Printed circuit board assembly and device protection circuit thereof

Abstract

The utility model discloses a printed circuit board assembly and a device protection circuit thereof, belongs to the field of electronic circuits, and aims to solve the problems that (1) before a fire or explosion accident occurs, a component on a PBA of electric equipment usually has high temperature, and (2) when a voltage detection pin of a switch chip of a power supply detects a lower voltage, the power supply can be switched off, and the power supply cannot be switched off. Therefore, the temperature sensing circuit can drive the controllable switch to be switched on when the sensed temperature is too high, the voltage detection pin of the switch chip is pulled down through the photoelectric coupler, the power supply is turned off, fire and explosion accidents of electric equipment are prevented, potential safety hazards are eliminated, and the safety of the electric equipment is improved. And the power supply can be switched off at high temperature by controlling the voltage detection pin of the switch chip, so that the circuit is simple in structure and relatively low in cost.

Description

TECHNICAL FIELD

[0001] The utility model relates to electronic circuit field especially, it is a kind of printed circuit board assembly and its device protection circuit. BACKGROUND

[0002] Electric equipment can appear accidental fire even explosion accident due to some reasons (for example component aging or load anomaly etc.), however, lack a mature device protection circuit in the related art, cannot prevent the accidental fire and explosion failure of electric equipment in time, to cause electric equipment in use process can be on fire even explosion, and the security risk is bigger. UTILITY MODEL CONTENTS

[0003] The utility model aims at providing a kind of printed circuit board assembly and its device protection circuit, temperature sensing circuit in the utility model can drive controllable switch to be conducted when the temperature sensed is too high, and then the voltage detection pin of switch chip is pulled low by photoelectric coupler, to make power disconnected, prevent electric equipment from producing fire and explosion accident, eliminate the security risk, and the voltage detection pin of switch chip is controlled to disconnect power supply at high temperature, circuit structure is simple, and cost is lower.

[0004] To solve the above technical problem, the utility model provides a kind of device protection circuit, including voltage source, temperature sensing circuit, controllable switch and photoelectric coupler;

[0005] The voltage source is connected with the input end of the temperature sensing circuit and the photoelectric coupler respectively, the temperature sensing circuit is connected with the control end of the controllable switch, the input end of the photoelectric coupler is connected with the first end of the controllable switch, the second end of the controllable switch is grounded, the output end of the photoelectric coupler is connected with the voltage detection pin of the switch chip of power supply in printed circuit board assembly and ground respectively, the temperature sensing circuit is arranged in printed circuit board assembly;

[0006] The temperature sensing circuit is used to drive the controllable switch to be conducted when the temperature sensed is too high, so that the input end of the photoelectric coupler is electrified;

[0007] The photoelectric coupler is used to be conducted at the output end when the input end is electrified, so as to ground the voltage detection pin of the switch chip of power supply in printed circuit board assembly.

[0008] In another aspect, the temperature sensing circuit includes voltage dividing resistor pair;

[0009] The voltage divider resistor pair comprises a first resistor and a thermistor connected in series with the first resistor, a first end of the voltage divider resistor pair is connected with the voltage source, a second end of the voltage divider resistor pair is grounded, and a connection point of the first resistor and the thermistor is connected with the control end of the controllable switch.

[0010] In another aspect, the thermistor comprises a positive temperature coefficient thermistor.

[0011] The first end of the first resistor serves as the first end of the voltage divider resistor pair, the second end of the first resistor is connected with the first end of the thermistor, and the second end of the thermistor serves as the second end of the voltage divider resistor pair.

[0012] The controllable switch is configured to be turned on when the voltage value of the control end voltage is higher than a preset threshold value.

[0013] In another aspect, the controllable switch comprises an N-channel metal-oxide-semiconductor field effect transistor.

[0014] In another aspect, the device protection circuit further comprises a filtering circuit for filtering.

[0015] The filtering circuit is connected in parallel with the output end of the optoelectronic coupler.

[0016] In another aspect, the device protection circuit further comprises a current limiting circuit for limiting current.

[0017] The current limiting circuit is connected in series between the voltage source and the input end of the optoelectronic coupler.

[0018] In another aspect, the thermistor comprises a plurality of thermistor sub-resistors arranged at different positions of a printed circuit board assembly.

[0019] The plurality of thermistor sub-resistors are connected in series.

[0020] In another aspect, the temperature sensing circuit comprises a temperature sensor and a processor.

