CN112350279B - Power protection circuit and electronic device - Google Patents

Power protection circuit and electronic device Download PDF

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Publication number
CN112350279B
CN112350279B CN202011211372.0A CN202011211372A CN112350279B CN 112350279 B CN112350279 B CN 112350279B CN 202011211372 A CN202011211372 A CN 202011211372A CN 112350279 B CN112350279 B CN 112350279B
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Prior art keywords
resistor
electrically connected
voltage
control unit
capacitor
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CN112350279A (en
Inventor
高宽志
李有贵
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Hisense Visual Technology Co Ltd
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Hisense Visual Technology Co Ltd
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Priority to CN202010910236 priority
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    • HELECTRICITY
    • H02GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02HEMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/10Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
    • H02H7/12Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers

Abstract

The embodiment of the application provides a power protection circuit and electronic equipment. Therefore, when load impact occurs on the auxiliary circuit output, the power supply protection circuit and the electronic equipment comprising the power supply protection circuit can improve the voltage output by the main circuit or the power supply voltage of the control unit in the switching power supply, and then the large voltage can trigger the Over Voltage Protection (OVP) function of the switching power supply, so that the switching power supply stops working or restarts, the problem of overhigh temperature rise of a power panel device caused by the fact that the load on the auxiliary circuit output is increased is solved, and the safety performance of the switching power supply is improved.

Description

Power protection circuit and electronic device
Technical Field
The application relates to the technical field of power supplies, in particular to a power supply protection circuit and electronic equipment.
Background
The switching power supply has multiple outputs, which are generally divided into a main output and a sub-output. Where the primary output is often used to provide power to a primary function of the electronic device and the secondary output is used to provide power to a secondary function of the electronic device. For example, the main output is used to power a video signal in a television set and the secondary output is used to power an audio signal in a television set. As another example, the main output is used to power control circuitry in the printer and the sub output is used to power an ink jet motor in the printer.
Currently, when a load impact occurs at a secondary output, if a power supply power of the secondary output is designed according to the maximum load impact, a design cost increases, resulting in a non-competitive product. If the power supply power output by the auxiliary circuit is designed according to continuous load impact, continuous large current easily causes the temperature of a power supply board device to continuously rise to cause temperature rise out of control, and even potential safety hazards appear.
Disclosure of Invention
The application provides a power protection circuit and electronic equipment can solve the problem that the load grow leads to the temperature rise of power strip device too high on the auxiliary road output, has improved switching power supply's security performance.
In a first aspect, the present application provides a power protection circuit, comprising: the device comprises a control unit, a first transformer, a feedback circuit and a first detection circuit.
The first transformer is provided with a primary winding, an auxiliary winding and a secondary winding, the primary winding is used for inputting a first voltage, a first end of the secondary winding is used for outputting a second voltage to a first load, a second end of the secondary winding is used for outputting a third voltage to a second load, the auxiliary winding is used for outputting a fourth voltage to the control unit, the auxiliary winding is tightly coupled with a winding generating the second voltage in the secondary winding, the primary winding is used for being electrically connected with the first end of the control unit, the first end and the second end of the secondary winding are both used for being electrically connected with a feedback circuit, the feedback circuit is further electrically connected with the second end of the control unit, the auxiliary winding is used for being electrically connected with a first detection circuit, and the first detection circuit is further electrically connected with a third end of the control unit.
And the feedback circuit is used for controlling the second voltage to become larger when the second load becomes larger and sending a first signal to the control unit, wherein the first signal is used for indicating that the second voltage becomes larger. And the control unit is used for controlling the fourth voltage to be increased when the first signal is received. The first detection circuit is used for outputting a second signal to the control unit, and the second signal is related to the fourth voltage. And the control unit is also used for controlling the control unit to restart or stop working when the second signal is received or the voltage value of the second signal rises to a first preset threshold value.
In one possible design, the first detection circuit includes: the circuit comprises a first diode, a second diode, a first resistor, a first capacitor and a second capacitor.
The negative electrode of the first diode and the first end of the first capacitor are electrically connected with the third end of the control unit, the positive electrode of the first diode is electrically connected with the first level, the first end of the second capacitor and the negative electrode of the second diode respectively, the positive electrode of the second diode is electrically connected with the first end of the first resistor, the second end of the first resistor is electrically connected with the auxiliary winding, and the second end of the first capacitor and the second end of the second capacitor are grounded.
In one possible design, the feedback circuit is further configured to generate the first signal based on a feedback amount of the second voltage.
In one possible design, the feedback circuit includes: the third optical coupler, the thirteenth resistor, the fourteenth resistor, the third zener diode, the fifth capacitor, the fifteenth resistor, the sixteenth resistor, the seventeenth resistor, the eighteenth resistor, the first triode, the nineteenth resistor, the second triode, the twentieth resistor, the sixth capacitor, the seventh capacitor, the twenty-first resistor and the third diode.
Wherein, the fourth end of the third optical coupler is electrically connected with the second end of the control unit, the third end of the third optical coupler is grounded, the first end of the third optical coupler is respectively and electrically connected with the first end of the thirteenth resistor and the first end of the fourteenth resistor, the second end of the fourteenth resistor is electrically connected with the second end of the third optical coupler, the first end of the fifth capacitor and the first end of the third zener diode, the second end of the fifth capacitor is electrically connected with the first end of the fifteenth resistor, the second end of the fifteenth resistor is respectively and electrically connected with the first end of the seventeenth resistor, the first end of the eighteenth resistor and the second end of the third zener diode, the second end of the seventeenth resistor is respectively and electrically connected with the first end of the sixteenth resistor and the collector electrode of the first triode, the base electrode of the first triode is respectively and electrically connected with the collector electrode of the second triode, the first end of the twentieth resistor and the first end of the seventh capacitor, an emitting electrode of the second triode is electrically connected with a first end of a nineteenth resistor and a first end of a sixth capacitor respectively, a base electrode of the second triode is electrically connected with a second end of the sixth capacitor and a first end of a twenty-first resistor respectively, a second end of the twenty-first resistor is electrically connected with an anode of a third diode, a third end of the third voltage stabilizing diode, a second end of the eighteenth resistor, an emitting electrode of the first triode, a second end of the twentieth resistor and a second end of the seventh capacitor are grounded, a second end of the thirteenth resistor, a second end of the sixteenth resistor and a second end of the nineteenth resistor are electrically connected with a first end of the secondary winding, and a cathode of the third diode is electrically connected with a second end of the secondary winding.
