CN113472047B - Over-temperature protection circuit for charging interface and terminal equipment - Google Patents
Over-temperature protection circuit for charging interface and terminal equipment Download PDFInfo
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- CN113472047B CN113472047B CN202110823150.2A CN202110823150A CN113472047B CN 113472047 B CN113472047 B CN 113472047B CN 202110823150 A CN202110823150 A CN 202110823150A CN 113472047 B CN113472047 B CN 113472047B
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- 230000008859 change Effects 0.000 description 7
- 239000012634 fragment Substances 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 239000013535 sea water Substances 0.000 description 6
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00309—Overheat or overtemperature protection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/00304—Overcurrent protection
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
- H02J7/0031—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits using battery or load disconnect circuits
Abstract
The invention discloses a charging interface over-temperature protection circuit and terminal equipment, which are connected with an external charger, wherein the charging interface over-temperature protection circuit comprises an over-temperature protection module and a charging interface; the over-temperature protection module, the charging interface and the external charger are sequentially connected to form a charging loop; the over-temperature protection module is used for converting the charging temperature of the charging interface into detection voltage, controlling the charging interface to be short-circuited when the detection voltage is larger than a preset value, triggering the external charger to start short-circuit protection to cut off a charging loop, and controlling the working state of the charging interface by the over-temperature protection circuit according to the charging temperature of the charging interface, so that the electricity safety problem of the charging interface is effectively guaranteed.
Description
Technical Field
The present invention relates to the field of electronic circuits, and in particular, to a charging interface over-temperature protection circuit and a terminal device.
Background
Existing mobile terminal devices are often charged using a USB interface. When a user inserts a USB data line into an interface of a mobile terminal device, there may be some situations (for example, conductive metal fragments, seawater, etc. exist in the interface) which cause serious heating at the USB interface during charging, even the USB interface is damaged, so that the electricity use safety is not guaranteed.
There is thus a need for improvements and improvements in the art.
Disclosure of Invention
In view of the shortcomings of the prior art, the invention aims to provide an overheat protection circuit for a charging interface and terminal equipment, and the on-off of a charging loop is controlled according to the charging temperature of the charging interface, so that the electricity safety problem of the charging interface is effectively ensured.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the over-temperature protection circuit of the charging interface is connected with an external charger and comprises an over-temperature protection module and a charging interface; the over-temperature protection module, the charging interface and the external charger are sequentially connected to form a charging loop; the over-temperature protection module is used for converting the charging temperature of the charging interface into detection voltage, controlling the charging interface to be short-circuited when the detection voltage is larger than a preset value, and triggering the external charger to start short-circuit protection to cut off a charging loop.
In the charge interface over-temperature protection circuit, the over-temperature protection module comprises a temperature detection unit and a protection unit; the temperature detection unit is respectively connected with the protection unit and the charging interface, and the protection unit is also connected with the charging interface; the temperature detection unit is used for detecting the charging temperature of the charging interface, converting the charging temperature into the detection voltage and outputting the detection voltage to the protection unit; and the protection unit is used for controlling the short circuit of the charging interface when the detection voltage is larger than a preset value.
In the charge interface over-temperature protection circuit, the protection unit comprises a first switch subunit and a second switch subunit; the first switch subunit is respectively connected with the second switch subunit and the temperature detection unit, and the second switch subunit is also connected with the charging interface; the first switch subunit is used for controlling the second switch subunit to be conducted when the detection voltage is larger than the preset value; the second switch subunit is used for controlling the short circuit of the charging interface when being conducted.
In the charge interface over-temperature protection circuit, the temperature detection unit comprises a first resistor and a second resistor; one end of the first resistor is connected with one end of the second resistor and the protection unit, and the other end of the first resistor is connected with the charging interface; the other end of the second resistor is grounded.
In the charge interface over-temperature protection circuit, the first switch subunit comprises a third resistor, a fourth resistor and a first switch tube; the first end of the first switching tube is connected with the temperature detection unit, the second end of the first switching tube is connected with one end of the third resistor, and the third end of the first switching tube is connected with one end of the fourth resistor and the second switching subunit; the other end of the third resistor is connected with the temperature detection unit, the second switch subunit and the charging interface; the other end of the fourth resistor is connected with the temperature detection unit, the protection unit, the charging interface and the ground.
