CN210693791U

CN210693791U - Switching power supply circuit, semiconductor chip and power supply device

Info

Publication number: CN210693791U
Application number: CN201921070762.3U
Authority: CN
Inventors: 刘苏; 王志勇; 孙慧慧; 俞建悦; 顾永德
Original assignee: Moso Power Supply Technology Co ltd
Current assignee: Moso Power Supply Technology Co ltd
Priority date: 2019-07-10
Filing date: 2019-07-10
Publication date: 2020-06-05
Anticipated expiration: 2029-07-10

Abstract

The embodiment of the utility model discloses switching power supply circuit, semiconductor chip and power supply unit, include: the device comprises an overcurrent protection circuit, an electromagnetic interference (EMI) filter circuit, an input rectification filter circuit, a main conversion circuit, a voltage feedback circuit, a Pulse Width Modulation (PWM) control circuit and a secondary synchronous rectification circuit; the main conversion circuit comprises the first MOS tube and a flyback transformer; the secondary synchronous rectification circuit comprises a second MOS tube. Through implementing the embodiment of the utility model provides a, can improve switching power supply's efficiency, reduce the loss of diode in the circuit, reduce cost and improve switching power supply circuit's security.

Description

Switching power supply circuit, semiconductor chip and power supply device

Technical Field

The present disclosure relates to power supply technologies, and particularly to a switching power supply circuit, a semiconductor chip and a power supply device.

Background

A Switch Mode Power Supply (SMPS), also called a switching Mode Power Supply or a switching converter, is a Power Supply. The input of the switching power supply is mostly an ac power supply (e.g., commercial power) or a dc power supply, and the output is mostly equipment requiring the dc power supply, such as a personal computer, and the switching power supply is used for converting voltage and current between the two.

Currently, the switching power supply of 12V5A generally uses two schottky diodes and a heat dissipation device to realize its function. However, the switching power supply adopting the circuit design is generally low in efficiency, and the loss of the diode in the circuit is high. Meanwhile, the heat dissipation device is large, so that the labor cost is increased, and in the manual processing process, the problems of element damage, electric corrosion of a contact, oxidation and the like caused by errors can be caused, even the contact resistance is increased, and various potential safety hazards are left.

SUMMERY OF THE UTILITY MODEL

An embodiment of the utility model provides a switching power supply circuit, semiconductor chip and power supply unit aims at improving switching power supply's efficiency, reduces the loss of diode in the circuit, reduce cost and improve circuit's security.

In a first aspect, an embodiment of the present invention provides a switching power supply circuit, which may include: the device comprises an overcurrent protection circuit, an electromagnetic interference (EMI) filter circuit, an input rectification filter circuit, a main conversion circuit, a voltage feedback circuit, a Pulse Width Modulation (PWM) control circuit and a secondary synchronous rectification circuit; the main conversion circuit comprises the first MOS tube and a flyback transformer; the secondary synchronous rectification circuit comprises a second MOS tube; the input end of the over-current protection circuit is connected with alternating current, and the over-current protection circuit is used for powering off the switching power supply circuit when the current input into the switching power supply circuit exceeds rated current; the input end of the EMI filter circuit is connected with the output end of the overcurrent protection circuit and is used for filtering interference signals of the switching power supply circuit; the input end of the input rectifying filter circuit is connected with the output end of the EMI filter circuit and is used for outputting a first direct current voltage; the primary side of the main conversion circuit is connected with the output end of the input rectification filter circuit and is used for transmitting the first direct current voltage to the secondary side of the main conversion circuit through the flyback transformer; the input end of the secondary synchronous rectification circuit is connected with the secondary side of the main conversion circuit and used for performing rectification filtering through the second MOS tube in the secondary synchronous rectification circuit and outputting a second direct-current voltage; the input end of the voltage feedback circuit is connected with the output end of the secondary synchronous rectification circuit and is used for feeding back the second direct-current voltage to the PWM control circuit; the input end of the PWM control circuit is connected with the output end of the voltage feedback circuit, and is also connected with the primary side of the main conversion circuit, and the PWM control circuit is used for stabilizing the second direct current voltage by adjusting the duty ratio of the first MOS tube in the main conversion circuit.