In one possible design, the feedback circuit is further configured to generate the first signal based on a feedback amount of the second voltage and a feedback amount of the third voltage.
In one possible design, the feedback circuit includes: the circuit comprises a second optical coupler, a seventh resistor, an eighth resistor, a second voltage stabilizing diode, a fourth capacitor, a ninth resistor, a tenth resistor, an eleventh resistor and a twelfth resistor.
Wherein, the fourth end of the second optical coupler is electrically connected with the second end of the control unit, the third end of the second optical coupler is grounded, the first end of the second optical coupler is respectively and electrically connected with the first end of the seventh resistor and the first end of the eighth resistor, the second end of the eighth resistor is respectively and electrically connected with the second end of the second optical coupler, the first end of the fourth capacitor and the first end of the second voltage stabilizing diode, the second end of the fourth capacitor is electrically connected with the first end of the ninth resistor, the second end of the ninth resistor is respectively and electrically connected with the second end of the second voltage stabilizing diode, the first end of the tenth resistor, the first end of the eleventh resistor and the first end of the twelfth resistor are electrically connected, the third end of the second zener diode tube and the second end of the eleventh resistor are both grounded, the second end of the seventh resistor and the second end of the tenth resistor are both electrically connected with the first end of the secondary winding, and the second end of the twelfth resistor is electrically connected with the second end of the secondary winding.
In a second aspect, the present application provides a power protection circuit, comprising: the control unit, second transformer, feedback circuit and second detection circuitry.
The second transformer is provided with a primary winding and a secondary winding, the primary winding is used for inputting a first voltage, a first end of the secondary winding is used for outputting a second voltage to the first load, a second end of the secondary winding is used for outputting a third voltage to the second load, the primary winding is used for being electrically connected with a first end of the control unit, the first end and the second end of the secondary winding are both used for being electrically connected with the feedback circuit, the feedback circuit is further electrically connected with a second end of the control unit, the first end of the secondary winding is electrically connected with the second detection circuit, and the second detection circuit is electrically connected with a third end of the control unit.
And the feedback circuit is used for controlling the second voltage to become larger when the second load becomes larger and sending a first signal to the control unit, wherein the first signal is used for indicating that the second voltage becomes larger. And the control unit is used for controlling the second voltage to be increased when receiving the first signal. And a second detection circuit for outputting a third signal to the control unit, the third signal being related to the second voltage. And the control unit is also used for controlling the control unit to restart or stop working when the third signal is received or the voltage value of the third signal is increased to a second preset threshold value.
In one possible design, the second detection circuit includes: the circuit comprises a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, an NMOS transistor, a first optical coupler, a first voltage stabilizing diode and a third capacitor.
Wherein, the drain of the NMOS transistor is electrically connected with the third end of the control unit, the source of the NMOS transistor is grounded with the first end of the second resistor, the grid of the NMOS transistor is electrically connected with the second end of the second resistor and the third end of the first optical coupler respectively, the fourth end of the first optical coupler is electrically connected with the first end of the third resistor, the second end of the third resistor is electrically connected with the second level, the first end of the first optical coupler is electrically connected with the first end of the fourth resistor, the second end of the first optical coupler is electrically connected with the first end of the first voltage stabilizing diode, the second end of the first voltage stabilizing diode is electrically connected with the first end of the third capacitor, the first end of the fifth resistor and the first end of the sixth resistor respectively, the third end of the first voltage stabilizing diode, the second end of the third capacitor and the second end of the sixth resistor are both grounded, and the second end of the fourth resistor and the second end of the fifth resistor are both electrically connected with the first end of the secondary winding.
In one possible design, the feedback circuit is further configured to generate the first signal based on a feedback amount of the second voltage.
In one possible design, the feedback circuit includes: the circuit comprises a third optical coupler, a thirteenth resistor, a fourteenth resistor, a third voltage-stabilizing diode, a fifth capacitor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a first triode, a nineteenth resistor, a second triode, a twentieth resistor, a sixth capacitor, a seventh capacitor, a twenty-first resistor and a third diode.
Wherein, the fourth end of the third optical coupler is electrically connected with the second end of the control unit, the third end of the third optical coupler is grounded, the first end of the third optical coupler is respectively and electrically connected with the first end of the thirteenth resistor and the first end of the fourteenth resistor, the second end of the fourteenth resistor is electrically connected with the second end of the third optical coupler, the first end of the fifth capacitor and the first end of the third zener diode, the second end of the fifth capacitor is electrically connected with the first end of the fifteenth resistor, the second end of the fifteenth resistor is respectively and electrically connected with the first end of the seventeenth resistor, the first end of the eighteenth resistor and the second end of the third zener diode, the second end of the seventeenth resistor is respectively and electrically connected with the first end of the sixteenth resistor and the collector electrode of the first triode, the base electrode of the first triode is respectively and electrically connected with the collector electrode of the second triode, the first end of the twentieth resistor and the first end of the seventh capacitor, an emitting electrode of the second triode is electrically connected with a first end of the nineteenth resistor and a first end of the sixth capacitor respectively, a base electrode of the second triode is electrically connected with a second end of the sixth capacitor and a first end of the twenty-first resistor respectively, a second end of the twenty-first resistor is electrically connected with an anode of the third diode, a third end of the third voltage stabilizing diode, a second end of the eighteenth resistor, an emitting electrode of the first triode, a second end of the twentieth resistor and a second end of the seventh capacitor are all grounded, a second end of the thirteenth resistor, a second end of the sixteenth resistor and a second end of the nineteenth resistor are all electrically connected with a first end of the secondary winding, and a cathode of the third diode is electrically connected with a second end of the secondary winding.
In one possible design, the feedback circuit is further configured to generate the first signal based on a feedback amount of the second voltage and a feedback amount of the third voltage.
In one possible design, the feedback circuit includes: the circuit comprises a second optical coupler, a seventh resistor, an eighth resistor, a second voltage stabilizing diode, a fourth capacitor, a ninth resistor, a tenth resistor, an eleventh resistor and a twelfth resistor.
Wherein, the fourth end of the second optical coupler is electrically connected with the second end of the control unit, the third end of the second optical coupler is grounded, the first end of the second optical coupler is respectively and electrically connected with the first end of the seventh resistor and the first end of the eighth resistor, the second end of the eighth resistor is respectively and electrically connected with the second end of the second optical coupler, the first end of the fourth capacitor and the first end of the second voltage stabilizing diode, the second end of the fourth capacitor is electrically connected with the first end of the ninth resistor, the second end of the ninth resistor is respectively and electrically connected with the second end of the second voltage stabilizing diode, the first end of the tenth resistor, the first end of the eleventh resistor and the first end of the twelfth resistor are electrically connected, the third end of the second zener diode tube and the second end of the eleventh resistor are both grounded, the second end of the seventh resistor and the second end of the tenth resistor are both electrically connected with the first end of the secondary winding, and the second end of the twelfth resistor is electrically connected with the second end of the secondary winding.
