Protection circuit and wireless earphone charging bin

Abstract

The utility model discloses a protection circuit and a wireless earphone charging cabin, and relates to the technical field of wireless earphones. The protection circuit comprises a thermistor, a first resistor, a second resistor, a first switch tube and a second switch tube. The charging seat of the wireless earphone charging bin comprises a charging seat circuit, and the thermistor can detect the temperature of the charging seat and control the turn-off and turn-on of the first switch tube according to the temperature of the charging seat so as to control the turn-on and turn-off of the second switch tube. When the temperature of the charging seat reaches the anti-scald temperature, the second switch tube is conducted to trigger the short circuit of the charging seat circuit, so that the short circuit protection of the charging adapter is triggered, the charging output is cut off, and the aim of preventing the human body from being scalded due to contact is fulfilled. According to the utility model, the anti-scald purpose can be achieved through the pure hardware circuit design, the software algorithm control of the control chip is not needed, the I / O port resource is saved, and the cost is saved.

Description

Technical Field

[0001] The utility model relates to the technical field of wireless earphones, and particularly relates to a protection circuit and a charging bin for wireless earphones. Background Art

[0002] With the improvement of people's living standards, wireless earphones such as TWS (True-Wireless-Stereo) earphones and OWS (Open-Wearable-Stereo) earphones are becoming more and more popular among people due to their convenience. Among them, the wireless earphones are charged through a charging bin for wireless earphones and are externally connected to a charging adapter through a charging base.

[0003] At present, there are two ways to protect the charging over-temperature of the charging bin for wireless earphones. One is to add a temperature detection circuit, and the control chip adjusts the charging current according to the temperature change to prevent overheating, but this method will consume the I / O port resources of the control chip; the other is to use a charging base made of high-temperature resistant material, but when the temperature of the charging base is too high, it is easy to scald the contacting human body. Summary of the Utility Model

[0004] The main purpose of the utility model is to provide a protection circuit, aiming to realize charging over-temperature protection in the way of a hardware circuit and prevent the charging base from scalding the contacting human body due to too high temperature.

[0005] To achieve the above purpose, the protection circuit proposed by the utility model is applied to a charging bin for wireless earphones; the protection circuit includes a thermistor, a first resistor, a second resistor, a first switching tube and a second switching tube;

[0006] Wherein, one end of the first resistor, one end of the second resistor, the first end of the second switching tube are circuit-connected to the charging base of the charging bin for wireless earphones; the other end of the first resistor, one end of the thermistor are connected to the controlled end of the first switching tube; the other end of the second resistor, the first end of the first switching tube are connected to the controlled end of the second switching tube; the other end of the thermistor, the second end of the first switching tube and the second end of the second switching tube are grounded.

[0007] In one embodiment, the thermistor is a negative temperature coefficient thermistor.

[0008] In one embodiment, the first switching tube is a switching triode, the base of the switching triode is connected to one end of the thermistor, the collector of the switching triode is connected to the controlled end of the second switching tube, and the emitter of the switching triode is grounded.

[0009] In one embodiment, the second switching transistor is an NMOS transistor. The gate of the NMOS transistor is connected to the first end of the first switching transistor. The drain of the NMOS transistor is connected to the charging base circuit, and the source of the NMOS transistor is grounded.

[0010] In one embodiment, the protection circuit further includes a first capacitor. One end of the first capacitor is connected to one end of the first resistor, and the other end of the first capacitor is grounded.

[0011] In one embodiment, the protection circuit further includes a second capacitor. One end of the second capacitor is connected to one end of the thermistor, and the other end of the second capacitor is grounded.

[0012] In one embodiment, the first resistor is a variable resistor.

[0013] In one embodiment, the model of the negative temperature coefficient thermistor is SDNT1005X103.

[0014] The present utility model further provides a wireless earphone charging case, and the wireless earphone charging case includes the protection circuit as described above.

[0015] In one embodiment, the wireless earphone charging case further includes a charging base circuit, a power supply circuit, a battery, a control circuit and a wireless communication circuit;

[0016] Wherein, the input end of the charging base circuit is used to connect a charging adapter, and the output end of the charging base circuit is respectively connected to the input ends of the protection circuit and the power supply circuit; the output end of the power supply circuit is connected to the battery; the control circuit is respectively connected to the power supply circuit and the wireless communication circuit.

