Sensor microphone output stage protection circuit, system, and method

Abstract

The application provides a sensor microphone output stage protection circuit, system and method, which comprises a protection discrimination circuit and a switch circuit; the protection discrimination circuit is connected with a buffer in the sensor microphone and the switch circuit, and the switch circuit is connected with a power tube to be protected in the buffer; the protection discrimination circuit generates a protection signal when the output end of the buffer is directly connected with an external power supply or grounded, and sends the protection signal to the switch circuit; and the switch circuit controls the power tube to be protected to be cut off according to the protection signal, so as to protect the power tube to be protected. In the application, the protection discrimination circuit controls the power tube to be protected to be cut off in time when it is determined that the output end of the buffer is directly connected with the external power supply or grounded, so that the damage of the large current generated by the power supply to the power tube to be protected is effectively avoided.

Description

Technical Field

[0001] The present invention relates to the field of sensor technology, and in particular to a sensor microphone output level protection circuit system and method. Background Art

[0002] With widespread adoption in consumer markets such as modern smartphones, TWS smart earphones, and smart home devices, the demand for sensor microphones has increased significantly. Traditional sensor microphones have a capacitor connected in series at their output to couple AC signals, allowing only AC signals to be transmitted through the capacitor while blocking DC signals. This has the advantage that the sensor microphone's output can be used with any brand of audio codec, meaning the sensor microphone can ignore the effects of the application load. This means that subsequent application circuits can design their own DC bias voltages. Furthermore, the series capacitor is a high-impedance device that does not provide a DC current path and therefore does not generate DC current.

[0003] With the widespread use and improved quality of today's smart products, the PCB circuits of related product systems have become more complex. If the sensor microphone output terminal accidentally contacts the positive or negative power supply signal or a voltage level that differs significantly from the DC voltage level of the sensor microphone output terminal during the device connection process, a large current path will be generated between the chip output stage and the power supply inside the sensor microphone, causing damage to the MOS transistor of the chip output stage.

[0004] The above content is only used to assist in understanding the technical solution of the present invention and does not constitute an admission that the above content is prior art. Summary of the Invention

[0005] The main purpose of the present invention is to provide a sensor microphone output stage protection circuit system and method, aiming to solve the technical problem in the prior art that the power supply of the sensor microphone generates a large current and the power tube is damaged.

[0006] To achieve the above object, the present invention provides a sensor microphone output level protection circuit, the sensor microphone output level protection circuit comprising: a protection determination circuit and a switch circuit;

[0007] The protection discrimination circuit is connected to the buffer in the sensor microphone and the switch circuit, and the switch circuit is connected to the power tube to be protected in the buffer;

[0008] The protection determination circuit is configured to generate a protection signal when the output terminal of the buffer is directly connected to an external power supply or to ground, and send the protection signal to the switch circuit;

[0009] The switch circuit is used to control the power tube to be protected to be cut off according to the protection signal, so as to protect the power tube to be protected.

[0010] Optionally, the protection discrimination circuit includes: a first discrimination circuit and a second discrimination circuit; correspondingly, the switch circuit includes: a first switch circuit and a second switch circuit;

[0011] The first discrimination circuit is connected to the first switch circuit and the output end of the buffer, and the first switch circuit is connected to the control end of the first power transistor in the buffer; the second discrimination circuit is connected to the second switch circuit and the output end of the buffer, and the second switch circuit is connected to the control end of the second power transistor in the buffer;

[0012] The first discrimination circuit is configured to generate a first protection signal when the output terminal of the buffer is directly connected to an external power supply, and send the first protection signal to the first switch circuit;

[0013] The first switch circuit is configured to control the first power tube to be cut off according to the first protection signal, so as to protect the first power tube;

[0014] the second discrimination circuit is configured to generate a second protection signal when the output terminal of the buffer is grounded, and send the second protection signal to the second switch circuit;

[0015] The second switch circuit is used to control the second power tube to be cut off according to the second protection signal, so as to protect the second power tube.