In a third aspect, the present application provides an electronic device, comprising: a housing and a power protection circuit in any one of the possible designs of the first aspect and the first aspect.
In one possible design, the electronic device is a television.
The beneficial effects of the electronic device provided in the third aspect and each possible design of the third aspect may refer to the beneficial effects brought by each possible implementation manner of the first aspect, and are not described herein again.
In a fourth aspect, the present application provides an electronic device comprising: a housing and a power protection circuit in any one of the possible designs of the second aspect and the second aspect.
In one possible design, the electronic device is a television.
The beneficial effects of the electronic device provided in the fourth aspect and each possible design of the fourth aspect may refer to the beneficial effects brought by each possible implementation manner of the second aspect, and are not described herein again.
Drawings
Fig. 1 is a schematic structural diagram of a power protection circuit according to an embodiment of the present disclosure;
fig. 2 is a schematic structural diagram of a first detection circuit according to an embodiment of the present disclosure;
Fig. 3 is a schematic structural diagram of a power protection circuit according to an embodiment of the present disclosure;
fig. 4 is a schematic structural diagram of a second detection circuit according to an embodiment of the present disclosure;
fig. 5 is a schematic structural diagram of a feedback circuit according to an embodiment of the present application;
fig. 6 is a schematic structural diagram of a feedback circuit according to an embodiment of the present disclosure.
Description of reference numerals:
101-a control unit; 1021 — a first transformer; 1022 — a second transformer; 103-a feedback circuit; 1041 — a first detection circuit; 1042 — a second detection circuit; l1 — primary winding; l3 — auxiliary winding; l21+ L22 — secondary winding; l21 — winding in the secondary winding that generates the second voltage; l22 — winding in the secondary winding that generates the third voltage; vin — a first voltage; vout1 — second voltage; vout2 — third voltage; vout3 — fourth voltage; FB — first signal; VCC — second signal; OVP — third signal;
VD 1-first diode; VD2 — second diode; r1 — first resistance; c1 — first capacitance; c2 — second capacitance;
r2 — second resistance; r3 — third resistor; r4 — fourth resistor; r5 — fifth resistor; r6 — sixth resistor; a Q-NMOS (N-Metal-Oxide-Semiconductor) transistor; n1 — first optocoupler; n2 — first zener diode; c3 — third capacitance;
N5 — third optocoupler; r13 — thirteenth resistor; r14 — fourteenth resistance; n6 — third zener diode; c5 — fifth capacitance; r15 — fifteenth resistor; r16 — sixteenth resistance; r17 — seventeenth resistor; r18 — eighteenth resistor; v1-first triode; r19 — nineteenth resistor; v2-second triode; r20 — twentieth resistance; c6 — sixth capacitance; c7 — seventh capacitance; r21 — twenty-first resistance; VD3 — third diode;
n3 — a second optical coupler; r7 — seventh resistor; r8 — eighth resistance; n4 — second zener diode; c4 — fourth capacitance; r9 — ninth resistor; r10 — tenth resistance; r11 — eleventh resistor; r12 — twelfth resistor.
Detailed Description
In the embodiments of the present application, "at least one" means one or more, "a plurality" means two or more. "and/or" describes the association relationship of the associated objects, meaning that there may be three relationships, e.g., a and/or B, which may mean: a exists alone, A and B exist simultaneously, and B exists alone, wherein A and B can be singular or plural. The character "/" generally indicates that the former and latter associated objects are in an "or" relationship. "at least one of the following" or similar expressions refer to any combination of these items, including any combination of the singular or plural items. For example, at least one (one) of a alone, b alone, or c alone, may represent: a alone, b alone, c alone, a and b in combination, a and c in combination, b and c in combination, or a, b and c in combination, wherein a, b and c may be single or multiple. Furthermore, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
At present, a switching power supply often has an Over Power Protection (OPP) function, that is, when the power of the power supply is too high, the OPP function can be triggered, so that the switching power supply stops working or restarts. The over-power protection function can be realized in the form of a software module, a circuit, a chip and the like.
When load impact occurs on the auxiliary circuit output, the voltage output by the auxiliary circuit is continuously reduced due to factors such as coupling and internal resistance, so that the power of the power supply is not increased or slowly increased due to continuous large current, the overpower protection function of the switching power supply cannot be triggered, the temperature rise of a power supply board device is easily overhigh due to the continuous large current, and the power supply board device is dangerous and does not meet the safety standard. In addition, the load on the auxiliary output is increased, which does not affect the voltage and current of the main output, i.e. the voltage and current of the main output are kept constant, and the over-power protection function of the switching power supply cannot be triggered.
When load impact occurs on the main circuit output, because the voltage output by the main circuit is constant, the power of the power supply is increased due to continuous large current, and an overpower protection function of the overpower switch power supply can be triggered, so that the overpower switch power supply stops working or restarts.
Based on the above description, in the embodiment of the application, when load impact occurs on the auxiliary circuit output, the voltage output by the main circuit or the power supply voltage of the control unit in the switching power supply may be raised, and then a large voltage may trigger an Over Voltage Protection (OVP) function of the switching power supply, so that the switching power supply stops working or restarts, the problem of excessive temperature rise of a power board device due to increased load on the auxiliary circuit output is solved, and the safety performance of the switching power supply is improved.
The overvoltage protection function can be realized in the form of a software module, a circuit, a chip, and the like, and specifically, the overvoltage protection function can be integrated in the control unit or can be separated from the control unit, which is not limited in the embodiment of the present application. Also, the control unit may be implemented in the form of a chip or a circuit. Such as a Micro Controller Unit (MCU) or a system on chip (SoC).
The embodiment of the application can provide two power protection strategies for triggering the overvoltage protection function:
in the first mode, the power supply voltage of the control unit is controlled to rise to trigger the overvoltage protection function.
And in the second mode, the voltage output by the main circuit is controlled to rise to trigger the overvoltage protection function.
Next, with reference to fig. 1, a specific working principle of the power protection circuit according to the embodiment of the present application that triggers the overvoltage protection function in the first mode will be described.