For switching power supply circuit among the prior art, the embodiment of the utility model provides a switching power supply circuit in flyback topology, secondary synchronous rectifier tube is chooseed for use and is replaced schottky diode to accomplish corresponding circuit function to realize reducing diode loss and raise the efficiency. The embodiment of the utility model provides an avoid using great heat dissipation device, reduced manufacturing cost and follow-up trouble's emergence probability, improved the security of circuit.

In a possible implementation manner, the main conversion circuit further includes a resistor-capacitor diode RCD absorption circuit, and the input rectification filter circuit includes a first capacitor and a second capacitor; the RCD absorption circuit is used for absorbing spike voltage in the turn-off process of the first MOS tube and reflected voltage of the secondary coil on the secondary side, and discharging the spike voltage and the reflected voltage to the first capacitor and the second capacitor.

In a possible implementation manner, when the first MOS transistor is turned on, the flyback transformer stores energy to drive the second MOS transistor to be turned off; when the first MOS tube is turned off, the flyback transformer releases the stored energy to the secondary side through coupling, and drives the second MOS tube to be conducted.

In one possible implementation, the EMI filter circuit includes a differential mode filter capacitor and a common mode filter inductor; the differential mode filter capacitor is in cross connection with a zero line and a live line and is used for eliminating differential mode interference; the common-mode filter inductor is connected in the EMI filter circuit in series and used for suppressing common-mode interference of the alternating current and preventing the switching power supply circuit from interfering with the alternating current.

In one possible implementation, the input rectifying and filtering circuit further includes a rectifying bridge;

the input rectifying and filtering circuit is specifically configured to: and full-wave rectification is carried out through the rectifier bridge, and the first direct-current voltage is output through filtering of the first capacitor and the second capacitor.

In one possible implementation, the PWM control circuit includes a PWM control chip IC; the voltage feedback circuit is specifically configured to: and feeding back the second direct current voltage to a feedback FB pin of the PWM control IC.

In a possible implementation manner, the PWM control circuit is specifically configured to modulate a gate bias of the first MOS transistor according to the second direct-current voltage, and adjust a duty ratio of the first MOS transistor, so as to implement stable voltage output of the switching power supply circuit.

In a possible implementation manner, the main conversion circuit further includes an auxiliary winding on the primary side; and the auxiliary winding is connected with the PWM control circuit and used for supplying power to the PWM control IC.

In a second aspect, embodiments of the present invention provide a semiconductor chip, which may include the switching power supply circuit described in the first aspect.

In a third aspect, the present invention further provides a power supply apparatus, which may include the switching power supply circuit described in the first aspect and the optional embodiments thereof or the chip described in the second aspect, and the apparatus can achieve the beneficial effects of the switching power supply circuit described in the first aspect and the optional embodiments thereof. The apparatus comprises a memory for storing a computer program, which may comprise program instructions, and a processor for controlling and managing the actions of the apparatus in accordance with the program instructions. Optionally, the power supply device may further include a transceiver for supporting communication of the device with other communication devices.

Drawings

The drawings to be used in the embodiments of the present invention will be described below.

Fig. 1 is a schematic diagram of an operating principle of a switching power supply circuit according to an embodiment of the present invention;

fig. 2 is a schematic circuit diagram of a switching power supply circuit according to an embodiment of the present invention.

Detailed Description

An embodiment of the utility model provides a switching power supply circuit, include: the switch power supply circuit improves the efficiency of the switch power supply and reduces the loss of diodes in the circuit.

The terms "comprising" and "having," and any variations thereof, as appearing in the specification, claims and drawings of the present application, are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those steps or elements listed, but may alternatively include other steps or elements not listed, or inherent to such process, method, article, or apparatus. Furthermore, the terms "first," "second," and "third," etc. are used to distinguish between different objects and are not used to describe a particular order.

In order to make the technical solution of the present invention better understood, the technical solution of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts shall belong to the protection scope of the present invention.

The following is a detailed description with reference to the drawings.