In the charge interface over-temperature protection circuit, the second switch subunit comprises a second switch tube; the first end of the second switching tube is connected with the first switching subunit, and the second end and the third end of the second switching tube are connected with the first switching subunit, the temperature detection unit and the charging interface.
In the interface over-temperature protection circuit charges, the interface that charges is including any one of Type A interface, mini USB interface, micro USB interface and Type C interface that charges.
In the charge interface over-temperature protection circuit, the first switching tube is a MOS tube, the first end of the first switching tube is a grid electrode of the MOS tube, the second end of the first switching tube is a drain electrode of the MOS tube, and the third end of the first switching tube is a source electrode of the MOS tube.
In the charge interface over-temperature protection circuit, the second switching tube is a MOS tube, the first end of the second switching tube is a grid electrode of the MOS tube, the second end of the second switching tube is a drain electrode of the MOS tube, and the third end of the second switching tube is a source electrode of the MOS tube.
The charging interface protection terminal device comprises a PCB board, and the charging interface over-temperature protection circuit is arranged on the PCB board.
Compared with the prior art, the over-temperature protection circuit of the charging interface and the terminal equipment provided by the invention are connected with an external charger, and the over-temperature protection circuit of the charging interface comprises an over-temperature protection module and a charging interface; the over-temperature protection module, the charging interface and the external charger are sequentially connected to form a charging loop; the over-temperature protection module is used for converting the charging temperature of the charging interface into detection voltage, controlling the charging interface to be short-circuited when the detection voltage is larger than a preset value, triggering the external charger to start short-circuit protection to cut off a charging loop, and controlling the working state of the charging interface by the over-temperature protection circuit according to the charging temperature of the charging interface, so that the electricity safety problem of the charging interface is effectively guaranteed.
Drawings
Fig. 1 is a block diagram of a charging interface over-temperature protection circuit provided by the invention;
fig. 2 is a circuit diagram of the charge interface over-temperature protection circuit provided by the invention.
Reference numerals: 10: an over-temperature protection circuit of the charging interface; 20: an external charger; 110: an over-temperature protection module; 120: a charging interface; 111, a temperature detection unit; 112: a protection unit; 1121: a first switch subunit; 1122: a second switch subunit; r1: a first resistor; r2: a second resistor; r3: a third resistor; r4: a fourth resistor; q1: a first switching tube; q2: and a second switching tube.
Detailed Description
The invention provides an over-temperature protection circuit of a charging interface and terminal equipment, which effectively ensure the electricity safety problem of the charging interface by controlling the on-off of a charging loop according to the charging temperature of the charging interface.
In order to make the objects, technical solutions and effects of the present invention clearer and more specific, the present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless expressly stated otherwise, as understood by those skilled in the art. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or wirelessly coupled. The term "and/or" as used herein includes all or any element and all combination of one or more of the associated listed items.
It will be understood by those skilled in the art that all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs unless defined otherwise. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The following describes the design scheme of the rf front-end circuit through specific exemplary embodiments, and it should be noted that the following embodiments are only used for explaining the technical scheme of the present invention, and are not limited in particular:
referring to fig. 1, a charging interface over-temperature protection circuit 10 provided by the present invention is connected to an external charger 20, wherein the charging interface over-temperature protection circuit 10 includes an over-temperature protection module 110 and a charging interface 120; the over-temperature protection module 110, the charging interface 120 and the external charger 20 are sequentially connected to form a charging loop; the over-temperature protection module 110 is configured to convert a charging temperature of the charging interface 120 into a detection voltage, and control the charging interface 120 to short when the detection voltage is greater than a preset value, so as to trigger the external charger 20 to start a short-circuit protection to cut off a charging loop.