Referring to fig. 1, fig. 1 is a schematic structural diagram of a power protection circuit according to an embodiment of the present disclosure. As shown in fig. 1, the power protection circuit of the embodiment of the present application may include: a control unit 101, a first transformer 1021, a feedback circuit 103, and a first detection circuit 1041. Therein, the first transformer 1021 has a primary winding L1, an auxiliary winding L3 and a secondary winding L21+ L22.
The primary winding L1 is used to input a first voltage Vin. The first terminal 1 of the control unit 101 is electrically connected to the primary winding L1, and the first voltage Vin can be adjusted, so that the second voltage Vout1, the third voltage Vout2 and the fourth voltage Vout3 (i.e. the supply voltage of the control unit 101) are changed accordingly.
The secondary winding L21+ L22 is used to supply power to the load. Different ends of the secondary winding L21+ L22 may provide different outputs, including a main output and a secondary output. For convenience of illustration, the embodiment of the present application may adopt, as an example, a first end of the secondary winding L21+ L22 is used for outputting the second voltage Vout1 to the first load, a second end of the secondary winding L21+ L22 is used for outputting the third voltage Vout2 to the second load, the second voltage Vout1 is a voltage output by the main circuit, and the third voltage Vout2 is a voltage output by the auxiliary circuit. The second voltage Vout1 and the third voltage Vout2 may be voltages of the same magnitude or voltages of different magnitudes, which is not limited in the embodiments of the present application.
The auxiliary winding L3 is used for outputting a fourth voltage Vout3 to the control unit 101, and can supply power to the control unit 101, so that the control unit 101 can operate normally.
The feedback circuit 103 is electrically connected to both the first terminal 1 and the second terminal 2 of the secondary winding L21+ L22, and the feedback circuit 103 is also electrically connected to the second terminal 2 of the control unit 101.
The first detection circuit 1041 is electrically connected to the auxiliary winding L3, and the first detection circuit 1041 is further electrically connected to the third terminal 3 of the control unit 101.
When the load on the secondary output becomes larger (i.e. the second load becomes larger), the feedback circuit 103 may control the second voltage Vout1 at the output side of the transformer 1021 to become larger, i.e. control the voltage output by the primary output to become larger. And the feedback circuit 103 may send a first signal FB to the control unit 101 indicating that the second voltage Vout1 has become large. The control unit 101 may adjust the first voltage Vin at the input side of the transformer 1021 based on the first signal FB, so that the second voltage Vout1 at the output side of the transformer 1021 becomes larger.
The winding (i.e., L21) generating the second voltage Vout1 is tightly coupled between the auxiliary winding L3 and the secondary winding L21+ L22, and the second voltage Vout1 and the fourth voltage Vout3 are both generated by the same transformer (i.e., the first transformer 1021). Therefore, the fourth voltage Vout3 becomes larger as the second voltage Vout1 becomes larger due to the cross adjustment. In addition, the winding of the secondary winding L21+ L22 that generates the third voltage Vout2 is L22.
Accordingly, the first detection circuit 1041 may output the second signal VCC to the control unit 101 based on the increased fourth voltage Vout 3. Because the control unit 101 has an overvoltage protection function, when the control unit 101 receives the second signal VCC or the voltage value of the second signal VCC rises to the first preset threshold, the control unit 101 may be controlled to restart or stop working.
In this embodiment, a specific representation manner of the first signal FB and the second signal VCC is not limited, and may be a digital signal or an analog signal. In addition, the size of the first preset threshold is not limited, and the first preset threshold can be specifically set according to specific parameters and connection conditions of each component.
In summary, by means of the close coupling of the auxiliary winding L3 and the winding (i.e., L21) of the secondary winding L21+ L22 that generates the voltage of the main output (i.e., the second voltage Vout1), when the load electrically connected to the auxiliary output becomes large, the feedback circuit 103 controls the voltage of the main output (i.e., the second voltage Vout1) to be raised, so that the supply voltage of the control unit 101 output by the auxiliary winding L3 (i.e., the fourth voltage Vout3) is raised, and thus the raised supply voltage of the control unit 101 (i.e., the fourth voltage Vout3) can trigger the overvoltage protection function, so that the control unit 101 restarts or stops operating, thereby protecting various components in the whole circuit and improving the safety performance of the whole circuit.
It should be noted that the power protection circuit includes, but is not limited to, the above modules, for example, the power protection circuit may further include a standby/start module.
In some embodiments, a specific structure of the first detection circuit 1041 in fig. 1 is explained.
Referring to fig. 2, fig. 2 is a schematic structural diagram of a first detection circuit according to an embodiment of the present disclosure. As shown in fig. 2, the first detection circuit 1041 of the embodiment of the application may include: the circuit comprises a first diode VD1, a second diode VD2, a first resistor R1, a first capacitor C1 and a second capacitor C2.
The cathode of the first diode VD1 and the first end of the first capacitor C1 are electrically connected to the third end 3 of the control unit 101, the anode of the first diode VD1 is electrically connected to the first level V01, the first end of the second capacitor C2 and the cathode of the second diode VD2, the anode of the second diode VD2 is electrically connected to the first end of the first resistor R1, the second end of the first resistor R1 is electrically connected to the auxiliary winding L3, and the second end of the first capacitor C1 and the second end of the second capacitor C2 are both grounded.
In the embodiment of the present application, when the load on the auxiliary circuit output becomes larger (i.e. the second load becomes larger), the second voltage Vout1 is driven to become larger, so that the fourth voltage Vout3 becomes larger accordingly. Therefore, the first resistor R1 is connected to the fourth voltage Vout3, and is converted into the second signal VCC through the connection relationship between the first diode VD1, the second diode VD2, the first resistor R1, the first capacitor C1 and the second capacitor C2, and the second signal VCC is output to the third terminal 3 of the control unit 101 from the electrical connection position between the negative electrode of the first diode VD1 and the first terminal of the first capacitor C1, so that the control unit 101 can be controlled to restart or stop working when receiving the second signal VCC or the voltage value of the second signal VCC rises to the first preset threshold, which plays a role in protecting the whole circuit and improves the safety performance of the whole circuit.
In the embodiment of the present application, the magnitude of the first level V01 is not limited. Moreover, the first detection circuit 1041 of the embodiment of the present application includes, but is not limited to, the above implementation manners.
Next, referring to fig. 3, a specific operation principle of the power protection circuit of the present application that triggers the overvoltage protection function in the second mode is described.