Referring to fig. 1, fig. 1 is a schematic diagram illustrating an operating principle of a switching power supply circuit according to an embodiment of the present invention, and as can be seen from fig. 1, the switching power supply circuit 100 includes: an overcurrent protection circuit 1001, an EMI filter circuit 1002, an input rectification filter circuit 1003, a main conversion circuit 1004, a voltage feedback circuit 1005, a PWM control circuit 1006 and a secondary synchronous rectification circuit 1007. As shown in fig. 1, an alternating current (i.e., AC) is input to the switching power supply circuit 100, passes through an overcurrent protection circuit 1001, an EMI filter circuit 1002, an input rectification filter circuit 1003, a flyback transformer, and a secondary synchronous rectification circuit 1007, and then outputs a dc voltage meeting the requirements to a load; the voltage feedback circuit 1005 obtains a dc voltage output to the load, and feeds the dc voltage back to the PWM control circuit 1006, and the PWM control circuit 1006 adjusts the on-time of the first MOS according to the dc voltage to stabilize the voltage. The RCD absorption circuit is used for absorbing leakage inductance energy, such as the superposition of a peak voltage and a reflection voltage caused by the leakage inductance energy. Optionally, the PWM control IC in the PWM control circuit is powered through an auxiliary winding of the flyback transformer. The embodiment of the utility model provides a do not do the restriction to the concrete connection mode between each module or the circuit in the switch power supply circuit.

The following is a detailed description of the structure and function of the switching power supply circuit 100 according to an embodiment of the present invention, please refer to fig. 2, fig. 2 is a schematic circuit diagram of the switching power supply circuit according to an embodiment of the present invention, and the embodiment of the present invention does not limit the specific circuit content when the same or similar circuit function is implemented.

As shown in fig. 2, the switching power supply circuit 100 may include: an overcurrent protection circuit 1001, an EMI filter circuit 1002, an input rectification filter circuit 1003, a main conversion circuit 1004, a voltage feedback circuit 1005, a PWM control circuit 1006 and a secondary synchronous rectification circuit 1007; the main conversion circuit 1004 comprises the first MOS transistor and a flyback transformer; the secondary synchronous rectification circuit 1007 comprises a second MOS transistor; the input end of the over-current protection circuit 1001 is connected with alternating current, and the over-current protection circuit 1001 is used for powering off the switching power supply circuit when the current input into the switching power supply circuit exceeds rated current; the input end of the EMI filter circuit 1002 is connected to the output end of the overcurrent protection circuit 1001, and is configured to filter an interference signal of the switching power supply circuit; the input end of the input rectifying filter circuit 1003 is connected with the output end of the EMI filter circuit 1002, and is configured to output a first direct-current voltage; the primary side of the main conversion circuit 1004 is connected to the output end of the input rectification filter circuit 1003, and is configured to transmit the first dc voltage to the secondary side of the main conversion circuit 1004 through the flyback transformer; the input end of the secondary synchronous rectification circuit 1007 is connected to the secondary side of the main conversion circuit 1004, and is configured to perform rectification filtering through the second MOS transistor in the secondary synchronous rectification circuit 1007 to output a second dc voltage; the input end of the voltage feedback circuit 1005 is connected to the output end of the secondary synchronous rectification circuit 1007, and is configured to feed back the second direct-current voltage to the PWM control circuit 1006; the input end of the PWM control circuit 1006 is connected to the output end of the voltage feedback circuit 1005, and is further connected to the primary side of the main converting circuit 1004, so as to stabilize the second dc voltage by adjusting the duty ratio of the first MOS transistor in the main converting circuit 1004.

In a possible implementation manner, the main converting circuit 1004 further includes a resistor-capacitor diode RCD absorption circuit, and the input rectifying and filtering circuit 1003 includes a first capacitor and a second capacitor; the RCD absorption circuit is used for absorbing spike voltage in the turn-off process of the first MOS tube and reflected voltage of the secondary coil on the secondary side, and discharging the spike voltage and the reflected voltage to the first capacitor and the second capacitor. The first capacitor and the second capacitor are bulk capacitors. Because the working process of the transformer (namely, the flyback transformer) is to store energy and then release the energy, rather than only playing a role of transferring the energy, the transformer is essentially a coupling inductor, and the coupling inductor is used for transferring the energy, thereby not only realizing the isolation of input and output, but also realizing the conversion of voltage, rather than only regulating the voltage by duty ratio. Since this coupling inductance (i.e., the flyback transformer) is not an ideal device, there is a leakage inductance, and there is also a stray inductance in the actual line. When the MOS transistor is turned off, the energy in the leakage inductance and the stray inductance may generate a high voltage spike at the drain of the MOS transistor, which may cause damage to the device. Therefore, the leakage inductance energy is processed by the RCD absorption circuit, and is temporarily stored by C (namely a capacitor) and dissipated by R (namely a resistor).

