Overvoltage protection circuit and electronic equipment

Abstract

The utility model relates to an overvoltage protection circuit and electronic equipment, the overvoltage protection circuit does not need to depend on an additional power supply for power supply, and an overvoltage trigger circuit is switched on based on the output voltage of a detected power supply circuit under the condition that the sampling voltage output by a voltage detection circuit reaches an overvoltage protection threshold value; an overvoltage protection signal is output to trigger the power supply circuit to implement overvoltage protection operation; moreover, the threshold adjusting circuit can continuously apply a compensation voltage to the voltage detection circuit based on the output voltage, and the compensation voltage is superposed on the sampling voltage, so that the output voltage of the power supply circuit for triggering the overvoltage protection operation next time is reduced, and certain safety requirements are met.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electronic circuits, and particularly relates to an overvoltage protection circuit and an electronic device. BACKGROUND

[0002] For a power adapter, when an open loop fault occurs, an overvoltage protection (OVP) of a power control chip is often triggered. A conventional overvoltage protection scheme often needs a stable external power supply to maintain a lock state. CONTENT OF THE UTILITY MODEL

[0003] The application aims to provide an overvoltage protection circuit and an electronic device, and aims to solve the problem that a conventional overvoltage protection scheme often needs a stable external power supply to maintain a lock state.

[0004] In a first aspect, an overvoltage protection circuit is provided, comprising:

[0005] a voltage detection circuit, configured to be connected to an output end of a power supply circuit, detect an output voltage of the power supply circuit, and output a sampling voltage;

[0006] an overvoltage trigger circuit, connected to the output end of the power supply circuit, the voltage detection circuit, and an overvoltage protection end of the power supply circuit, configured to be turned on when the output voltage of the voltage detection circuit reaches an overvoltage protection threshold value, output an overvoltage protection signal to the overvoltage protection end of the power supply circuit, and trigger the power supply circuit to implement an overvoltage protection operation;

[0007] a threshold value adjustment circuit, connected to the output end of the power supply circuit, the overvoltage trigger circuit, and the voltage detection circuit, configured to be turned on based on the turn-on of the overvoltage trigger circuit, and continuously apply a compensation voltage to the sampling voltage based on the output voltage to the voltage detection circuit.

[0008] In some embodiments, the voltage detection circuit comprises a voltage division network, the voltage division network is connected between the output end of the power supply circuit and a ground end, a voltage division output end of the voltage division network constitutes the output end of the voltage detection circuit, and the voltage division output end of the voltage division network is connected to the threshold value adjustment circuit and the overvoltage trigger circuit.

[0009] In some embodiments, the voltage detection circuit further comprises a filter device, the filter device is connected between the voltage division output end of the voltage division network and the ground end.

[0010] In some embodiments, the overvoltage trigger circuit comprises a voltage stabilization driving module, an overvoltage trigger module, and a switch module.

[0011] The voltage stabilizing driving module, the overvoltage triggering module and the switch module are connected in series between the output end of the power supply circuit and the ground end; the switch module is further connected with the overvoltage triggering circuit, and the switch module is used for being turned on when the output voltage of the voltage detection circuit reaches the overvoltage protection threshold; the voltage stabilizing driving module is connected with the threshold adjusting circuit, and is used for controlling the threshold adjusting circuit to be turned on when the switch module is turned on; the overvoltage triggering module is connected with the overvoltage protection end of the power supply circuit, and is used for outputting the overvoltage protection signal to the overvoltage protection end of the power supply circuit when the switch module is turned on.

[0012] In some embodiments, the voltage stabilizing driving module comprises a voltage stabilizing device, a first current limiter, a second current limiter and a first photoelectric coupler;

[0013] The input end of the voltage stabilizing device is connected with the output end of the power supply circuit, the voltage stabilizing device, the first current limiter and the second current limiter are connected in series, the light emitting source of the first photoelectric coupler is connected in parallel with the second current limiter, and the light receiver of the first photoelectric coupler is connected with the threshold adjusting circuit, and is used for controlling the turn-on and turn-off of the threshold adjusting circuit.