[0017] The technical solution of the present utility model adopts a protection circuit, which is applied to a wireless earphone charging case. The protection circuit includes a thermistor, a first resistor, a second resistor, a first switching tube and a second switching tube. Among them, the charging base of the wireless earphone charging case includes a charging base circuit. The thermistor can detect the temperature of the charging base and control the cut-off and conduction of the first switching tube according to the temperature of the charging base, so as to control the conduction and cut-off of the second switching tube. The first resistor can be used for voltage division of the output voltage of the charging base circuit, and the second resistor can be used for current limiting to protect the normal operation of the first switching tube and the second switching tube. The resistance value of the first resistor can be determined and set by the selected anti-scalding temperature and the resistance value of the thermistor at the anti-scalding temperature. When the temperature of the charging base reaches the anti-scalding temperature, the second switching tube conducts, triggering a short circuit of the charging base circuit, thereby triggering the short circuit protection of the charging adapter, so as to cut off the charging output and achieve the purpose of preventing human contact from being scalded. The present utility model can achieve the purpose of anti-scalding through a pure hardware circuit design, and does not require the software algorithm control of a control chip, saving I / O port resources and cost. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0019] Figure 1 It is the electronic circuit diagram of an embodiment of the protection circuit provided by the present utility model;

[0020] Figure 2 It is the electronic circuit diagram of another embodiment of the protection circuit provided by the present utility model;

[0021] Figure 3 It is the schematic structural diagram of an embodiment of the wireless earphone charging case provided by the present utility model.

[0022] Explanation of the reference numerals in the drawings:

[0023]

[0024] The realization, functional features and advantages of the object of the present utility model will be further described with reference to the embodiments and the drawings. Detailed Embodiment

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0026] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0027] In addition, the descriptions involving "first", "second", etc. in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0028] In the prior art, there are two ways to protect against overheating during charging of a wireless earphone charging case. One is to add a temperature detection circuit, and the control chip (such as an MCU chip) adjusts the charging current according to the temperature change to prevent overheating, but this method will consume the I / O port resources of the control chip; the other is to use a charging base made of high-temperature resistant material, but when the temperature of the charging base is too high, it is easy to scald the contacting human body.

[0029] To solve the above problems, the present invention proposes a protection circuit 01.

[0030] Please refer to Figure 1 , in an embodiment of the present invention, the protection circuit 01 is applied to a wireless earphone charging case; the protection circuit 01 includes a thermistor RT, a first resistor R1, a second resistor R2, a first switching tube Q1, and a second switching tube Q2;

[0031] One end of the first resistor R1, one end of the second resistor R2, and the first end of the second switching transistor Q2 are connected to the charging base circuit 02 of the wireless earphone charging case; the other end of the first resistor R1 and one end of the thermistor RT are connected to the controlled end of the first switching transistor Q1; the other end of the second resistor R2 and the first end of the first switching transistor Q1 are connected to the controlled end of the second switching transistor Q2; the other end of the thermistor RT and the second end of the first switching transistor Q1 are grounded together with the second end of the second switching transistor Q2.

[0032] It should be noted that the charging adapter of the wireless earphone charging case includes a short-circuit protection module. When a short circuit is detected in the circuit, the short-circuit protection module can activate the short-circuit protection mechanism to control the disconnection of the charging connection of the wireless earphone charging case.

[0033] It should be noted that the charging base inside the wireless earphone charging case includes a charging base circuit 02. The charging base circuit 02 is used to identify the charging protocol with the charging adapter and transmit the output power of the charging adapter to the power supply circuit of the wireless earphone charging case. The thermistor RT can be arranged close to the charging base to detect the temperature change of the charging base.

[0034] In this embodiment, the first resistor R1 can be used to divide the voltage VBUS_IN output by the charging base circuit 02 of the wireless earphone charging case. The second resistor R2 can play a role in current limiting to protect the normal operation of the first switching transistor Q1 and the second switching transistor Q2. The resistance value of the first resistor R1 can be determined and set according to the selected anti-scalding temperature and the resistance value of the thermistor RT at the anti-scalding temperature. The thermistor RT can detect the temperature of the charging base and control the cut-off and conduction of the first switching transistor Q1 according to the temperature of the charging base, so as to control the conduction and cut-off of the second switching transistor Q2. When the temperature of the charging base reaches the anti-scalding temperature, the second switching transistor Q2 conducts, triggering a short circuit in the charging base circuit 02, thereby triggering the short-circuit protection of the charging adapter, cutting off the charging output, pausing the charging, and achieving the purpose of preventing the temperature of the charging base from rising continuously and avoiding scalding when the human body touches the charging base.