Specifically, when the external charger 20 is connected to the charging interface 120 to perform charging, the over-temperature protection module 110 detects the charging temperature of the charging interface 120 in real time, and converts the charging temperature of the charging interface 120 into the detection voltage, if the charging interface 120 is charged with conductive metal fragments or seawater, the charging temperature of the charging interface 120 will always rise along with the longer charging time, the detection voltage converted by the over-temperature protection module 110 will also always rise, and when the detection voltage is greater than a preset value, the over-temperature protection module 110 will control the charging interface 120 to short circuit, and at this time, the external charger 20 will be triggered to start short-circuit protection, thereby cutting off the charging circuit and further effectively guaranteeing the electricity safety of the circuit.
Further, referring to fig. 1, the over-temperature protection module 110 includes a temperature detection unit 111 and a protection unit 112; the temperature detection unit 111 is respectively connected with the protection unit 112 and the charging interface 120, and the protection unit 112 is also connected with the charging interface 120; the temperature detection unit 111 is configured to detect a charging temperature of the charging interface 120, and convert the charging temperature into the detected voltage and output the detected voltage to the protection unit 112; the protection unit 112 is configured to control the charging interface 120 to be shorted when the detected voltage is greater than a preset value.
Specifically, when the external charger 20 is connected to the charging interface 120 to perform charging, the temperature detection unit 111 detects the charging temperature of the charging interface 120 in real time, converts the charging temperature of the charging interface 120 into the detection voltage, and outputs the detection voltage to the protection unit 112, if the charging interface 120 has conductive metal fragments or seawater, the charging temperature of the charging interface 120 will always rise along with the longer charging time, the detection voltage converted by the temperature detection unit 111 will also always rise, and when the detection voltage is greater than the preset value, the protection unit 112 will control the charging interface 120 to short circuit, and at this time, the external charger 20 will be triggered to start short circuit protection, thereby cutting off the charging circuit, and further effectively guaranteeing the electrical safety of the circuit; in the present invention, the temperature detection unit 111 detects the charging temperature of the charging interface 120 in real time, and converts the charging temperature into the detection voltage, so that the accurate detection voltage can be formed after the charging temperature change of the charging interface 120 is accurately detected; moreover, by setting the protection unit 112 to control the charging interface 120 to be in a short-circuit state when the detected voltage is greater than the preset value, that is, when the charging interface 120 is over-temperature, the condition for triggering the external charger 20 to start short-circuit protection is rapidly satisfied, thereby realizing a more efficient control mechanism.
Further, the protection unit 112 includes a first switch subunit 1121 and a second switch subunit 1122; the first switch subunit 1121 is connected to the second switch subunit 1122 and the temperature detecting unit 111, respectively, and the second switch subunit 1122 is further connected to the charging interface 120; the first switch subunit 1121 is configured to control the second switch subunit 1122 to be turned on when the detected voltage is greater than the preset value; the second switch subunit 1122 is configured to control the charging interface 120 to short when turned on.
Specifically, when the external charger 20 is connected to the charging interface 120 to perform charging, the temperature detection unit 111 detects the charging temperature of the charging interface 120 in real time, converts the charging temperature of the charging interface 120 into the detection voltage, and outputs the detection voltage to the first switching subunit 1121, if the charging interface 120 has conductive metal fragments or seawater, etc., the charging temperature of the charging interface 120 will always increase along with the longer charging time, the detection voltage converted by the temperature detection unit 111 will also always increase, when the first switching subunit 1121 is turned on preferentially, and when the detection voltage is greater than a preset value, the first switching subunit 1121 controls the second switching subunit 1122 to be turned on, and the second switching subunit 1122 controls the charging interface 120 to be short-circuited, and at this time, the external charger 20 is triggered to start short-circuit protection, thereby effectively guaranteeing the power safety of the circuit; in the present invention, when the detected voltage is greater than the preset value, the first switch subunit 1121 controls the second switch subunit 1122 to be turned on by setting the first switch subunit 1121 and the second switch subunit 1122, so that the second switch subunit 1122 controls the charging interface 120 to be capable of quickly entering a short-circuit state, and a more efficient control mechanism is realized.
Further, referring to fig. 2, the temperature detecting unit 111 includes a first resistor R1 and a second resistor R2; one end of the first resistor R1 is connected with one end of the second resistor R2 and the first switch subunit 1121, and the other end of the first resistor R1 is connected with the charging interface 120; the other end of the second resistor R2 is connected to the charging interface 120, the protection unit 112, and ground.