In a possible implementation manner, when the first MOS transistor is turned on, the flyback transformer stores energy to drive the second MOS transistor to be turned off; when the first MOS tube is turned off, the flyback transformer releases the stored energy to the secondary side through coupling, and drives the second MOS tube to be conducted. When the first MOS tube is conducted, the primary current of the transformer rises linearly under the action of the input voltage. The primary voltage of the transformer is sensed to the secondary side, and the second MOS tube is cut off reversely. When the first MOS tube is turned off, the primary current of the transformer is forced to be turned off, and then the primary inductor generates an induced electromotive force on the primary side in the MOS turning-off process. The induced electromotive force is coupled to the secondary through a winding of the transformer according to the law of electromagnetic induction, and the induced electromotive force of the secondary is positive up and negative down since the dotted terminal of the secondary and the primary are opposite. When the secondary induced electromotive force reaches the output voltage, the second MOS tube is conducted. The energy stored in the primary inductor when the MOS is switched on is coupled to the secondary inductor through the magnetic core and then released into the secondary output capacitor through the secondary coil. During the transfer of energy into the output capacitor, the secondary voltage is clamped to the output voltage because the secondary output capacitor has a large capacitance and the voltage is substantially constant. When the first MOS is turned on again, the next cycle starts.

In one possible implementation, the EMI filter circuit 1002 includes a differential mode filter capacitor and a common mode filter inductor; the differential mode filter capacitor is in cross connection with a zero line and a live line and is used for eliminating differential mode interference; the common mode filter inductor is connected in series in the EMI filter circuit 1002, and is used for suppressing the common mode interference of the alternating current and preventing the switching power supply circuit 100 from interfering with the alternating current. The EMI filter circuit of the input part is mainly used for absorbing instantaneous high-voltage pulse interference signals and guaranteeing normal operation of the circuit.

In one possible implementation, the input rectifying and filtering circuit 1003 further includes a rectifying bridge; the input rectifying and filtering circuit 1003 is specifically configured to: and full-wave rectification is carried out through the rectifier bridge, and the first direct-current voltage is output through filtering of the first capacitor and the second capacitor. The input rectifying and filtering circuit consists of a BD rectifying bridge and a Bulk capacitor, and converts input alternating current into direct current through full-wave rectification and filtering.

In one possible implementation, the PWM control circuit 1006 includes a PWM control chip IC; the voltage feedback circuit 1005 is specifically configured to: and feeding back the second direct current voltage to a feedback FB pin of the PWM control IC. The PWM control circuit is mainly used for adjusting the conduction time of the MOS tube according to the received feedback voltage so as to achieve the effect of adjusting or stabilizing the output voltage.

In a possible implementation manner, the PWM control circuit 1006 is specifically configured to change the on-time of the second MOS transistor by modulating the gate bias of the first MOS transistor according to the second direct-current voltage, so as to adjust the duty ratio of the first MOS transistor, and implement stable voltage output of the switching power supply circuit 100.

In one possible implementation, the main conversion circuit 1004 further includes an auxiliary winding on the primary side; the auxiliary winding is connected to the PWM control circuit 1006 for supplying power to the PWM control IC. And the power is supplied to the PWM control chip through an auxiliary winding on the primary side of the transformer (namely, an auxiliary winding in the primary coil) through a power supply pin connected with the PWM control chip.

It can be understood that the switching power supply circuit provided by the embodiment of the present invention can be applied to a chip with a driving function, and can also be applied to a device or an electronic product with a driving function; the embodiment of the utility model provides a switching power supply circuit can also use in power adapter, provides the voltage that accords with corresponding equipment requirement for terminal equipment such as personal notebook computer, desktop computer, cell-phone. The embodiment of the utility model provides an application to this circuit does not limit.

In another embodiment of the present invention, a semiconductor chip is further provided, and the semiconductor chip may be a chip of the switching power supply circuit described in the first aspect, or a chip integrating the switching power supply circuit described in the first aspect and other external circuits.