Referring to fig. 3, fig. 3 is a schematic structural diagram of a power protection circuit according to an embodiment of the present application. As shown in fig. 3, the power protection circuit of the embodiment of the present application may include: a control unit 101, a second transformer 1022, a feedback circuit 103, and a second detection circuit 1042. Therein, the second transformer 1022 has a primary winding L1 and a secondary winding L21+ L22. It should be noted that, in the embodiment of the present application, there is no limitation on whether the second transformer 1022 has the auxiliary winding L3.
The primary winding L1 is used to input a first voltage Vin. The first terminal of the control unit 101 is electrically connected to the primary winding L1, and the first voltage Vin can be adjusted, so that the second voltage Vout1, the third voltage Vout2 and the fourth voltage Vout3 (i.e. the supply voltage of the control unit 101) are changed accordingly.
The secondary winding L21+ L22 is used to supply power to the load. Different ends of the secondary winding L21+ L22 may provide different outputs, including a main output and a secondary output. For convenience of illustration, the embodiment of the present application may adopt, as an example, a first end of the secondary winding L21+ L22 is used for outputting the second voltage Vout1 to the first load, a second end of the secondary winding L21+ L22 is used for outputting the third voltage Vout2 to the second load, the second voltage Vout1 is a voltage output by the main circuit, and the third voltage Vout2 is a voltage output by the auxiliary circuit. The second voltage Vout1 and the third voltage Vout2 may be voltages of the same magnitude or voltages of different magnitudes, which is not limited in the embodiments of the present application.
The feedback circuit 103 is electrically connected to both the first terminal 1 of the secondary winding L21+ L22 and the second terminal 2 of the secondary winding L21+ L22, and the feedback circuit 103 is also electrically connected to the second terminal 2 of the control unit 101.
The second detecting circuit 1042 is electrically connected to the first end of the secondary winding L21+ L22, and the second detecting circuit 1042 is also electrically connected to the third end 3 of the control unit 101.
When the load on the secondary output becomes larger (i.e. the second load becomes larger), the feedback circuit 103 may control the second voltage Vout1 at the output side of the transformer 1021 to become larger, i.e. control the voltage output by the primary output (i.e. the second voltage Vout1) to become larger. And the feedback circuit 103 may send a first signal FB to the control unit 101 indicating that the second voltage Vout1 becomes large. The control unit 101 may adjust the first voltage Vin at the input side of the transformer 1021 based on the first signal FB, so that the second voltage Vout1 at the output side of the transformer 1021 becomes larger.
Accordingly, the second detection circuit 1042 may output the third signal OVP to the control unit 101 based on the increased second voltage Vout1, e.g., the second detection circuit 1042 may send the third signal OVP to the control unit 101 when the second voltage Vout1 rises to a third preset threshold. Since the control unit 101 has the overvoltage protection function, when the control unit 101 receives the third signal OVP or the voltage value of the third signal OVP rises to the second preset threshold, the control unit 101 may be controlled to restart or stop operating.
In this embodiment, a specific representation manner of the first signal FB and the third signal OVP is not limited, and may be a digital signal or an analog signal. In addition, the second preset threshold and the third preset threshold are not limited in size in the embodiment of the application, and can be specifically set according to specific parameters and connection conditions of each component.
In summary, when the load electrically connected to the secondary output becomes larger, the feedback circuit 103 controls the voltage output by the main circuit (i.e., the second voltage Vout1) to be raised, so that the raised voltage output by the main circuit (i.e., the second voltage Vout1) can trigger the overvoltage protection function, so that the control unit 101 restarts or stops working, thereby protecting each component in the whole circuit and improving the safety performance of the whole circuit.
It should be noted that the power protection circuit includes, but is not limited to, the above modules, for example, the power protection circuit may further include a standby/start module.
In some embodiments, a specific structure of the second detection circuit 1042 in fig. 3 is explained.
Referring to fig. 4, fig. 4 is a schematic structural diagram of a second detection circuit according to an embodiment of the present disclosure. As shown in fig. 4, the second detecting circuit 1042 of the embodiment of the present application may include: the circuit comprises a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, an NMOS (N-Metal-Oxide-Semiconductor) transistor Q, a first photo-coupler N1, a first zener diode N2 and a third capacitor C3.
Wherein, the drain D of the NMOS transistor Q is electrically connected to the third terminal 3 of the control unit 101, the source S of the NMOS transistor Q is electrically connected to the first terminal of the second resistor R2, the gate G of the NMOS transistor Q is electrically connected to the second terminal of the second resistor R2 and the third terminal 3 of the first optocoupler N1, the fourth terminal 4 of the first optocoupler N1 is electrically connected to the first terminal of the third resistor R3, the second terminal of the third resistor R3 is electrically connected to the second level V02, the first terminal 1 of the first optocoupler N1 is electrically connected to the first terminal of the fourth resistor R4, the second terminal 2 of the first optocoupler N1 is electrically connected to the first terminal of the first zener diode N2, the second terminal of the first zener diode N2 is electrically connected to the first terminal of the third capacitor C3, the first terminal of the fifth resistor R5 and the first terminal of the sixth resistor R6, the third terminal of the first zener diode N2, the third terminal C3 of the third capacitor C3 and the second terminal of the sixth resistor R6 are electrically connected to the ground, a second terminal of the fourth resistor R4 and a second terminal of the fifth resistor R5 are both electrically connected to a first terminal of the secondary winding L21+ L22.
In the embodiment of the present application, when the load on the secondary output becomes larger (i.e., the second load becomes larger), the second voltage Vout1 is driven to become larger. Therefore, the second voltage Vout1 is connected to an electrical connection position between the second end of the fourth resistor R4 and the second end of the fifth resistor R5, and is converted into a third signal OVP through a connection relationship between the second resistor R2, the third resistor R3, the fourth resistor R4, the fifth resistor R5, the sixth resistor R6, the NMOS transistor Q, the first photo-coupler N1, the first zener diode N2, and the third capacitor C3, and the third signal OVP is output to the control unit 101 from the drain of the NMOS transistor Q, so that when the control unit 101 receives the third signal OVP or the voltage value of the third signal OVP rises to a second preset threshold, the control unit 101 may be controlled to restart or stop operating, which plays a role in protecting the entire circuit, and improves the safety performance of the entire circuit.
It should be noted that the NMOS transistor Q may be replaced by one or more transistors of other types. The second level V02 is not limited in size in the embodiment of the present application. Moreover, the first detection circuit 1041 of the embodiment of the present application includes, but is not limited to, the above implementation manners.
In some embodiments, a specific structure of the feedback circuit 103 in fig. 1 or fig. 3 is explained.