In this embodiment, the first resistor R1 is an NTC thermistor, and the characteristics of the NTC thermistor are as follows: the higher the temperature of the resistor, the lower its resistance; it should be noted that, in this embodiment, the second resistor may be a common resistor or a PTC thermistor, and the characteristics of the PTC thermistor are as follows: the higher the temperature of the resistor, the higher the resistance value; specifically, when the external charger 20 is connected to the charging interface 120 to perform charging, firstly, the first resistor R1 detects the charging temperature of the charging interface 120 in real time, and changes its resistance value in real time according to the charging temperature, the voltage dividing circuit formed by the first resistor R1 and the second resistor R2 divides the voltages at two ends of the charging interface 120 to obtain divided voltages, that is, the voltages at two ends of the second resistor R2, that is, the detected voltages, and outputs the detected voltages to the first switch subunit 1121, and secondly, the first switch subunit 1121 processes the detected voltages and then transmits the processed voltages to the second switch subunit 1122; if there are conductive metal fragments, seawater, etc. in the charging interface 120, as the charging time becomes longer, the charging temperature of the charging interface 120 will always increase, the resistance value of the first resistor R1 will always decrease, and the detection voltage will always increase; when the detected voltage is greater than a preset value, the first switch subunit 1121 controls the second switch subunit 1122 to be turned on, and the second switch subunit 1122 controls the charging interface 120 to be short-circuited, and at this time, the external charger 20 is triggered to start short-circuit protection, so as to cut off the charging circuit, thereby effectively guaranteeing the electricity safety of the circuit. In the present invention, the first resistor R1 is set as an NTC thermistor, and is used for detecting the charging temperature of the charging interface 120 in real time, and since the NTC thermistor is located adjacent to the charging interface 120, the change of the charging temperature can be detected quickly, so that the second switch subunit 1122 can act quickly when it is over-temperature, so as to realize quick cutting off of the circuit loop.
Further, the first switching subunit 1121 includes a third resistor R3, a fourth resistor R4, and a first switching tube Q1; a first end of the first switching tube Q1 is connected to one end of the first resistor R1 and one end of the second resistor R2, a second end of the first switching tube Q1 is connected to one end of the third resistor R3, and a third end of the first switching tube Q1 is connected to one end of the fourth resistor R4 and the second switching subunit 1122; the other end of the third resistor R3 is connected to the charging interface 120; the other end of the fourth resistor R4 is grounded.
Specifically, when the external charger 20 is charged by the charging interface 120, the charging temperature of the charging interface 120 is always increased, and when the charging temperature of the charging interface 120 has an over-temperature phenomenon, the voltage divided voltage converted by the voltage dividing circuit formed by the first resistor R1 and the second resistor R2 is continuously increased, that is, the detection voltage converted by the charging temperature of the charging interface 120 is continuously increased; because the detection voltage is directly transmitted to the first end of the first switching tube Q1 by the voltage dividing circuit, when the detection voltage is greater than the conducting voltage of the first switching tube Q1, that is, the detection voltage is greater than a preset value, the first switching tube Q1 is conducted; because the third resistor R3, the fourth resistor R4 and the first switching tube Q1 together form an amplifying circuit, the detection voltage is amplified by the amplifying circuit and then output to the second switching subunit 1122, that is, output to the second switching subunit 1122 through the third end of the first switching tube Q1; at this time, the second switch subunit 1122 is also turned on, so that the charging interface 120 is directly shorted, and the external charger 20 is triggered to start the short-circuit protection, so as to cut off the charging circuit, thereby effectively guaranteeing the electricity safety of the circuit. In the invention, the first switching tube Q1 corresponds to a switch, when the charging temperature changes to a certain value, the voltage value of the first resistor R1 also changes to a certain extent, the input voltage of the first switching tube Q1 also changes accordingly, and only when the input voltage of the first switching tube Q1 is greater than the on voltage of the switching tube, the first switching tube Q1 is turned on, thereby effectively realizing the change of the opening and closing state of the first switching tube Q1 according to the change of the charging temperature. The third resistor R3, the fourth resistor R4 and the first switching tube Q1 together form a common drain amplifying circuit, so that the detection voltage can be increased and output to the second switching subunit 1122, and the second unit can act faster.