[0021] The temperature sensor is arranged on a printed circuit board assembly, the temperature sensor and the processor are respectively connected with the voltage source, and the processor is connected with the temperature sensor.

[0022] The temperature sensor is configured to feed back a detected temperature value to the processor, so that the processor drives the controllable switch to be turned on when the temperature value is too high.

[0023] In another aspect, the device protection circuit further comprises:

[0024] A prompter connected with the processor, configured to prompt the temperature value and / or the on-off state of the switch chip under the control of the processor.

[0025] To solve the above technical problems, the utility model also provides a kind of printed circuit board assembly, including the switch chip of power supply and the device protection circuit as described above connected with the switch chip.

[0026] Beneficial effect: the utility model provides a kind of device protection circuit, (1) considering that the component on the PBA of electric equipment usually appears high temperature before the occurrence of fire or explosion accident, (2)the voltage detection pin of switch chip of power supply can disconnect power supply when detecting lower voltage, therefore, temperature sensing circuit in the utility model can drive controllable switch to conduct when the temperature sensed is too high, and then the voltage detection pin of switch chip is pulled low by photoelectric coupler, promotes power supply to disconnect, prevents electric equipment to produce fire and explosion accident, eliminates security risk, and by the control of voltage detection pin of switch chip, power supply can be disconnected at high temperature, circuit structure is simple, and cost is lower.

[0027] The utility model also provides a kind of printed circuit board assembly, with the same beneficial effect as above device protection circuit. DRAWINGS

[0028] In order to more clearly illustrate the technical scheme in the utility model embodiment, the related technology and the drawing needed to be used in the embodiment will be simply introduced below, and obviously, the drawing in the following description is only some embodiments of the utility model, and for those skilled in the art, other drawings can be obtained without creative labor according to these drawings.

[0029] Figure 1 The structure diagram of a kind of device protection circuit provided by the utility model is shown;

[0030] Figure 2 The structure diagram of another device protection circuit provided by the utility model is shown. CONCRETE EMBODIMENT

[0031] The core of the utility model is to provide a kind of printed circuit board assembly and its device protection circuit, temperature sensing circuit in the utility model can drive controllable switch to conduct when the temperature sensed is too high, and then the voltage detection pin of switch chip is pulled low by photoelectric coupler, promotes power supply to disconnect, prevents electric equipment to produce fire and explosion accident, eliminates security risk, and by the control of voltage detection pin of switch chip, power supply can be disconnected at high temperature, circuit structure is simple, and cost is lower.

[0032] In order to make the purpose, technical scheme and advantages of the embodiments of the utility model clearer, the technical scheme in the embodiments of the utility model will be described clearly and completely in combination with the drawings in the embodiments of the utility model below. Obviously, the described embodiments are part of the embodiments of the utility model, rather than all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the ordinary skilled in the art without creative labor belong to the protection scope of the utility model.

[0033] Please refer to Figure 1 , Figure 1 The utility model provides a kind of device protection circuit's structural diagram, and the device protection circuit includes voltage source 1, temperature sensing circuit 2, controllable switch 3 and photoelectric coupler 4;

[0034] Voltage source 1 is connected with temperature sensing circuit 2 and the first end of photoelectric coupler 4 respectively, temperature sensing circuit 2 is connected with the control end of controllable switch 3, the first end of photoelectric coupler 4 is connected with the first end of controllable switch 3, the second end of controllable switch 3 is grounded, the second end of photoelectric coupler 4 is connected with the voltage detection pin of the switch chip of power supply in printed circuit board assembly and ground respectively, temperature sensing circuit 2 is arranged in printed circuit board assembly;

[0035] Temperature sensing circuit 2 is used to drive controllable switch 3 to conduct when the temperature sensed is too high, so that the first end of photoelectric coupler 4 is electrified;

[0036] Photoelectric coupler 4 is used to make the output end conduct when the input end is electrified, so that the voltage detection pin of the switch chip of power supply in printed circuit board assembly is grounded.

[0037] Specifically, considering the technical problems in the above background art, and combining with (1) the components on the PBA (Printed Board Assembly, printed circuit board assembly) of the electric equipment will usually appear high temperature before fire or explosion accident occurs, (2) the voltage detection pin of the switch chip of power supply can be disconnected when detecting lower voltage, therefore, in the embodiments of the utility model, when the temperature on PBA is too high, the voltage detection pin of the switch chip of power supply is set to low level, so that the switch chip disconnects the power supply under the condition of considering that low voltage is detected, so that the high temperature area on PBA will not be further heated, thereby avoiding the occurrence of fire and explosion accident.