[0014] In some embodiments, the overvoltage triggering module comprises a third current limiter, a fourth current limiter and a second photoelectric coupler, the third current limiter and the fourth current limiter are connected in series between the voltage stabilizing driving module and the switch module, the light emitting source of the second photoelectric coupler is connected in parallel with the fourth current limiter, and the light receiver of the second photoelectric coupler constitutes the output end of the overvoltage triggering circuit and is connected with the overvoltage protection end of the power supply circuit.

[0015] In some embodiments, the switch module comprises a controllable precision voltage stabilizing source, the anode of the controllable precision voltage stabilizing source is connected with the ground, the cathode of the controllable precision voltage stabilizing source is connected with the overvoltage triggering module, and the reference electrode of the controllable precision voltage stabilizing source is connected with the output end of the voltage detection circuit.

[0016] In some embodiments, the threshold adjusting circuit comprises a first unidirectional conducting device, a first capacitor, a second capacitor, a fifth current limiter, a sixth current limiter and a second unidirectional conducting device;

[0017] The input end of the first unidirectional conducting device is connected with the output end of the power supply circuit, the output end of the first unidirectional conducting device is grounded through the first capacitor and is connected to the light receiver collector of the first optocoupler, the first end of the fifth current limiter is connected with the light receiver emitter, the second end of the fifth current limiter is grounded through the second capacitor and is connected with the input end of the second unidirectional conducting device, and the output end of the second unidirectional conducting device is connected to the voltage detection circuit through the sixth current limiter.

[0018] In some embodiments, the threshold adjusting circuit further comprises a third unidirectional conducting device, a first switch tube and a first voltage divider;

[0019] The input end of the third unidirectional conducting device is connected with the output end of the power supply circuit, the control end of the first switch tube is connected with the output end of the second unidirectional conducting device through the sixth current limiter, the output end of the third unidirectional conducting device is connected with the first conducting end of the first switch tube, and the second conducting end of the first switch tube is connected to the voltage detection circuit through the first voltage divider.

[0020] In a second aspect, the embodiments of the present application further provide an electronic device, which comprises:

[0021] A power supply circuit;

[0022] The overvoltage protection circuit as described above is connected with the output end and the overvoltage protection end of the power supply circuit.

[0023] In some embodiments, the output voltage of the power supply circuit before implementing the overvoltage protection operation is greater than the output voltage after implementing the overvoltage protection operation.

[0024] In some embodiments, the overvoltage protection circuit is further connected with the power supply end and / or the feedback end of the power supply circuit.

[0025] Compared with the related art, the embodiments of the present application have the following beneficial effects:

[0026] The overvoltage protection circuit provided by the embodiments of the present application does not need to rely on an additional power supply, the overvoltage triggering circuit is based on the output voltage of the detected power supply circuit, turns on in the case that the sampling voltage output by the voltage detection circuit reaches the overvoltage protection threshold value, and outputs an overvoltage protection signal to trigger the power supply circuit to implement the overvoltage protection operation, and the threshold adjusting circuit can continuously apply a compensation voltage to the sampling voltage output by the voltage detection circuit, so that the output voltage of the power supply circuit triggering the overvoltage protection operation next time is lower, meeting some regulatory requirements. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1A structure schematic diagram of an overvoltage protection circuit provided by an embodiment of the present application is shown in FIG. 1.

[0028] Figure 2 A structure schematic diagram of an overvoltage protection circuit provided by an embodiment of the present application is shown in FIG. 1.

[0029] Figure 3 An example circuit diagram of an overvoltage protection circuit provided by an embodiment of the present application is shown in FIG. 2.

[0030] Figure 4 An example circuit diagram of an overvoltage protection circuit provided by an embodiment of the present application is shown in FIG. 2.

[0031] Figure 5 A light load output waveform simulation diagram of a power supply circuit based on the overvoltage protection circuit in an example of the present application is shown in FIG. 3.