Further, the second switching sub-unit 1122 includes a second switching tube Q2; a first end of the second switching tube Q2 is connected to the third end of the first switching subunit 1121 and one end of the fourth resistor, and a second end of the second switching tube Q2 is connected to the charging interface 120; the third end of the second switching tube Q2 is grounded.
Specifically, after the first switching tube Q1 is turned on, the first switching tube Q1 transmits the amplified detection voltage to the first end of the second switching tube Q2, and when the amplified detection voltage is greater than the turn-on voltage of the second switching tube Q2, the second switching tube Q2 is also turned on, so as to control the charging interface 120 to be directly shorted, and thus the external charger 20 is triggered to start short-circuit protection, so that the charging loop is cut off, and the electricity safety of the circuit is effectively ensured. Similarly, in the present invention, the second switching tube Q2 is also equivalent to a switch, and only when the voltage value of the first resistor R1 changes to a certain value along with the charging temperature, that is, when the divided voltage outputted by the voltage dividing circuit also changes to a certain value along with the charging temperature, that is, when the detected voltage also changes to a certain value along with the charging temperature, and when the detected voltage is greater than a preset value, that is, when the input voltage of the first switching tube Q1 is greater than the on voltage of the switching tube, the second switching tube Q2 is turned on immediately, so that the switching state of the first switching tube Q1 is effectively changed according to the change of the charging temperature, and the switching state of the second switching tube Q2 is further changed.
Further, the charging interface 120 is any one of the charging interfaces 120 including a Type a interface, a Mini USB interface, a Micro USB interface, and a Type C interface.
Specifically, the VUBS port and the GND port of the charging interface 120 are respectively used as the positive and negative poles of the circuit to be connected into the circuit, and the Shell port of the charging interface 120 and the GND port of the charging interface 120 are both grounded. When the second unit is turned on, the VUBS port and the GND port of the charging interface 120 are directly connected to cause a short circuit, and the external charger 20 is triggered to start the short circuit protection, so as to cut off the charging circuit, and further effectively ensure the electricity safety of the circuit.
Further, the first switching tube Q1 is a MOS tube, a first end of the first switching tube Q1 is a gate of the MOS tube, a second end of the first switching tube Q1 is a drain of the MOS tube, and a third end of the first switching tube Q1 is a source of the MOS tube.
Specifically, the first switching tube Q1 is an N-channel MOS tube, when the input voltage (Vgs) of the gate of the MOS tube is greater than the turn-on voltage (Vtn, generally +2v) of the MOS tube, that is, the divided voltage is greater than the turn-on voltage of the first switching tube Q1, the first switching tube Q1 is turned on, and then the amplifying circuit formed by the first switching tube Q1, the third resistor R3 and the fourth resistor R4 amplifies the detection voltage and then transmits the amplified detection voltage to the second switching tube Q2, so as to perform the next operation.
Further, the second switching tube Q2 is a MOS tube, the first end of the second switching tube Q2 is a gate of the MOS tube, the second end of the second switching tube Q2 is a drain of the MOS tube, and the third end of the second switching tube Q2 is a source of the MOS tube.
Specifically, after the first switching tube Q1 is turned on, the common drain amplifying circuit formed by the first switching tube Q1, the third resistor R3 and the fourth resistor R4 amplifies the detection voltage and outputs the amplified detection voltage to the gate of the second switching tube Q2, and similarly, the second switching tube Q2 is an N-channel MOS tube, when the input voltage of the gate of the MOS tube is greater than the turn-on voltage of the MOS tube, that is, the detection voltage is greater than the turn-on voltage of the second switching tube Q2, the second switching tube Q2 is turned on, and the VUBS port and the GND port of the charging interface 120 are directly connected to cause a short circuit, at this time, the external charger 20 is triggered to start a short circuit protection, thereby cutting off the charging circuit and further effectively guaranteeing the electricity use safety of the circuit. The first switch tube Q1, the third resistor R3 and the fourth resistor R4 together form a common drain amplifying circuit, so that the second switch tube Q2 can be rapidly switched between a saturation region and an interception region, and the effect that the second switch tube Q2 can be rapidly conducted or closed is achieved.