[0035] In this embodiment, the thermistor RT can be a positive temperature coefficient thermistor or a negative temperature coefficient thermistor. The first switching tube Q1 can be a triode, a MOS tube, or an IGBT tube. The second switching tube Q2 can be a triode, a MOS tube, or an IGBT tube. For example, in this embodiment, the thermistor RT can be a negative temperature coefficient resistor (NTC resistor, Negative Temperature Coefficient Thermistor), the first switching tube Q1 can be an NPN triode, and the second switching tube Q2 can be an NMOS tube. Then, when the NTC resistor detects that the temperature of the charging base of the wireless earphone charging case has not reached the preset temperature, the resistance value of the NTC resistor is relatively high, the base voltage of the NPN triode is higher than the threshold voltage, the NPN triode is in the conducting state, and the NMOS tube is in the cut-off state. The charging base circuit 02 can normally transmit the charging power supply. As the temperature of the charging base of the wireless earphone charging case rises, the resistance value of the NTC resistor decreases, and the base voltage of the NPN triode also decreases. Until the temperature of the charging base of the wireless earphone charging case rises to the anti-scalding temperature, the base voltage of the NPN triode drops to the threshold voltage, then the NPN triode switches from the conducting state to the cut-off state, and the NMOS tube switches to the conducting state. Then, the output end of the charging base circuit 02 of the wireless earphone charging case is grounded, resulting in a short circuit, triggering the short-circuit protection mechanism of the charging adapter, and controlling the cut-off of the output of the charging power supply of the charging base circuit 02. In this way, in this embodiment, the action of the first switching tube Q1 is triggered by the thermistor RT, thereby triggering the action of the second switching tube Q2, and the stability of the circuit control is relatively high. In this way, this embodiment can play a role in overheat protection for the charging base of the wireless earphone charging case, preventing the temperature of the charging base from being too high and scalding the contacting human body. This embodiment does not require software algorithm control of the control chip, saving I / O port resources and cost.

[0036] In the present utility model, the charging base of the wireless earphone charging case includes a charging base circuit 02. The thermistor RT can detect the temperature of the charging base and control the cut-off and conduction of the first switching tube Q1 according to the temperature of the charging base, thereby controlling the conduction and cut-off of the second switching tube Q2. The first resistor R1 can be used for voltage division of the output voltage of the charging base circuit, and the second resistor R2 can be used for current limiting to protect the normal operation of the first switching tube Q1 and the second switching tube Q2. The resistance value of the first resistor R1 can be determined and set by the selected anti-scalding temperature and the resistance value of the thermistor RT at the anti-scalding temperature. When the temperature of the charging base reaches the anti-scalding temperature, the second switching tube Q2 conducts, triggering a short circuit in the charging base circuit 02, thereby triggering the short-circuit protection of the charging adapter, and thus cutting off the charging output, achieving the purpose of preventing the human body from being scalded by contact. The present utility model can achieve the purpose of anti-scalding through a pure hardware circuit design, and does not require software algorithm control of the control chip, saving I / O port resources and cost.

[0037] In an embodiment of the present utility model, the thermistor RT is a negative temperature coefficient thermistor.

[0038] In this embodiment, the negative temperature coefficient thermistor (NTC resistor), that is, the thermistor whose resistance value decreases as the temperature increases, has a relatively sensitive temperature change response and can quickly capture the temperature change, so as to quickly trigger the action of the first switching tube Q1 when the charging base reaches the anti-scalding temperature.

[0039] In an embodiment of the present utility model, the first switching tube Q1 is a switching triode. The base of the switching triode is connected to one end of the thermistor RT, the collector of the switching triode is connected to the controlled end of the second switching tube Q2, and the emitter of the switching triode is grounded.

[0040] In this embodiment, the driving method of the switching triode is relatively simple and the cost is relatively low. When the voltage across the thermistor RT is higher than the threshold voltage, the switching triode is in the conducting state; when the voltage across the thermistor RT decreases below the threshold voltage, the switching triode changes from the conducting state to the cut-off state. In this embodiment, the switching triode can be an NPN triode.

[0041] In an embodiment of the present utility model, the second switching tube Q2 is an NMOS transistor. The gate of the NMOS transistor is connected to the first end of the first switching tube Q1, the drain of the NMOS transistor is connected to the charging base circuit 02, and the source of the NMOS transistor is grounded.

[0042] In this embodiment, the NMOS transistor can be controlled by a low voltage and is suitable for portable devices such as wireless earphone charging cases. When the switching triode is in the conducting state, the NMOS transistor is in the cut-off state, and the charging base circuit 02 can normally transmit the charging power supply; when the switching triode is in the cut-off state, the NMOS transistor is in the conducting state, and the output of the charging power supply of the charging base circuit 02 is cut off.

[0043] Please refer to Figure 2 , in an embodiment of the present utility model, the protection circuit 01 further includes a first capacitor C1. One end of the first capacitor C1 is connected to one end of the first resistor R1, and the other end of the first capacitor C1 is grounded.