In the embodiment of the present application, when the load on the auxiliary circuit output becomes large (i.e., the second load becomes large), the feedback circuit 103 may control the second voltage Vout1 to become large and send the first signal FB indicating that the second voltage Vout1 becomes large to the control unit 101. Accordingly, the control unit 101 adjusts the first voltage Vin based on the first signal FB to drive the second voltage Vout1 or the fourth voltage Vout3 to become large.
In some embodiments, the first signal FB is related to the amount of feedback of the second voltage Vout 1. Next, a specific implementation process of the feedback circuit 103 in fig. 1 or fig. 3 sending the first signal FB to the control unit 101 based on the feedback amount of the second voltage Vout1 will be explained.
Referring to fig. 5, fig. 5 is a schematic structural diagram of a feedback circuit according to an embodiment of the present disclosure. As shown in fig. 5, the feedback circuit 103 of the embodiment of the present application may include: a third optical coupler N5, a thirteenth resistor R13, a fourteenth resistor R14, a third zener diode N6, a fifth capacitor C5, a fifteenth resistor R15, a sixteenth resistor R16, a seventeenth resistor R17, an eighteenth resistor R18, a first triode V1 (illustrated by an NPN-type triode in fig. 5), a nineteenth resistor R19, a second triode V2 (illustrated by a PNP-type triode in fig. 5), a twentieth resistor R20, a sixth capacitor C6, a seventh capacitor C7, a twenty-first resistor R21, and a third diode VD 3.
A fourth end 4 of the third optocoupler N5 is electrically connected to the second end 2 of the control unit 101, a third end 3 of the third optocoupler N5 is grounded, a first end 1 of the third optocoupler N5 is electrically connected to the first end of the thirteenth resistor R13 and the first end of the fourteenth resistor R14, respectively, a second end of the fourteenth resistor R14 is electrically connected to the second end 2 of the third optocoupler N5, the first end of the fifth capacitor C5 and the first end of the third zener diode N6, respectively, the second end of the fifth capacitor C5 is electrically connected to the first end of the fifteenth resistor R15, the second end of the fifteenth resistor R15 is electrically connected to the first end of the seventeenth resistor R17, the first end of the eighteenth resistor R18 and the second end of the third zener diode N6, the second end of the seventeenth resistor R17 is electrically connected to the first end of the sixteenth resistor R16 and the collector of the first triode V1, respectively, and a base of the first V1 of the second triode V2 is electrically connected to the collector of the second triode 2, A first end of a twentieth resistor R20 is electrically connected with a first end of a seventh capacitor C7, an emitter of a second triode V2 is respectively and electrically connected with a first end of a nineteenth resistor R19 and a first end of a sixth capacitor C6, a base of a second triode V2 is respectively and electrically connected with a second end of the sixth capacitor C6 and a first end of a twenty-first resistor R21, a second end of the twenty-first resistor R21 is electrically connected with an anode of a third diode VD3, a third end of a third voltage-stabilizing diode N6, a second end of an eighteenth resistor R18 and an emitter of a first triode V1, a second end of the twentieth resistor R20 and a second end of the seventh capacitor C7 are both grounded, a second end of the thirteenth resistor R13, a second end of the sixteenth resistor R16 and a second end of the nineteenth resistor R19 are both electrically connected to the first end of the secondary winding L21+ L22, and a cathode of the third diode VD3 is electrically connected to the second end of the secondary winding L21+ L22.
In the embodiment of the present application, when the load on the secondary output becomes larger (i.e., the second load becomes larger), the third diode VD3 is connected to the third voltage Vout2, and the second end of the thirteenth resistor R13, the second end of the sixteenth resistor R16 and the second end of the nineteenth resistor R19 are connected to the second voltage Vout 1. Since the third voltage Vout2 drops, for example, the third voltage Vout2 is 18V and the second voltage Vout1 is 12V. When the third voltage Vout2 drops to a voltage drop 12V-1.2V-10.8V between the third diode VD3 and the second transistor V2, the second transistor V2 is turned on, and the first transistor V1 is turned on, so that the sampling voltage-dividing ratio of the second voltage Vout1 is changed, and the second voltage Vout1 is raised. The third photo-coupler N5 converts the feedback quantity of the second voltage Vout1 into a first signal FB, and the fourth terminal 4 of the third photo-coupler N5 outputs the first signal FB to the control unit 101, so that the control unit 101 adjusts the first voltage Vin based on the first signal FB to increase the second voltage Vout1 or the fourth voltage Vout 3.
The third diode VD3 plays a role in isolating the third voltage Vout2, preventing the third voltage Vout2 from breaking down the junction between the base and the emitter of the second transistor V2 during normal operation, the nineteenth resistor R19, the twenty-first resistor R21, and the sixth capacitor C6 play an integral role, and limit the base current of the second transistor V2, because: because the transient inrush current is needed to avoid the malfunction of the circuit, even if the third voltage Vout2 drops to a very low value (e.g. 10V) instantaneously, the second transistor V2 does not conduct immediately, and when the sixth capacitor C6 is charged by the second voltage Vout1 through the nineteenth resistor R19 and the twenty-first resistor R21 to the voltage (e.g. 0.6V) between the base and the emitter of the second transistor V2, the second transistor V2 will conduct, and start the protection circuit. Therefore, the action point of the overcurrent protection and the delay time of the transient impact can be adjusted by adjusting the values of the nineteenth resistor R19, the twenty-first resistor R21 and the sixth capacitor C6.
The sixteenth resistor R16 and the seventeenth resistor R17 are used together as an upper end resistor for feedback sampling of the second voltage Vout1, and the collector of the first transistor V1 is connected to the serial node of the sixteenth resistor R16 and the seventeenth resistor R17 to improve the sensitivity of the circuit operation. Therefore, the second voltage Vout1 rises greatly to trigger the over-voltage protection immediately after the second transistor V2 starts to operate. The twentieth resistor R20 and the seventh capacitor C7 realize the static bias and the anti-interference capability of the first triode V1.
It should be noted that the feedback circuit 103 of the present application includes, but is not limited to, the above implementation.
In other embodiments, the first signal FB is related to the sum of the feedback amount of the second voltage Vout1 and the feedback amount of the third voltage Vout 2. Next, a specific implementation procedure in which the feedback circuit 103 in fig. 1 or fig. 3 transmits the first signal FB to the control unit 101 based on the sum of the feedback amount of the second voltage Vout1 and the feedback amount of the third voltage Vout2 will be explained.