[0032] Figure 6 A full load output waveform simulation diagram of a power supply circuit based on the overvoltage protection circuit in an example of the present application is shown in FIG. 4. DETAILED DESCRIPTION

[0033] In order to make the technical problems solved by the present application, the technical solutions and the beneficial effects clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application.

[0034] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element.

[0035] It should be understood that the terms "length", "width", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0036] In addition, the terms "first", "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first", "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0037] For power adapter, the output is generally a touchable circuit, for example, according to some safety standards, it is divided into energy classification that needs to meet ES1 circuit, that is, the current or voltage level does not exceed a certain limit value under normal, abnormal, fault (non-safety protection) conditions.

[0038] When the open-loop fault occurs in the power supply system, the overvoltage protection of the power supply control chip is often triggered. For some power supply control chips with repeated start as overvoltage protection scheme, the output voltage will present repeated pulse form, and according to the safety standards, the output voltage at this time is regarded as alternating voltage, and the peak value thereof shall not exceed 42.4V.

[0039] Embodiments of the present application provide an overvoltage protection circuit which can be applied to the overvoltage protection process of the power supply control chip with repeated start as overvoltage protection scheme. For example, the first trigger voltage does not exceed 60V, and the subsequent repeated start voltage is not higher than 42.4V, so as to meet certain safety standards.

[0040] Please refer to Figure 1 An embodiment of the present application provides an overvoltage protection circuit including a voltage detection circuit 110, an overvoltage trigger circuit 120 and a threshold adjustment circuit 130.

[0041] The voltage detection circuit 110 is connected to the output end Vo of the power supply circuit 10, detects the output voltage Vout of the power supply circuit 10, and outputs a sampling voltage; the overvoltage trigger circuit 120 is connected to the output end Vo of the power supply circuit 10, the voltage detection circuit 110 and the overvoltage protection end OVP of the power supply circuit 10, and the overvoltage trigger circuit 120 is used to conduct in the case that the output voltage of the voltage detection circuit 110 reaches the overvoltage protection threshold value, output an overvoltage protection signal to the overvoltage protection end OVP of the power supply circuit 10, and trigger the power supply circuit 10 to implement overvoltage protection operation; the threshold adjustment circuit 130 is connected to the output end Vo of the power supply circuit 10 and the overvoltage trigger circuit 120, and is turned on based on the conduction of the overvoltage trigger circuit 120, so as to continuously apply a compensation voltage Vref to the sampling voltage based on the output voltage Vout to the voltage detection circuit 110.

[0042] It can be understood that the power supply circuit 10 includes a power supply control chip, the overvoltage protection end OVP of the power supply circuit 10 is the OVP pin of the power supply control chip, and the overvoltage protection operation of the power supply circuit 10 is, for example, that the power supply control chip stops the power supply circuit 10 output, or the power supply control chip restarts, etc.

[0043] Before the threshold adjustment circuit 130 is turned on, the output voltage of the voltage detection circuit 110 is the sampling voltage. After the threshold adjustment circuit 130 is turned on, the output voltage of the voltage detection circuit 110 includes the sampling voltage superimposed with the compensation voltage Vref. It can be understood that after the threshold adjustment circuit 130 is turned on, the sampling voltage needs a lower voltage value to reach the overvoltage protection threshold value, that is, the output voltage Vout of the power supply circuit 10 can be lower than the output voltage Vout of the first overvoltage protection triggered after the power supply circuit 10 is started, so as to trigger the overvoltage protection operation of the power supply circuit 10.

[0044] For example, the overvoltage protection circuit is configured for the power supply circuit 10, which is divided into three parts of voltage detection, trigger memory and overvoltage restart. The voltage detection is responsible for detecting the output voltage Vout of the power supply circuit 10. When the output voltage Vout exceeds the set first trigger value, an overvoltage protection signal is given to the power supply circuit 10 to restart the power supply circuit 10; and a signal is also given to the threshold adjustment circuit 130. At this time, the threshold adjustment circuit 130 will remember this trigger, and the set sampling voltage of the overvoltage protection signal output by the triggerable overvoltage trigger circuit 120 of the voltage detection circuit 110 is lowered.