[0038] Specific, considering that the optocoupler 4 can realize high low voltage isolation, thereby preventing high voltage for the chip caused by interference and damage, and through the on-off control of the controllable switch 3, the conduction control for the optocoupler 4 can be realized, therefore the temperature sensing circuit 2 is arranged in the embodiment of the utility model, which can drive the controllable switch 3 to conduct when the temperature sensed is too high, so that the first end of the optocoupler 4 is electrified, and then the voltage detection pin of the switch chip is pulled low through the second end of the optocoupler 4, finally the switch chip is powered off, that is, the power supply of the electrical equipment is cut off.

[0039] Wherein, it is worth mentioning that the switch chip of the power supply usually detects the supply loop voltage through the voltage detection pin, if the detected voltage value is too low, it is considered that an abnormality occurs, and the power supply is controlled to be disconnected, therefore, when the power supply is desired to be turned off under the condition of "temperature being too high", the embodiment of the utility model can realize the over-temperature protection for the electrical equipment at low cost and small size by the way of pulling the voltage detection pin of the switch chip low.

[0040] Wherein, the power supply of the electrical equipment can be of various types, for example, can be a switching power supply, etc., which is not limited in the embodiment of the utility model.

[0041] Specifically, the voltage source 1 is used to provide voltage for the temperature sensing circuit 2 and the optocoupler 4.

[0042] The utility model provides a kind of device protection circuit, considering (1) before the occurrence of fire or explosion accident, the component on the PBA of electrical equipment usually appears high temperature, (2) the voltage detection pin of the switch chip of power supply can disconnect power when detecting lower voltage, therefore, the temperature sensing circuit in the utility model can drive controllable switch to conduct when the temperature sensed is too high, and then the voltage detection pin of switch chip is pulled low by optocoupler, to make power disconnect, prevent electrical equipment from producing fire and explosion accident, eliminate security risk, and the voltage detection pin of switch chip is controlled to disconnect power when high temperature, circuit structure is simple, and cost is lower.

[0043] On the basis of the above embodiment:

[0044] As an optional embodiment, the temperature sensing circuit 2 includes a voltage dividing resistor pair;

[0045] The voltage dividing resistor pair includes a first resistor and a thermistor connected in series with the first resistor, the first end of the voltage dividing resistor pair is connected with the voltage source 1, the second end of the voltage dividing resistor pair is grounded, and the connection point of the first resistor and the thermistor is connected with the control end of the controllable switch 3.

[0046] Specifically, considering that the state control of the controllable switch 3 can be realized by adjusting the voltage value of the voltage received by the control end of the controllable switch 3, the voltage value of the voltage received by the control end of the controllable switch 3 can be controlled at low cost by using a simple structure of the voltage dividing resistor pair, and by setting one of the resistors in the voltage dividing resistor pair as a thermistor, the temperature detection can be realized, and the state change of the controllable switch 3 can be driven by the temperature change, so the voltage dividing resistor pair including the first resistor and the thermistor is used in the embodiment of the utility model, which has the advantages of simple structure and low cost.

[0047] Of course, in addition to the voltage dividing resistor pair including the first resistor and the thermistor, the temperature sensing circuit 2 can also be of other types, which are not limited in the embodiment of the utility model.

[0048] As an optional embodiment, the thermistor includes a positive temperature coefficient thermistor;

[0049] The first end of the first resistor is the first end of the voltage dividing resistor pair, the second end of the first resistor is connected with the first end of the thermistor, and the second end of the thermistor is the second end of the voltage dividing resistor pair.

[0050] The controllable switch 3 is used to be turned on when the voltage value of the control end voltage is higher than a preset threshold.

[0051] Specifically, in order to better illustrate the embodiment of the utility model, please refer to Figure 2 , Figure 2 The structure diagram of another device protection circuit provided by the utility model is shown in Figure 2 , R147 is the first resistor (the resistance value can be 47K ohms), PTC103 is a positive temperature coefficient thermistor (the model can be BSC020), +12V is the output voltage of the voltage source 1, Q104 is the controllable switch 3 (the model can be MMBT7002K), PC105 is the optocoupler 4 (the model can be PS2561AL), and P_GND and SGND are both ground.