Referring to fig. 6, fig. 6 is a schematic structural diagram of a feedback circuit according to an embodiment of the present disclosure. As shown in fig. 6, the feedback circuit 103 of the embodiment of the present application may include: the circuit comprises a second optical coupler N3, a seventh resistor R7, an eighth resistor R8, a second zener diode N4, a fourth capacitor C4, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11 and a twelfth resistor R12.
Wherein, the fourth end 4 of the second optical coupler N3 is electrically connected to the second end 2 of the control unit 101, the third end 3 of the second optical coupler N3 is grounded, the first end 1 of the second optical coupler N3 is electrically connected to the first end of the seventh resistor R7 and the first end of the eighth resistor R8, respectively, the second end of the eighth resistor R8 is electrically connected to the second end 2 of the second optical coupler N3, the first end of the fourth capacitor C4 and the first end of the second zener diode N4, respectively, the second end of the fourth capacitor C4 is electrically connected to the first end of the ninth resistor R9, the second end of the ninth resistor R9 is electrically connected to the second end of the second zener diode N4, the first end of the tenth resistor R10, the first end of the eleventh resistor R11 and the first end of the twelfth resistor R12, respectively, the third end of the second zener diode N2 and the second end of the eleventh resistor R56 are grounded, the second end of the seventh resistor R6353 and the second end R867 are electrically connected to the second end 867 of the secondary winding 86847, a second end of the twelfth resistor R12 is electrically connected to a second end of the secondary winding L21+ L22.
In the embodiment of the present application, when a load (i.e., a second load) on the auxiliary circuit output becomes large, the second end of the seventh resistor R7 and the second end of the tenth resistor R10 are connected to the second voltage Vout1, and the second end of the twelfth resistor R12 is connected to the third voltage Vout 2. Since the third voltage Vout2 will drop and the feedback amount of the third voltage Vout2 is small, the seventh resistor R7, the eighth resistor R8, the second zener diode N4, the fourth capacitor C4, the ninth resistor R9, the tenth resistor R10, the eleventh resistor R11 and the twelfth resistor R12 are electrically connected to drive the second voltage Vout1 to increase, so that the sum of the feedback amount of the second voltage Vout1 and the feedback amount of the third voltage Vout2 is increased. The second photo-coupler N3 converts the sum of the feedback amount of the second voltage Vout1 and the feedback amount of the third voltage Vout2 into the first signal FB, and the fourth terminal 4 of the second photo-coupler N3 outputs the first signal FB to the control unit 101, so that the control unit 101 adjusts the first voltage Vin based on the first signal FB to increase the second voltage Vout1 or the fourth voltage Vout 3.
It should be noted that the feedback circuit 103 according to the embodiment of the present application includes, but is not limited to, the foregoing implementation.
Exemplarily, the embodiment of the application further provides an electronic device. The electronic device of the embodiment of the application may include: a housing and a power protection circuit in the foregoing embodiments.
In some embodiments, the electronic device may be a television. The first load is a main board inside the television, and the first end of the secondary winding can output a second voltage (for example, 12V) to the main board. The second load is an audio circuit inside the television, and the second end of the secondary winding can output a third voltage (e.g. 18V) to the audio circuit.
In other embodiments, the electronic device may be a printer. The first load is a control circuit inside the printer, and the first end of the secondary winding can output a second voltage (e.g. 5V) to the control circuit. The second load is an ink jet motor internal to the printer, and the second end of the secondary winding may output a third voltage (e.g., 18V) to the ink jet motor.
Finally, it should be noted that: the above embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill 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; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present application.

Claims (10)

1. A power protection circuit, comprising:
the device comprises a control unit, a first transformer, a feedback circuit and a first detection circuit;
the first transformer is provided with a primary winding, an auxiliary winding and a secondary winding, wherein the primary winding is used for inputting a first voltage, a first end of the secondary winding is used for outputting a second voltage to a first load, a second end of the secondary winding is used for outputting a third voltage to a second load, the auxiliary winding is used for outputting a fourth voltage to the control unit, the auxiliary winding is closely coupled with a winding generating the second voltage in the secondary winding, the primary winding is used for electrically connecting the first end of the control unit, the first end and the second end of the secondary winding are both used for electrically connecting the feedback circuit, the feedback circuit is also electrically connected with the second end of the control unit, the auxiliary winding is used for electrically connecting the first detection circuit, and the first detection circuit is also electrically connected with the third end of the control unit;
the feedback circuit is used for controlling the second voltage to become larger when the second load becomes larger and sending a first signal to the control unit, wherein the first signal is used for indicating that the second voltage becomes larger;
The control unit is used for controlling the fourth voltage to be increased when the first signal is received;
the first detection circuit is configured to output a second signal to the control unit, where the second signal is related to the fourth voltage;
the control unit is further configured to control the control unit to restart or stop working when the second signal is received or the voltage value of the second signal rises to a first preset threshold.
2. The circuit of claim 1, wherein the first detection circuit comprises: the circuit comprises a first diode, a second diode, a first resistor, a first capacitor and a second capacitor;
the negative electrode of the first diode and the first end of the first capacitor are electrically connected with the third end of the control unit, the positive electrode of the first diode is electrically connected with the first level, the first end of the second capacitor and the negative electrode of the second diode respectively, the positive electrode of the second diode is electrically connected with the first end of the first resistor, the second end of the first resistor is electrically connected with the auxiliary winding, and the second end of the first capacitor and the second end of the second capacitor are grounded.
3. A power protection circuit, comprising:
the control unit, the second transformer, the feedback circuit and the second detection circuit;
the second transformer is provided with a primary winding and a secondary winding, the primary winding is used for inputting a first voltage, a first end of the secondary winding is used for outputting a second voltage to a first load, a second end of the secondary winding is used for outputting a third voltage to a second load, the primary winding is used for being electrically connected with a first end of the control unit, the first end and the second end of the secondary winding are both used for being electrically connected with the feedback circuit, the feedback circuit is also electrically connected with the second end of the control unit, the first end of the secondary winding is electrically connected with the second detection circuit, and the second detection circuit is electrically connected with a third end of the control unit;
the feedback circuit is used for controlling the second voltage to become larger when the second load becomes larger, and sending a first signal to the control unit, wherein the first signal is used for indicating that the second voltage becomes larger;
the control unit is used for controlling the second voltage to be increased when the first signal is received;
the second detection circuit is used for outputting a third signal to the control unit, wherein the third signal is related to the second voltage;
The control unit is further configured to control the control unit to restart or stop working when the third signal is received or the voltage value of the third signal rises to a second preset threshold.