It should be noted that, in this embodiment, the first switching transistor and the second switching transistor may also be sampling transistors, where the second switching transistor may also be a push-pull circuit, which is not limited in detail by the present invention.
For a better understanding of the present invention, the following describes the working principle of the charge interface over-temperature protection circuit 10 according to the present invention in detail with reference to fig. 1 and 2:
when the external charger 20 is connected to the charging interface 120 to perform charging, the first resistor R1, that is, the NTC thermistor detects the charging temperature of the charging interface 120 in real time and changes its own resistance value in real time according to the charging temperature, and since the NTC thermistor is located adjacent to the charging interface 120, it is able to quickly change its own resistance value according to the change of the charging temperature;
if the charging interface 120 is normally charged, that is, if no over-temperature phenomenon occurs, at this time, the charging temperature is normal, according to the characteristics of the NTC thermistor: the higher the temperature of the resistor, the lower its resistance, so the resistance of the NTC thermistor is greater at this time; furthermore, since the NTC thermistor and the second resistor R2 form a voltage dividing circuit, the voltage dividing circuit divides the voltages at two ends of the charging interface 120 to form a divided voltage, that is, the voltages at two ends of the second resistor R2, that is, the detection voltage, and transmits the detected voltage to the first end of the first switching tube Q1 as the input voltage of the first switching tube Q1; however, since the resistance of the NTC thermistor is larger at this time, the voltage across the second resistor R2 obtained by the voltage dividing circuit is smaller, that is, the input voltage of the first switching tube Q1 is smaller, that is, the detected voltage is smaller than the preset value at this time, the first switching tube Q1 cannot be turned on, at this time, the second switching tube Q2 cannot be turned on, and the external charger 20 performs normal charging;
if there are conductive metal fragments or seawater and the like in the charging interface 120, as the charging time increases, the charging temperature of the charging interface 120 will always increase, when the charging temperature reaches a certain value, i.e. when an overtemperature phenomenon occurs, at this time, the self resistance of the NTC thermistor will continuously decrease, and as the resistance of the NTC thermistor continuously decreases, the voltage at both ends of the second resistor R2 continuously increases correspondingly, i.e. the input voltage of the first switching tube Q1 continuously increases correspondingly, i.e. the detection voltage continuously increases correspondingly; then, when the input voltage of the first switching tube Q1 is greater than the turn-on voltage of the first switching tube Q1, that is, the detection voltage is greater than a preset value, the first switching tube Q1 is turned on, and the detection voltage is amplified by a common drain amplifying circuit formed by the first switching tube Q1, the third resistor R3 and the fourth resistor R4 together, and the first switching tube Q1 transmits the detection voltage to the second switching tube Q2; when the detected voltage is greater than the on voltage of the second switching tube Q2, the second switching tube Q2 is also turned on, and the VUBS port and the GND port of the charging interface 120 are directly connected to cause a short circuit, so that the external charger 20 is triggered to start the short circuit protection, thereby cutting off the charging circuit and further effectively guaranteeing the electricity safety of the circuit.
According to the invention, the charging temperature at the charging interface is detected in real time through the thermistor, when the charging temperature is over-temperature, the thermistor changes the voltage at two ends of the thermistor by changing the resistance value of the thermistor, so that the input voltage of the switching tube is changed, and when the switching tube in the circuit is conducted, two ports of the charging interface are directly short-circuited, so that an external charger is triggered to start a short-circuit protection function, so that a charging loop is cut off, and the electricity utilization safety of the circuit is effectively ensured; in addition, the invention can realize the effects by using one thermistor, two N-channel MOS tubes and three fixed-value resistors and can effectively save the design cost of the circuit.
Further, the present invention also provides a terminal device, which includes a PCB board, and the PCB board is provided with the above-mentioned charging interface over-temperature protection circuit 10, and since the above description of the circuit is detailed, the detailed description is omitted here.