[0052] Specifically, considering that the PTC (Positive Temperature Coefficient, positive temperature coefficient) thermistor has the advantages of good temperature stability, self-recovery over-temperature protection, surge current prevention and no low-temperature failure risk compared with the NTC (Negative Temperature Coefficient, negative temperature coefficient) thermistor, therefore, the PTC thermistor is selected in the embodiment of the utility model, and correspondingly, the thermistor is arranged on the side close to the ground, and the controllable switch 3 can be turned on when the voltage value of the control end voltage is higher than a preset threshold.

[0053] Of course, in addition to the PTC thermistor, the thermistor can be of other types, and the embodiments of the present application do not limit the same.

[0054] As an optional embodiment, the controllable switch 3 comprises an N-channel metal-oxide-semiconductor field effect transistor.

[0055] Specifically, considering that the NMOS (N-Channel Metal-Oxide-Semiconductor) has the advantages of fast response speed, simple process and low cost, the NMOS is selected as the controllable switch 3 in the embodiments of the present application.

[0056] Of course, in addition to the NMOS, the controllable switch 3 can be of other types, and the embodiments of the present application do not limit the same.

[0057] As an optional embodiment, the device protection circuit further comprises a filtering circuit for filtering;

[0058] The filtering circuit is connected in parallel with the second end of the optoelectronic coupler 4.

[0059] Specifically, considering that there can be high-frequency noise and voltage ripple interference on the voltage detection pin of the switch chip, the filtering circuit can be used to filter out the high-frequency noise and reduce the influence of the voltage ripple in the embodiments of the present application, so as to stabilize the detection voltage.

[0060] The filtering circuit can be of various types, such as a capacitor (e.g. Figure 2 The capacitor C158 in the filtering circuit can be of various types, and the embodiments of the present application do not limit the same.

[0061] As an optional embodiment, the device protection circuit further comprises a current limiting circuit for current limiting;

[0062] The current limiting circuit is connected in series between the voltage source 1 and the first end of the optoelectronic coupler 4.

[0063] Specifically, in order to prevent the inrush current in the loop from damaging the switch coupler lamp device, the current limiting circuit connected in series between the voltage source 1 and the first end of the optoelectronic coupler 4 is further provided in the embodiments of the present application.

[0064] The current limiting circuit can be of various types, such as a current limiting resistor (e.g. Figure 2 The resistor R146 in the current limiting circuit can be of various types, and the embodiments of the present application do not limit the same.

[0065] As an optional embodiment, the thermistor comprises a plurality of thermistor sub-resistors arranged at different positions of the printed circuit board assembly.

[0066] The connection mode of the plurality of thermistor sub-resistors is series connection.

[0067] Specifically, considering that (1) the plurality of thermistor sub-resistors can be used to monitor the plurality of temperature monitoring points, and (2) the resistance value of any one of the plurality of series-connected thermistor sub-resistors changes, which causes the resistance value of the entire thermistor to change, thereby causing the voltage value between the first resistor of the voltage dividing resistor pair and the thermistor to change, and the controllable switch 3 is driven, the thermistor in the embodiment of the utility model comprises a plurality of thermistor sub-resistors arranged at different positions of the printed circuit board assembly.

[0068] Of course, in addition to this specific form, the thermistor can also be 1, and the embodiment of the utility model does not limit this

[0069] As an optional embodiment, the temperature sensing circuit 2 comprises a temperature sensor and a processor.

[0070] The temperature sensor is arranged on the printed circuit board assembly, the temperature sensor and the processor are connected with the voltage source 1, and the processor is connected with the temperature sensor.

[0071] The temperature sensor is arranged on the printed circuit board assembly, the temperature sensor and the processor are connected with the voltage source 1, and the processor is connected with the temperature sensor.

[0072] Specifically, considering that the temperature sensor can also be used for temperature detection, and the processor can drive the controllable switch 3 to be turned on, the temperature sensing circuit 2 in the embodiment of the utility model comprises a temperature sensor and a processor, which is simple in structure and reduces the circuit design cost.

[0073] Of course, in addition to this specific structure, the temperature sensing circuit 2 can also be of other types, and the embodiment of the utility model does not limit this.

[0074] As an optional embodiment, the device protection circuit further comprises:

[0075] The prompter connected with the processor is used to prompt the temperature value and / or the on-off state of the switch chip under the control of the processor.

