawings are in simplified form and are not to precise scale for the purpose of facilitating and clearly explaining the embodiments of the present invention.

As shown in fig. 3, a control block diagram of the step-down circuit of the present invention is illustrated, where the step-down circuit includes an upper tube Q1, a lower tube Q2, an inductor L1, and a capacitor C2, the upper tube Q1 is a main switching tube, and the lower tube Q2 is a rectifying tube. The upper tube Q1 has a first end receiving the input voltage VIN, a second end connected to the first end of the lower tube Q2, and a second end of the lower tube Q2 connected to ground. The common terminal SW of the upper tube Q1 and the lower tube Q2 is connected with the first terminal of an inductor L1, the second terminal of the inductor L1 is connected with the first terminal of a capacitor C1, and the second terminal of the capacitor C1 is grounded. The buck circuit control circuit includes a boost circuit for providing drive to the upper transistor Q1, and utilizes the parasitic line inductance and the bond wire inductance of the pin when the control circuit is integrated as the boost circuit storage inductor, i.e., inductor L2 in the figure. The voltage reduction circuit control circuit further comprises a pulse generation circuit, and the pulse generation circuit outputs a plurality of pulse signals which are respectively used for driving the boosting circuit in the control circuit and controlling the working state of the lower tube Q2.

as shown in fig. 4, a control block diagram of the boost circuit of the present invention is illustrated, where the boost circuit includes an upper tube Q1, a lower tube Q2, an inductor L1, and a capacitor C2, the upper tube Q1 is a synchronous rectification switch tube, and the lower tube Q2 is a main switch tube. The first end of the upper tube Q1 is connected with the first end of the capacitor C2 as the output end, the second end of the capacitor C2 is grounded, the second end of the upper tube Q1 is connected with the first end of the lower tube Q2, and the second end of the lower tube Q2 is grounded. The common terminal SW of the upper tube Q1 and the lower tube Q2 is connected to a first terminal of an inductor L1, and a second terminal of the inductor L1 is connected to receive an input voltage VIN. The boost circuit control circuit also includes a boost circuit for providing drive to the upper transistor Q1, and utilizes the parasitic inductance of the circuit and the pin of the control circuit when integrated as the energy storage inductance of the boost circuit, i.e., the inductance L2 in the figure. The boost circuit control circuit further comprises a pulse generating circuit which outputs a plurality of pulse signals for driving the boost circuit in the control circuit and controlling the working state of the lower tube Q2, respectively.

As shown in fig. 5, a schematic diagram of a control circuit of the step-down circuit of the present invention is illustrated, the control circuit includes a boost circuit, an auxiliary circuit and a pulse generating circuit, the boost circuit includes a first switch tube Q3, a first inductor L2, a first capacitor C3, a diode D1 and a first voltage regulator tube D2, the auxiliary circuit includes a second switch tube Q4 and a third switch tube Q5, the diode D1 is used as a rectifying tube of the boost circuit, and the first voltage regulator tube D2 is used as an output voltage of the boost clamp circuit. A first end of the first inductor L2 is connected to an input end of the step-down circuit, a second end of the first inductor L2 is connected to a first end of a first switch Q3, a second end of the first switch Q3 is grounded, and a control end of the first switch Q3 receives a first control signal pulse 1; the anode of the diode D1 is connected to the common terminal of the first inductor L2 and the first switch tube Q3, the cathode of the diode D1 is connected to the first terminal of the first capacitor C3, the second terminal of the first capacitor C3 is connected to the second terminal of the upper tube Q1, and the first terminal of the upper tube Q1 is the input terminal of the step-down circuit; the first voltage regulator tube D2 is connected with a first capacitor C3 in parallel, the first end of the second switch tube Q4 is connected with the control end of an upper tube Q1, the second end of the second switch tube Q4 is connected with the common end of a diode D1 and the first capacitor C3, and the control end of the second switch tube Q4 is connected with the input end of the voltage reduction circuit; the first end of the third switch Q5 is connected to the control end of the upper transistor Q1, the second end of the third switch Q5 is grounded, and the control end of the third switch Q5 receives a second control signal pulse 2. The pulse generating circuit generates a first control signal pulse1, a second control signal pulse2 and a control signal for driving the state of the lower tube switch. The working process of the voltage reduction circuit control circuit is as follows:

L1 inductive energy storage stage: a control end of the first switch tube Q3 applies a first control signal, when the first switch tube Q3 is conducted, the inductor L2 stores energy, and meanwhile, the conducting resistor of the first switch tube Q3 plays a role in limiting current; when the first switch tube Q3 is turned off, the current of the first inductor L2 charges the capacitor C3 through the diode D1, so that the voltage of the cathode of the first voltage regulator tube D2 rises, when the voltage of the first capacitor is higher than a first threshold VOUT + VTH (VTH is the gate threshold voltage of Q4), the second switch tube Q4 is turned on, the capacitor voltage of the first capacitor C3 is applied to the gate source of the upper tube Q1, and the upper tube Q1 is turned on.

L1 inductive power release stage: the control terminal of the third switching tube Q5 is applied with a second control signal, when the third switching tube Q5 is turned on, the gate of the upper tube Q1 is discharged to turn off the upper tube Q1, and then the pulse generating circuit outputs a pulse signal to drive the Q2 to be turned on for freewheeling.

As shown in fig. 6, a schematic diagram of a control circuit of the boost circuit of the present invention is illustrated, which is different from the buck control circuit of fig. 5 in that: the control end of a second switching tube Q4 is connected with the output end of the booster circuit; the working engineering is as follows:

l1 energy storage stage: the control end of the third switching tube Q5 applies a second control signal, the third switching tube Q5 is turned on to discharge to the gate of the lower tube Q2, so that the lower tube Q2 is turned off, then the pulse generating circuit outputs a pulse signal to drive the upper tube Q1 to be turned on, and the inductor L1 stores energy.

L1 energy release phase: the upper tube Q1 is off and inductor L1 current freewheels through the lower tube Q2 body diode. A control end of the first switch tube Q3 applies a first control signal, when the first switch tube Q3 is turned on, the first inductor L2 stores energy, and a turn-on Resistor (RDSON) of the first switch tube Q3 plays a role in current limiting; when the first switch tube Q3 is turned off, the current of the first inductor L2 charges the first capacitor C3 through the diode D1, so that the voltage of the cathode of the first regulator tube D2 rises, when the voltage of the first capacitor is higher than a first threshold VOUT + VTH (VTH is the gate threshold voltage of Q4), the second switch tube Q4 is turned on, the capacitor voltage of the first capacitor C3 is added to the gate source of the lower tube Q2, and the lower tube Q2 is turned on to play a role in synchronous rectification.

Fig. 7 illustrates a working wave diagram of the present invention, in which waveforms Q1-GS represent the on-off state of the upper tube Q1, waveforms Q2-GS represent the on-off state of the lower tube Q2, waveforms Q3-GS represent the on-off state of the first switching tube Q3, waveforms Q5-GS represent the on-off state of the third switching tube Q5, when the first switching tube Q3 is turned on for a short time, the lower tube Q2 is controlled to be turned off, and the upper tube Q1 is turned on; when the third switching tube Q5 is turned on briefly, the upper tube Q1 is controlled to be turned on, and the lower tube Q2 is controlled to be turned off.

Although the embodiments have been described and illustrated separately, it will be apparent to those skilled in the art that some common techniques may be substituted and integrated between the embodiments, and reference may be made to one of the embodiments not explicitly described, or to another embodiment described.

The above-described embodiments do not limit the scope of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the above-described embodiments should be included in the protection scope of the technical solution.