In summary, the over-temperature protection circuit and the terminal device for the charging interface provided by the invention are connected with an external charger, and the over-temperature protection circuit for the charging interface comprises an over-temperature protection module and the charging interface; the over-temperature protection module, the charging interface and the external charger are sequentially connected to form a charging loop; the over-temperature protection module is used for converting the charging temperature of the charging interface into detection voltage, controlling the charging interface to be short-circuited when the detection voltage is larger than a preset value, triggering the external charger to start short-circuit protection to cut off a charging loop, and controlling the working state of the charging interface by the over-temperature protection circuit according to the charging temperature of the charging interface, so that the electricity safety problem of the charging interface is effectively guaranteed.
It will be understood that equivalents and modifications will occur to those skilled in the art in light of the present invention and their spirit, and all such modifications and substitutions are intended to be included within the scope of the present invention as defined in the following claims.
Claims (8)
1. The over-temperature protection circuit of the charging interface is connected with an external charger and is characterized by comprising an over-temperature protection module and a charging interface; the over-temperature protection module, the charging interface and the external charger are sequentially connected to form a charging loop; the over-temperature protection module is used for converting the charging temperature of the charging interface into detection voltage, controlling the charging interface to be short-circuited when the detection voltage is larger than a preset value, and triggering the external charger to start short-circuit protection to cut off a charging loop;
the over-temperature protection module comprises a temperature detection unit and a protection unit; the temperature detection unit is respectively connected with the protection unit and the charging interface, and the protection unit is also connected with the charging interface; the temperature detection unit is used for detecting the charging temperature of the charging interface, converting the charging temperature into the detection voltage and outputting the detection voltage to the protection unit; the protection unit is used for controlling the short circuit of the charging interface when the detection voltage is larger than a preset value;
the protection unit comprises a first switch subunit and a second switch subunit; the first switch subunit is respectively connected with the second switch subunit and the temperature detection unit, and the second switch subunit is also connected with the charging interface; the first switch subunit is used for controlling the second switch subunit to be conducted when the detection voltage is larger than the preset value; the second switch subunit is used for controlling the short circuit of the charging interface when being conducted;
when the detection voltage is larger than the preset value, the first switch subunit controls the second switch subunit to be conducted, so that the second switch subunit controls the charging interface to enter a short circuit state rapidly.
2. The charge interface overtemperature protection circuit of claim 1, wherein said temperature detection unit comprises a first resistor and a second resistor; one end of the first resistor is connected with one end of the second resistor and the protection unit, and the other end of the first resistor is connected with the charging interface; the other end of the second resistor is grounded.
3. The charge interface over-temperature protection circuit of claim 1, wherein the first switch subunit comprises a third resistor, a fourth resistor, and a first switching tube; the first end of the first switching tube is connected with the temperature detection unit, the second end of the first switching tube is connected with one end of the third resistor, and the third end of the first switching tube is connected with one end of the fourth resistor and the second switching subunit; the other end of the third resistor is connected with the charging interface; the other end of the fourth resistor is grounded.
4. The charge interface over-temperature protection circuit of claim 1, wherein the second switch subunit comprises a second switch tube; the first end of the second switching tube is connected with the first switching subunit, the second end of the second switching tube is connected with the charging interface, and the third end of the second switching tube is grounded.
5. The charge interface overtemperature protection circuit of any of claims 1-4, wherein the charge interface is any of charge interfaces including a Type a interface, a Mini USB interface, a Micro USB interface, and a Type C interface.
6. The charge interface over-temperature protection circuit of claim 3, wherein the first switching tube is a MOS tube, a first end of the first switching tube is a gate of the MOS tube, a second end of the first switching tube is a drain of the MOS tube, and a third end of the first switching tube is a source of the MOS tube.
7. The charge interface over-temperature protection circuit of claim 4, wherein the second switching tube is a MOS tube, a first end of the second switching tube is a gate of the MOS tube, a second end of the second switching tube is a drain of the MOS tube, and a third end of the second switching tube is a source of the MOS tube.
8. A terminal device comprising a PCB board, wherein the PCB board is provided with the charge interface overtemperature protection circuit according to any one of claims 1-7.
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