[0076] Specifically, considering that the staff has the need to know the situation when the PBA temperature is too high, the prompter in the embodiment of the utility model can prompt the temperature value and / or the on-off state of the switch chip under the control of the processor, and the on-off state of the switch chip means that the switch chip is in an off state when the controllable switch 3 and the photoelectric coupler 4 are turned on, so that the staff can know the situation in time and make a response.

[0077] The utility model further provides a kind of printed circuit board assembly, including the switch chip of power supply and the device protection circuit as above connected with switch chip.

[0078] For the printed circuit board assembly provided by the utility model embodiment, please refer to the foregoing embodiment of the device protection circuit, and the utility model embodiment will not be repeated here.

[0079] Each embodiment in the specification is described in a progressive manner, and each embodiment focuses on the difference from other embodiments, and the same or similar parts of each embodiment can be referred to each other.For the device disclosed by the embodiment, since it corresponds to the method disclosed by the embodiment, the description is relatively simple, and the related parts can be referred to the method part description.It should be noted that, in the specification, relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between the entities or operations.Moreover, the term "include", "contain" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or includes elements inherent to such process, method, article or device.Under no more restrictions, the element defined by the sentence "including a" does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0080] The above description of the disclosed embodiments enables a person skilled in the art to implement or use the utility model.The various modifications of these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the utility model.Therefore, the utility model will not be limited to these embodiments shown in the text, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A device protection circuit, characterized by, The device protection circuit comprises a voltage source, a temperature sensing circuit, a controllable switch and a photoelectric coupler. The voltage source is connected with the temperature sensing circuit and the input end of the photoelectric coupler respectively, the temperature sensing circuit is connected with the control end of the controllable switch, the input end of the photoelectric coupler is connected with the first end of the controllable switch, the second end of the controllable switch is grounded, and the output end of the photoelectric coupler is connected with the voltage detection pin of the switch chip of the power supply in the printed circuit board assembly and the ground respectively. The temperature sensing circuit is used for driving the controllable switch to be turned on when the sensed temperature is too high, so that the input end of the photoelectric coupler is electrified. The photoelectric coupler is used for being turned on at the output end when the input end is electrified, so that the voltage detection pin of the switch chip of the power supply in the printed circuit board assembly is grounded.

2. The device protection circuit of claim 1, wherein, The temperature sensing circuit comprises a voltage dividing resistor pair. The voltage dividing resistor pair comprises a first resistor and a thermistor connected with the first resistor in series, the first end of the voltage dividing resistor pair is connected with the voltage source, the second end of the voltage dividing resistor pair is grounded, and the connection point of the first resistor and the thermistor is connected with the control end of the controllable switch.

3. The device protection circuit of claim 2, wherein, The thermistor comprises a positive temperature coefficient thermistor. The first end of the first resistor serves as the first end of the voltage dividing resistor pair, the second end of the first resistor is connected with the first end of the thermistor, and the second end of the thermistor serves as the second end of the voltage dividing resistor pair. The controllable switch is used for being turned on when the voltage value of the control end voltage is higher than a preset threshold.

4. The device protection circuit of claim 3, wherein, The controllable switch comprises an N-channel metal-oxide-semiconductor field effect transistor.

5. The device protection circuit of claim 2, wherein, The device protection circuit further comprises a filtering circuit for filtering; The filtering circuit is connected with the output end of the photoelectric coupler in parallel.

6. The device protection circuit of claim 5, wherein, The device protection circuit further comprises a current limiting circuit for current limiting; The current limiting circuit is connected in series between the voltage source and the input end of the photoelectric coupler.

7. A device protection circuit according to any one of claims 2 to 6, characterised in that, The thermistor comprises a plurality of thermistor sub-resistors arranged at different positions of the printed circuit board assembly. The plurality of thermistor sub-resistors are connected in series.

8. The device protection circuit of claim 1, wherein, The temperature sensing circuit comprises a temperature sensor and a processor. The temperature sensor is arranged in the printed circuit board assembly, the temperature sensor and the processor are connected with the voltage source respectively, and the processor is connected with the temperature sensor. The temperature sensor is used for feeding back the detected temperature value to the processor, so that the processor drives the controllable switch to be turned on when the temperature value is too high.

9. The device protection circuit of claim 8, wherein, The device protection circuit further comprises: A prompter connected with the processor, used for prompting the temperature value and / or the on-off state of the switch chip under the control of the processor.

10. A printed circuit board assembly, characterized by A switch chip of a power supply and the device protection circuit as claimed in any one of claims 1 to 9 connected with the switch chip.

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