4. The circuit of claim 3, wherein the second detection circuit comprises: the second resistor, the third resistor, the fourth resistor, the fifth resistor, the sixth resistor, the NMOS transistor, the first optical coupler, the first voltage stabilizing diode and the third capacitor;
the drain of the NMOS transistor is electrically connected to the third end of the control unit, the source of the NMOS transistor is grounded to the first end of the second resistor, the gate of the NMOS transistor is electrically connected to the second end of the second resistor and the third end of the first optocoupler, the fourth end of the first optocoupler is electrically connected to the first end of the third resistor, the second end of the third resistor is electrically connected to the second level, the first end of the first optocoupler is electrically connected to the first end of the fourth resistor, the second end of the first optocoupler is electrically connected to the first end of the first zener diode, the second end of the first zener diode is electrically connected to the first end of the third capacitor, the first end of the fifth resistor and the first end of the sixth resistor, the third end of the first zener diode, the first end of the second zener diode, the second end of the third zener diode, the second end of the fourth resistor, and the third end of the fourth resistor are electrically connected to the fourth zener diode, And the second end of the third capacitor and the second end of the sixth resistor are both grounded, and the second end of the fourth resistor and the second end of the fifth resistor are both electrically connected with the first end of the secondary winding.
5. The circuit of any of claims 1-4, wherein the feedback circuit is further configured to generate the first signal based on a feedback amount of the second voltage.
6. The circuit of claim 5, wherein the feedback circuit comprises: a third optical coupler, a thirteenth resistor, a fourteenth resistor, a third zener diode, a fifth capacitor, a fifteenth resistor, a sixteenth resistor, a seventeenth resistor, an eighteenth resistor, a first triode, a nineteenth resistor, a second triode, a twentieth resistor, a sixth capacitor, a seventh capacitor, a twenty-first resistor and a third diode;
wherein a fourth end of the third optical coupler is electrically connected to a second end of the control unit, a third end of the third optical coupler is grounded, a first end of the third optical coupler is electrically connected to a first end of the thirteenth resistor and a first end of the fourteenth resistor, respectively, a second end of the fourteenth resistor is electrically connected to a second end of the third optical coupler, a first end of the fifth capacitor and a first end of the third zener diode, a second end of the fifth capacitor is electrically connected to a first end of the fifteenth resistor, a second end of the fifteenth resistor is electrically connected to a first end of the seventeenth resistor, a first end of the eighteenth resistor and a second end of the third zener diode, respectively, a second end of the seventeenth resistor is electrically connected to a first end of the sixteenth resistor and a collector of the first triode, respectively, the base of the first triode is respectively and electrically connected with the collector of the second triode, the first end of the twentieth resistor and the first end of the seventh capacitor, the emitter of the second triode is respectively and electrically connected with the first end of the nineteenth resistor and the first end of the sixth capacitor, the base of the second triode is respectively and electrically connected with the second end of the sixth capacitor and the first end of the twenty-first resistor, the second end of the twenty-first resistor is electrically connected with the anode of the third diode, the third end of the third zener diode, the second end of the eighteenth resistor, the emitter of the first triode, the second end of the twentieth resistor and the second end of the seventh capacitor are all grounded, the second end of the thirteenth resistor, the second end of the sixteenth resistor and the second end of the nineteenth resistor are all electrically connected with the first end of the secondary winding, the cathode of the third diode is electrically connected with the second end of the secondary winding.
7. The circuit of any of claims 1-4, wherein the feedback circuit is further configured to generate the first signal based on a feedback amount of the second voltage and a feedback amount of the third voltage.
8. The circuit of claim 7, wherein the feedback circuit comprises: the second optical coupler, the seventh resistor, the eighth resistor, the second voltage stabilizing diode, the fourth capacitor, the ninth resistor, the tenth resistor, the eleventh resistor and the twelfth resistor;
wherein a fourth end of the second optical coupler is electrically connected to a second end of the control unit, a third end of the second optical coupler is grounded, a first end of the second optical coupler is electrically connected to a first end of the seventh resistor and a first end of the eighth resistor, a second end of the eighth resistor is electrically connected to a second end of the second optical coupler, a first end of the fourth capacitor and a first end of the second zener diode, a second end of the fourth capacitor is electrically connected to a first end of the ninth resistor, a second end of the ninth resistor is electrically connected to a second end of the second zener diode, a first end of the tenth resistor, a first end of the eleventh resistor and a first end of the twelfth resistor, respectively, a third end of the second zener diode and a second end of the eleventh resistor are both grounded, a second end of the seventh resistor and a second end of the tenth resistor are both electrically connected to the first end of the secondary winding, and a second end of the twelfth resistor is electrically connected to the second end of the secondary winding.
9. An electronic device, comprising:
a housing and a power protection circuit as claimed in any one of claims 1 to 8.
10. The device of claim 9, wherein the electronic device is a television.
CN202011211372.0A 2020-09-02 2020-11-03 Power protection circuit and electronic device Active CN112350279B (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11206116A (en) * 1998-01-19 1999-07-30 Nagano Japan Radio Co Constant voltage constant current power unit
CN101699686A (en) * 2009-11-19 2010-04-28 中兴通讯股份有限公司 Protection device of switch power supply and method thereof
CN204068678U (en) * 2014-06-19 2014-12-31 深圳市聚电电源技术有限公司 A kind of Switching Power Supply output over-voltage protection and thermal-shutdown circuit
CN104300796A (en) * 2014-10-21 2015-01-21 陕西华经微电子股份有限公司 DC/DC converter capable of automatically adjusting minimum fixed output current in semi-control state
CN105813263A (en) * 2016-04-22 2016-07-27 深圳创维-Rgb电子有限公司 Switching power supply and television

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH11206116A (en) * 1998-01-19 1999-07-30 Nagano Japan Radio Co Constant voltage constant current power unit
CN101699686A (en) * 2009-11-19 2010-04-28 中兴通讯股份有限公司 Protection device of switch power supply and method thereof
CN204068678U (en) * 2014-06-19 2014-12-31 深圳市聚电电源技术有限公司 A kind of Switching Power Supply output over-voltage protection and thermal-shutdown circuit
CN104300796A (en) * 2014-10-21 2015-01-21 陕西华经微电子股份有限公司 DC/DC converter capable of automatically adjusting minimum fixed output current in semi-control state
CN105813263A (en) * 2016-04-22 2016-07-27 深圳创维-Rgb电子有限公司 Switching power supply and television

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