[0044] In this embodiment, the first capacitor C1 can filter out interference on the voltage at the controlled end of the second switching tube Q2, specifically filter out the AC signal, so that the controlled end of the second switching tube Q2 accurately receives the DC signal, ensuring the normal conduction / cut-off of the second switching tube.

[0045] Please refer to Figure 2, in an embodiment of the present utility model, the protection circuit 01 further includes a second capacitor C2. One end of the second capacitor C2 is connected to one end of the thermistor RT, and the other end of the second capacitor C2 is grounded.

[0046] In this embodiment, the second capacitor C2 can perform interference filtering on the voltage at the controlled end of the first switching transistor Q1. Specifically, it can filter out the AC signal, so that the controlled end of the first switching transistor Q1 accurately receives the DC signal, ensuring the normal conduction / cutoff of the first switching transistor.

[0047] Please refer to Figure 2 , in an embodiment of the present utility model, the first resistor R1 is a variable resistor.

[0048] In this embodiment, the resistance value of the first resistor R1 can be adjusted according to the set anti-scalding temperature, so that the second switching transistor Q2 conducts and is grounded when the protection circuit reaches the anti-scalding temperature. For example, when the anti-scalding temperature is set to 70 °C, the resistance value of the first resistor R1 can be adjusted to 16.2 KΩ. Assume that the output voltage of the charging base circuit 02 is 5V, and the resistance value of the NTC resistor at 25 °C is 10 KΩ. When the temperature of the charging base reaches 60 °C, at this time the resistance value of the NTC resistor is 3 KΩ, then the voltage division at the base of the switching triode is 3 KΩ / (3 KΩ + 16.2 KΩ) * 5V, approximately 0.78V, then the switching triode conducts, and the NMOS transistor is cut off. At this time, the temperature of the charging base has not reached the anti-scalding temperature, and the charging power supply can be normally input. When the temperature of the charging base reaches 70 °C, due to the increase in temperature, the resistance value of the NTC resistor decreases, then the voltage division of the NTC resistor decreases. At this time, the resistance value of the NTC resistor is 2.21 KΩ, then the voltage division at the base of the switching triode is 2.21 KΩ / (2.21 KΩ + 16.2 KΩ) * 5V, approximately 0.6V, then the switching triode changes from conduction to cutoff, and the NMOS transistor conducts and is grounded, triggering the short-circuit protection mechanism of the charging adapter to control the charging to stop. At this time, the temperature of the charging base reaches the anti-scalding temperature, the input of the charging power supply stops, and the temperature of the charging base stops rising. In this way, this embodiment can adjust the resistance value of the first resistor R1 according to the set anti-scalding temperature, the output voltage of the charging base circuit 02, and the temperature parameter of the NTC resistor. For example, for an NTC resistor with a resistance value of 10 KΩ at the standard temperature of 25 °C, the resistance values at 40 °C, 50 °C, 60 °C, 65 °C, 70 °C, and 80 °C are 5.8 KΩ, 4.13 KΩ, 3 KΩ, 2.57 KΩ, 2.21 KΩ, and 1.66 KΩ respectively. Then, when the anti-scalding temperatures are set to 40 °C, 50 °C, 60 °C, 65 °C, 70 °C, or 80 °C respectively, the first resistor R1 can be adjusted to 42.5 KΩ, 30 KΩ, 22 KΩ, 18.9 KΩ, 16.2 KΩ, or 12.2 KΩ respectively.

[0049] In an embodiment of the present utility model, the model of the negative temperature coefficient thermistor is SDNT1005X103.

[0050] In this embodiment, the NTC resistor of the model SDNT1005X103 has the advantages of high sensitivity, fast response, small volume, and low cost. It is suitable for detecting the temperature of the charging base, and its resistance value decreases when the temperature rises, so that the input power supply of the charging base circuit 02 can be cut off when the circuit reaches the anti-scalding temperature, and it is suitable for the temperature detection of the wireless earphone charging case.

[0051] The present utility model also proposes a wireless earphone charging case, which includes a protection circuit 01. The specific structure of the protection circuit 01 refers to the above embodiment. Since this wireless earphone charging case adopts all the technical solutions of the above all embodiments, it at least has all the beneficial effects brought by the technical solutions of the above embodiments, and will not be elaborated herein one by one.