[0045] In some embodiments, the voltage detection circuit 110 includes a voltage division network connected between the output end Vo of the power supply circuit 10 and the ground end. The voltage division output end of the voltage division network constitutes the output end of the voltage detection circuit 110, and the voltage division output end of the voltage division network is connected with the threshold adjustment circuit 130 and the overvoltage trigger circuit 120.

[0046] The threshold adjustment circuit 130 applies a compensation voltage Vref to the voltage division output end of the voltage division network. The compensation voltage Vref adds a reference voltage to the voltage detection circuit 110, so that the output voltage Vout of the second overvoltage protection triggered by the power supply circuit 10 is lowered, and the subsequent output voltage Vout will not exceed this voltage, thereby meeting some safety requirements.

[0047] Please refer to Figure 2In some embodiments, the overvoltage triggering circuit 120 comprises a voltage stabilizing driving module 121, an overvoltage triggering module 122, and a switch module 123; the voltage stabilizing driving module 121, the overvoltage triggering module 122, and the switch module 123 are connected in series between the output terminal Vo of the power supply circuit 10 and the ground terminal; the switch module 123 is further connected with the voltage detecting circuit 110, and the switch module 123 is used to be turned on when the output voltage of the voltage detecting circuit 110 reaches the overvoltage protection threshold value; the voltage stabilizing driving module 121 is connected with the threshold value adjusting circuit 130, and is used to control the threshold value adjusting circuit 130 to be turned on when the switch module 123 is turned on; the overvoltage triggering module 122 is connected with the overvoltage protection terminal OVP of the power supply circuit 10, and is used to output an overvoltage protection signal to the overvoltage protection terminal OVP of the power supply circuit 10 when the switch module 123 is turned on.

[0048] The voltage stabilizing driving module 121 supplies a stable voltage to the overvoltage triggering module 122, thereby protecting the overvoltage triggering module 122 and the subsequent circuit. The switch module 123 is actually used to control the turn-on and turn-off of the overvoltage triggering module 122.

[0049] Please refer to Figure 3 In some embodiments, the voltage dividing network comprises series-connected voltage dividing resistors R11 and R12, the voltage dividing resistors R11 and R12 are connected in series to form a voltage dividing network between the output terminal Vo of the power supply circuit 10 and the ground terminal, and the series connection node of the voltage dividing resistors R11 and R12 constitutes a voltage dividing output terminal of the voltage dividing network. It can be understood that the sampling voltage, i.e. the output voltage Vout, output by the voltage detecting circuit 110 is divided into voltage components in proportion to the voltage dividing ratio of the voltage dividing network.

[0050] In some embodiments, in some application scenarios, for example, in the application to a network port circuit, the voltage detecting circuit 110 further comprises a filter device C10 connected between the voltage dividing output terminal of the voltage dividing network and the ground terminal. The filter device C10 is used to suppress the network port surge, so as to avoid the mis-triggering of the overvoltage protection of the power supply circuit 10 caused by the reverse flow of the surge transient energy. The filter device C10 is, for example, a capacitor.

[0051] In some embodiments, the voltage stabilizing driving module 121 comprises a voltage stabilizing device ZD1, a first current limiter R1, a second current limiter R2, and a first optocoupler U1.

[0052] The input terminal of the voltage stabilizing device ZD1 is connected with the output terminal Vo of the power supply circuit 10, the voltage stabilizing device ZD1, the first current limiter R1, and the second current limiter R2 are connected in series, the light-emitting source of the first optocoupler U1 is connected in parallel with the second current limiter R2, and the light-receiving source of the first optocoupler U1 is connected with the threshold value adjusting circuit 130, thereby controlling the turn-on and turn-off of the threshold value adjusting circuit 130.