The above-mentioned embodiments further describe in detail the purpose, technical solution and beneficial effects of the embodiments of the present invention, and it should be understood that the above description is only a detailed description of the embodiments of the present invention, and is not used to limit the protection scope of the embodiments of the present invention, and any modification, equivalent replacement, improvement, etc. made on the basis of the technical solution of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

In the several embodiments provided in the present disclosure, it should be understood that the disclosed method can be implemented in other manners. For example, the above-described embodiments are merely illustrative, and the division into circuits and modules is merely a logical division, and other divisions may be realized in practice, for example, a plurality of units, circuits, modules or components may be combined or integrated into another system, or some features may be omitted or not executed.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention.

Claims

1. A switching power supply circuit, comprising: the device comprises an overcurrent protection circuit, an electromagnetic interference (EMI) filter circuit, an input rectification filter circuit, a main conversion circuit, a voltage feedback circuit, a Pulse Width Modulation (PWM) control circuit and a secondary synchronous rectification circuit; the main conversion circuit comprises a first MOS tube and a flyback transformer; the secondary synchronous rectification circuit comprises a second MOS tube; wherein the content of the first and second substances,

the input end of the over-current protection circuit is connected with alternating current, and the over-current protection circuit is used for powering off the switching power supply circuit when the current input into the switching power supply circuit exceeds rated current;

the input end of the EMI filter circuit is connected with the output end of the overcurrent protection circuit and is used for filtering interference signals of the switching power supply circuit;

the input end of the input rectifying filter circuit is connected with the output end of the EMI filter circuit and is used for outputting a first direct current voltage;

the primary side of the main conversion circuit is connected with the output end of the input rectification filter circuit and is used for transmitting the first direct current voltage to the secondary side of the main conversion circuit through the flyback transformer;

the input end of the secondary synchronous rectification circuit is connected with the secondary side of the main conversion circuit and used for performing rectification filtering through the second MOS tube in the secondary synchronous rectification circuit and outputting a second direct-current voltage;

the input end of the voltage feedback circuit is connected with the output end of the secondary synchronous rectification circuit and is used for feeding back the second direct-current voltage to the PWM control circuit;

the input end of the PWM control circuit is connected with the output end of the voltage feedback circuit, and is also connected with the primary side of the main conversion circuit, and the PWM control circuit is used for stabilizing the second direct current voltage by adjusting the duty ratio of the first MOS tube in the main conversion circuit.

2. The circuit of claim 1, wherein the main conversion circuit further comprises a resistor-capacitor diode (RCD) snubber circuit, and the input rectifying and filtering circuit comprises a first capacitor and a second capacitor;

the RCD absorption circuit is used for absorbing spike voltage in the turn-off process of the first MOS tube and reflected voltage of the secondary coil on the secondary side, and discharging the spike voltage and the reflected voltage to the first capacitor and the second capacitor.

3. The circuit of claim 2, wherein when the first MOS transistor is turned on, the flyback transformer stores energy to drive the second MOS transistor to turn off; when the first MOS tube is turned off, the flyback transformer releases the stored energy to the secondary side through coupling, and drives the second MOS tube to be conducted.

4. The circuit of claim 1, wherein the EMI filter circuit comprises a differential mode filter capacitor and a common mode filter inductor; the differential mode filter capacitor is in cross connection with a zero line and a live line and is used for eliminating differential mode interference; the common-mode filter inductor is connected in the EMI filter circuit in series and used for suppressing common-mode interference of the alternating current and preventing the switching power supply circuit from interfering with the alternating current.

5. The circuit of claim 2, wherein the input rectifying and filtering circuit further comprises a rectifying bridge;

6. The circuit of claim 1, wherein the PWM control circuit comprises a PWM control chip IC; the voltage feedback circuit is specifically configured to: and feeding back the second direct current voltage to a feedback FB pin of the PWM control IC.

7. The circuit according to claim 6, wherein the PWM control circuit is specifically configured to adjust a duty ratio of the first MOS transistor by modulating a gate bias of the first MOS transistor according to the second direct-current voltage, so as to achieve stable voltage output of the switching power supply circuit.

8. The circuit of claim 6, wherein the primary conversion circuit further comprises an auxiliary winding on the primary side; and the auxiliary winding is connected with the PWM control circuit and used for supplying power to the PWM control IC.

9. A semiconductor chip comprising the switching power supply circuit according to any one of claims 1 to 8.

10. A power supply device comprising the switching power supply circuit according to any one of claims 1 to 8 or the semiconductor chip according to claim 9.