[0052] Please refer to Figure 3 , in an embodiment of the present utility model, the wireless earphone charging case further includes a charging base circuit 02, a power supply circuit 03, a battery 04, a control circuit 05, and a wireless communication circuit 06;

[0053] Among them, the input end of the charging base circuit 02 is used to connect a charging adapter, and the output end of the charging base circuit 02 is respectively connected to the input end of the protection circuit 01 and the power supply circuit 03; the output end of the power supply circuit 03 is connected to the battery 04; the control circuit 05 is respectively connected to the power supply circuit 03 and the wireless communication circuit 06.

[0054] In this embodiment, the charging base is a TYPE-C charging base. The charging base circuit 02 is used for charging protocol identification. The power supply circuit 03 may include a DC-DC converter, a lithium battery 04 protection circuit 01, and an LDO (Low Drop-Out Regulator) voltage regulator. The battery 04 may be a lithium-ion battery 04, and the control circuit 05 may include an MCU chip. The wireless communication circuit 06 may include a Bluetooth chip.

[0055] In this embodiment, when the wireless earphone charging case is being charged, the charging base circuit 02 and the charging adapter can identify the charging protocol. When the charging base circuit 02 and the charging adapter can be correctly matched, the charging adapter can convert the external power supply voltage and transmit it to the power supply circuit 03 through the charging base circuit 02 after voltage conversion. The power supply circuit 03 can convert the power output by the charging base circuit 02 into the charging power for the battery 04, such as performing operations such as boosting, bucking, or voltage regulation, and can manage the charging state of the battery 04. The control circuit 05 is respectively connected to the power supply circuit 03 and the wireless communication circuit 06, and can control the operation of the power supply circuit 03 and the wireless communication circuit 06. The control circuit 05 can perform data communication with external devices such as mobile phones, tablets, or computers through the wireless communication circuit 06, and transmit information such as the charging progress, battery power level, and connection status to the external devices. Among them, during the charging process, the protection circuit 01 can detect the temperature of the charging base. When the temperature of the charging base reaches the anti-scalding temperature, the output end of the charging base circuit 02 is grounded, thereby triggering the short-circuit protection of the charging adapter, cutting off the charging output, pausing the charging, so as to prevent the temperature of the charging base from rising continuously and avoid the occurrence of scalding accidents when the human body touches it.

[0056] The above are only exemplary embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. All equivalent structural transformations made under the technical concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A protection circuit, characterized in that: The protection circuit is applied to a wireless headset charging compartment; the protection circuit comprises a thermistor, a first resistor, a second resistor, a first switch tube and a second switch tube; Among them, one end of the first resistor, one end of the second resistor, and a first end of the second switch tube are connected to the charging base circuit of the wireless headset charging case; the other end of the first resistor and one end of the thermistor are connected to the controlled end of the first switch tube; the other end of the second resistor and the first end of the first switch tube are connected to the controlled end of the second switch tube; the other end of the thermistor, the second end of the first switch tube, and the second end of the second switch tube are grounded.

2. The protection circuit according to claim 1, characterized in that: The thermistor is a negative temperature coefficient thermistor.

3. The protection circuit according to claim 1, characterized in that: The first switch tube is a switch transistor, the base of the switch transistor is connected to one end of the thermistor, the collector of the switch transistor is connected to the controlled end of the second switch tube, and the emitter of the switch transistor is grounded.

4. The protection circuit according to claim 1, characterized in that: The second switch tube is an NMOS tube, a gate of the NMOS tube is connected to the first end of the first switch tube, a drain of the NMOS tube is connected to the charging base circuit, and a source of the NMOS tube is grounded.

5. The protection circuit according to claim 1, characterized in that: The protection circuit further includes a first capacitor, one end of the first capacitor is connected to one end of the first resistor, and the other end of the first capacitor is grounded.

6. The protection circuit according to claim 1, characterized in that: The protection circuit further includes a second capacitor, one end of the second capacitor is connected to one end of the thermistor, and the other end of the second capacitor is grounded.

7. The protection circuit according to claim 1, characterized in that: The first resistor is a variable resistor.

8. The protection circuit according to claim 2, characterized in that: The model of the negative temperature coefficient thermistor is SDNT1005X103.

9. A wireless headset charging compartment, characterized in that: The wireless headset charging case includes a protection circuit as described in any one of claims 1 to 8.

10. The wireless headset charging compartment according to claim 9, characterized in that: The wireless headset charging compartment also includes a charging seat circuit, a power supply circuit, a battery, a control circuit and a wireless communication circuit; Among them, the input end of the charging stand circuit is used to connect to the charging adapter, and the output end of the charging stand circuit is respectively connected to the input ends of the protection circuit and the power supply circuit; the output end of the power supply circuit is connected to the battery; and the control circuit is respectively connected to the power supply circuit and the wireless communication circuit.

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