[0053] The voltage stabilizing device ZD1 is, for example, a voltage stabilizing diode, the cathode and the anode of which are respectively connected to the input and output of the voltage stabilizing device ZD1. The first current limiter R1 and the second current limiter R2 comprise a resistor or a circuit comprising a resistor and a capacitor. The driving of the threshold value adjusting circuit 130 adopts the first optoelectronic coupler U1 instead of a conventional triode device, which can reduce the error between the control and the output, increase the anti-interference ability, and provide control accuracy and reliability.

[0054] In some embodiments, the overvoltage triggering module 122 comprises a third current limiter R3 and a fourth current limiter R4 connected in series between the voltage stabilizing driving module 121 and the switching module 123, and a second optoelectronic coupler U2, the light-emitting source of which is connected in parallel with the fourth current limiter R4, and the light-receiving source of which constitutes the output of the overvoltage triggering circuit 120 and is connected to the overvoltage protection end OVP of the power supply circuit 10.

[0055] The third current limiter R3 and the fourth current limiter R4 comprise a resistor or a circuit comprising a resistor and a capacitor. The driving of the threshold value adjusting circuit 130 adopts the optoelectronic coupler instead of a conventional triode device, which can reduce the error between the control and the output, increase the anti-interference ability, and provide control accuracy and reliability. Figure 3 In the example shown, the overvoltage protection end comprises OVP+ and OVP-.

[0056] In some embodiments, the switching circuit comprises a controllable precision voltage stabilizing source D11, the anode of which is connected to the ground, the cathode of which is connected to the overvoltage triggering module 122, and the reference electrode of which is connected to the output of the voltage detecting circuit 110.

[0057] The first current limiter R1 and the third current limiter R3 are used to limit the transient current of the first optoelectronic coupler U1 and the controllable precision voltage stabilizing source D11, and to protect them. It is suggested that the resistance of the first current limiter R1 and the third current limiter R3 should not be too large, so as not to affect the output voltage Vout of the power supply circuit 10 in the second triggering.

[0058] In some embodiments, the threshold value adjusting circuit 130 comprises a first unidirectional conduction device D1, a first capacitor C1, a second capacitor C2, a fifth current limiter R5, a sixth current limiter R6, and a second unidirectional conduction device D2.

[0059] The input end of the first unidirectional conducting device D1 is connected to the output end Vo of the power supply circuit 10, the output end of the first unidirectional conducting device D1 is connected to the light receiver collector of the first optocoupler U1 through the first capacitor C1 and is grounded, the first end of the fifth current limiter R5 is connected to the light receiver emitter, the second end of the fifth current limiter R5 is grounded through the second capacitor C2 and is connected to the input end of the second unidirectional conducting device D2, the output end of the second unidirectional conducting device D2 is connected to the voltage detection circuit 110 through the sixth current limiter R6, and is specifically connected to the output end of the voltage detection circuit 110.

[0060] The first unidirectional conducting device D1 and the second unidirectional conducting device D2, for example, include diodes or semiconductor transistors. The fifth current limiter R5 and the sixth current limiter R6 include resistors or circuits including resistors and capacitors.

[0061] The first unidirectional conducting device D1 and the first capacitor C1 serve to keep the voltage of the light receiver collector of the first optocoupler U1 higher than the voltage of the emitter, and prevent the second capacitor C2 from being discharged reversely to the output end Vo of the power supply circuit 10 through the first optocoupler U1 when the output voltage Vout of the power supply circuit 10 is lower than the voltage across the second capacitor C2.

[0062] The fifth current limiter R5 serves to limit the charging current of the first optocoupler U1 to protect the first optocoupler U1. The second unidirectional conducting device D2 serves to prevent the output voltage Vout of the power supply circuit 10 from charging the second capacitor C2 through the sixth current limiter R6, thereby improving the stability of the system.

[0063] For example, when the output voltage Vout of the power supply circuit 10 reaches the trigger voltage corresponding to the set first overvoltage protection threshold value, the voltage across the voltage dividing resistor R12 reaches the reference voltage of the controllable precision voltage regulator D11 through voltage division, the controllable precision voltage regulator D11 is turned on, at this time, the output current of the power supply circuit 10 flows to the ground through the loop overvoltage trigger circuit 120, the light source of the second optocoupler U2 is thus turned on, the overvoltage protection ends OVP+ and OVP- connected across the light receiver of the second optocoupler U2 flow through the current to trigger the overvoltage protection of the power supply circuit 10. At the same time, the light receiver of the first optocoupler U1 is turned on, the output current of the power supply circuit 10 flows through the first unidirectional conducting device D1, the light receiver of the first optocoupler U1, the fifth current limiter R5, a part of the current charges the second capacitor C2, and the other part of the current flows through the second unidirectional conducting device D2 and the sixth current limiter R6 to charge the voltage dividing resistor R12, which is equivalent to applying a compensation voltage Vref to the voltage dividing resistor R12. The voltage across the second current limiter R2 is thus raised, thereby reducing the trigger voltage of the second overvoltage protection of the power supply circuit 10, and the subsequent output voltage Vout will not exceed this trigger voltage, thereby meeting the safety requirements. In addition, each overvoltage protection trigger charges the second capacitor C2, and when the power supply circuit 10 is turned off, the second capacitor C2 discharges through the sixth current limiter R6, and when the voltage of the second capacitor C2 drops to 0V, the output voltage Vout of the overvoltage protection of the power supply circuit 10 returns to the set first voltage value.

[0064] Please refer to Figure 4 In some embodiments, the threshold adjustment circuit 130 further comprises a third unidirectional conducting device D3, a first switch Q1 and a first voltage divider R7.

[0065] The input end of the third unidirectional conducting device D3 is connected to the output end Vo of the power supply circuit 10, the control end of the first switch Q1 is connected to the output end of the second unidirectional conducting device D2 through the sixth current limiter R6, the output end of the third unidirectional conducting device D3 is connected to the first conducting end of the first switch Q1, and the second conducting end of the first switch Q1 is connected to the voltage detection circuit through the first voltage divider R7, and specifically connected to the output end of the voltage detection circuit 110.

[0066] For example, the third unidirectional conducting device D3 includes a diode or a semiconductor transistor. The first voltage divider R7 includes a resistor. The first switch Q1 includes an N-channel MOS tube. The third unidirectional conducting device D3 functions to prevent the filter device C10 from discharging to the output end Vo of the power supply circuit 10 through the body diode of the first switch Q1; and the sixth current limiter R6 functions to limit the driving current of the first switch Q1.

[0067] In this embodiment, when the output voltage Vout of the power supply circuit 10 reaches the trigger voltage corresponding to the set first overvoltage protection threshold value, the overvoltage protection ends OVP+ and OVP- connected at both ends of the light receiver of the second optocoupler U2 flow through the current to trigger the overvoltage protection of the power supply circuit 10, the light receiver of the first optocoupler U1 is turned on, a part of the current flows through the second unidirectional conducting device D2 and the sixth current limiter R6 to drive the first switch tube Q1, the first switch tube Q1 is thus turned on, and the output voltage Vout of the power supply circuit 10 flows through the third unidirectional conducting device D3, the first switch tube Q1, the first voltage divider R7, and the voltage dividing resistor R12 to the ground, which is equivalent to connecting a first voltage divider R7 in parallel to the two ends of the upper voltage dividing resistor R11, reducing the resistance value R11 of the upper voltage dividing resistor (equivalent to applying a compensation voltage Vref to the voltage dividing resistor R12), thereby reducing the output voltage Vout triggering the second overvoltage protection of the power supply circuit 10, and the subsequent output voltage Vout will not exceed this trigger voltage, thereby meeting the safety requirements. Please continue to refer to Figures 1 to 4 In a second aspect, the embodiments of the present application also provide an electronic device, which comprises a power supply circuit 10 and an overvoltage protection circuit as above, the overvoltage protection circuit being connected with the output end Vo of the power supply circuit 10 and the overvoltage protection end OVP.

[0068] For example, the power supply circuit 10 comprises a power supply control chip, the overvoltage protection end OVP of the power supply circuit 10 is the OVP pin of the power supply control chip, and the power supply circuit 10 implements the overvoltage protection operation such as power supply control chip restart.

[0069] In some embodiments, the output voltage (for example, 60V) Vout of the power supply circuit 10 before implementing the overvoltage protection operation is greater than the output voltage (for example, 42.2V) Vout after implementing the overvoltage protection operation, thereby meeting the relevant safety standards.

[0070] In one example, the highest output voltage Vout triggering the first overvoltage protection is set to 61V, the highest output voltage Vout triggering the second overvoltage protection is set to 36V, and the output waveform under light load is as follows Figure 5 As shown in the figure, the output waveform under full load is as follows Figure 6 As shown in the figure.

[0071] As can be seen from the simulation results, the overvoltage protection scheme of the embodiments of the present application can trigger the overvoltage protection of the power supply control chip when the output voltage Vout reaches the set value triggering the first overvoltage protection, and the set value of the output voltage Vout triggering the second overvoltage protection will be reduced to below 42.4V, thereby meeting the safety requirements.

[0072] In addition, the overvoltage protection signals output by the overvoltage protection end OVP+ and OVP- of the primary side of the circuit can not only act on the OVP pin of the power control chip, but also can be connected with the feedback end of the power circuit 10 and act on the feedback pin of the power control chip. When the overvoltage protection is triggered for the first time, the overvoltage protection circuit can replace the original feedback loop, and then the output voltage Vout of the power circuit 10 is stabilized to trigger the overvoltage protection set value for the second time; or the overvoltage protection circuit can also be connected with the power supply end of the power circuit 10, that is, act on the power supply circuit of the power control chip. After the overvoltage protection is triggered for the first time, the power supply voltage of the power supply circuit is pulled down, so as to control the restart time of the power control chip.

[0073] Compared with the prior art, the output signal of the optoelectronic coupler is used as the overvoltage protection signal in the embodiment of the application, and the flexibility is higher, and the application is more scene-rich, which is not limited to only high-level or only low-level triggering. In addition, the device used in the embodiment of the application does not contain a triode as a switching device, and the stability is high and the consistency is good. The embodiment of the application does not need to rely on an additional power supply circuit, and the power supply circuit 10 has almost no loss when the overvoltage protection does not occur, so as to ensure that the system will not have additional efficiency loss.

[0074] The above-described embodiments are only used to illustrate the technical solutions of the application, rather than limit them; although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the application, and should be included in the protection scope of the application.

Claims

1. An overvoltage protection circuit, characterized by, The application relates to a voltage detection circuit, which comprises the following components: a voltage detection circuit connected to the output end of a power supply circuit, used for detecting the output voltage of the power supply circuit and outputting a sampling voltage; an overvoltage trigger circuit connected to the output end of the power supply circuit, the voltage detection circuit and the overvoltage protection end of the power supply circuit, used for turning on when the output voltage of the voltage detection circuit reaches an overvoltage protection threshold value, outputting an overvoltage protection signal to the overvoltage protection end of the power supply circuit and triggering the power supply circuit to implement overvoltage protection operation; a threshold value adjustment circuit connected to the output end of the power supply circuit, the overvoltage trigger circuit and the voltage detection circuit, used for turning on based on the turning on of the overvoltage trigger circuit and continuously applying a compensation voltage to the sampling voltage based on the output voltage to the voltage detection circuit.

2. The overvoltage protection circuit of claim 1, wherein, The voltage detection circuit comprises a voltage dividing network connected between the output end of the power supply circuit and a ground end, and the voltage dividing output end of the voltage dividing network constitutes the output end of the voltage detection circuit and is connected to the threshold value adjustment circuit and the overvoltage trigger circuit.

3. The overvoltage protection circuit of claim 2, wherein, The voltage detection circuit further comprises a filter device connected between the voltage dividing output end of the voltage dividing network and the ground end.

4. The overvoltage protection circuit of any one of claims 1 to 3, wherein, The overvoltage trigger circuit comprises a voltage stabilizing driving module, an overvoltage trigger module and a switch module. The voltage stabilizing driving module, the overvoltage trigger module and the switch module are connected in series between the output end of the power supply circuit and the ground end; the switch module is further connected to the voltage detection circuit and is used for turning on when the output voltage of the voltage detection circuit reaches the overvoltage protection threshold value; the voltage stabilizing driving module is connected to the threshold value adjustment circuit and is used for controlling the turning on of the threshold value adjustment circuit when the switch module turns on; the overvoltage trigger module is connected to the overvoltage protection end of the power supply circuit and is used for outputting the overvoltage protection signal to the overvoltage protection end of the power supply circuit when the switch module turns on.

5. The overvoltage protection circuit of claim 4, wherein, The voltage stabilizing driving module comprises a voltage stabilizing device, a first current limiter, a second current limiter and a first photoelectric coupler; the input end of the voltage stabilizing device is connected to the output end of the power supply circuit, the voltage stabilizing device, the first current limiter and the second current limiter are connected in series, the light emitting source of the first photoelectric coupler is connected in parallel to the second current limiter, and the light receiver of the first photoelectric coupler is connected to the threshold value adjustment circuit and is used for controlling the turning on and turning off of the threshold value adjustment circuit.

6. The overvoltage protection circuit of claim 4, wherein, The overvoltage trigger module comprises a third current limiter, a fourth current limiter and a second photoelectric coupler, the third current limiter and the fourth current limiter are connected in series between the voltage stabilizing driving module and the switch module, the light emitting source of the second photoelectric coupler is connected in parallel to the fourth current limiter, and the light receiver of the second photoelectric coupler constitutes the output end of the overvoltage trigger circuit and is connected to the overvoltage protection end of the power supply circuit.

7. The overvoltage protection circuit of claim 4, wherein, The switch module comprises a controllable precision voltage source, an anode of the controllable precision voltage source being grounded, a cathode of the controllable precision voltage source being connected to the overvoltage trigger module, and a reference pole of the controllable precision voltage source being connected to an output end of the voltage detection circuit.

8. The overvoltage protection circuit of claim 5, wherein, The threshold adjusting circuit comprises a first unidirectional conducting device, a first capacitor, a second capacitor, a fifth current limiter, a sixth current limiter, and a second unidirectional conducting device. An input end of the first unidirectional conducting device is connected to an output end of the power supply circuit, an output end of the first unidirectional conducting device is grounded through the first capacitor and connected to a light receiver collector of the first optocoupler, a first end of the fifth current limiter is connected to a light emitter stage of the light receiver, a second end of the fifth current limiter is grounded through the second capacitor and connected to an input end of the second unidirectional conducting device, and an output end of the second unidirectional conducting device is connected to the voltage detection circuit through the sixth current limiter.

9. The overvoltage protection circuit of claim 8, wherein, The threshold adjusting circuit further comprises a third unidirectional conducting device, a first switch tube, and a first voltage divider. An input end of the third unidirectional conducting device is connected to an output end of the power supply circuit, a control end of the first switch tube is connected to an output end of the second unidirectional conducting device through the sixth current limiter, an output end of the third unidirectional conducting device is connected to a first conducting end of the first switch tube, and a second conducting end of the first switch tube is connected to the voltage detection circuit through the first voltage divider.

10. An electronic device, comprising: The electronic device comprises: a power supply circuit; The overvoltage protection circuit according to any one of claims 1 to 9 is connected to an output end, an overvoltage protection end of the power supply circuit.

11. The electronic device of claim 10, wherein, The output voltage of the power supply circuit before implementing the overvoltage protection operation is greater than the output voltage after implementing the overvoltage protection operation.

12. The electronic device of claim 10, wherein, The overvoltage protection circuit is further connected to a power supply end and / or a feedback end of the power supply circuit.

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