[0016] Optionally, the sensor microphone output stage protection circuit further comprises: a first filtering circuit and a second filtering circuit;

[0017] Wherein, the first filtering circuit is connected to the output end of the buffer and the first discrimination circuit respectively, and the second filtering circuit is connected to the output end of the buffer and the second discrimination circuit respectively;

[0018] The first filtering circuit is configured to filter the output voltage of the buffer to obtain a first DC output voltage, and send the first DC output voltage to the first discrimination circuit;

[0019] The first discrimination circuit is further configured to generate a first protection signal according to the first DC output voltage when the output terminal of the buffer is grounded, and send the first protection signal to the first switch circuit;

[0020] the second filtering circuit is configured to filter the output voltage of the buffer and the power supply voltage of the external power supply to obtain a second DC output voltage when the output end of the buffer is directly connected to the external power supply, and send the second DC output voltage to the second discrimination circuit;

[0021] The second discrimination circuit is further configured to generate a second protection signal according to the second DC output voltage, and send the second protection signal to the second switch circuit.

[0022] Optionally, the first discrimination circuit includes: a first resistor, a second resistor and a first comparator;

[0023] The first end of the first resistor is connected to the power supply, the second end of the first resistor is connected to the positive input end of the first comparator and the first end of the second resistor, the second end of the second resistor is connected to the first filter circuit, the reverse input end of the first comparator is connected to the first reference power supply, and the output end of the first comparator is connected to the first switching circuit.

[0024] Optionally, the first filtering circuit includes: a third resistor and a first capacitor;

[0025] The first end of the third resistor is connected to the second end of the first capacitor and the second end of the second resistor, the second end of the third resistor is connected to the output end of the buffer, and the first end of the first capacitor is grounded.

[0026] Optionally, the second discrimination circuit includes: a fifth resistor, a sixth resistor and a second comparator;

[0027] Among them, the first end of the fifth resistor is connected to the second filtering circuit, the second end of the fifth resistor is respectively connected to the positive input end of the second comparator and the first end of the sixth resistor, the reverse input end of the second comparator is connected to the second reference power supply, the output end of the second comparator is connected to the second switching circuit, and the second end of the sixth resistor is grounded.

[0028] Optionally, the second filtering circuit includes: a fourth resistor and a second capacitor;

[0029] The first end of the fourth resistor is connected to the output end of the buffer, the second end of the fourth resistor is connected to the first end of the second capacitor and the first end of the fifth resistor, and the second end of the second capacitor is grounded.

[0030] Optionally, the first switch circuit includes: a first controllable switch element, and the second switch circuit includes: a second controllable switch element;

[0031] Among them, the control end of the first controllable switch element is connected to the output end of the first comparator, the input end of the first controllable switch element is connected to the power supply, the output end of the first controllable switch element is connected to the control end of the first power tube in the buffer, the control end of the second controllable switch element is connected to the output end of the second comparator, the input end of the second controllable switch element is connected to the control end of the second power tube in the buffer, and the output end of the second controllable switch element is grounded.

[0032] To achieve the above object, the present invention further provides a sensor microphone output level protection system, which includes the above sensor microphone output level protection circuit.

[0033] To achieve the above object, the present invention further proposes a sensor microphone output level protection method, the sensor microphone output level protection method comprising:

[0034] generating a protection signal when the output terminal of the buffer is directly connected to an external power supply or ground;

[0035] The power tube to be protected is controlled to be cut off according to the protection signal to protect the power tube to be protected.

[0036] The present invention provides a sensor microphone output-level protection circuit, system, and method. The sensor microphone output-level protection circuit includes: a protection discrimination circuit and a switch circuit; the protection discrimination circuit is connected to a buffer in the sensor microphone and the switch circuit, and the switch circuit is connected to a power transistor to be protected in the buffer; the protection discrimination circuit generates a protection signal when the output end of the buffer is directly connected to an external power supply or ground, and sends the protection signal to the switch circuit; the switch circuit controls the power transistor to be protected to be cut off according to the protection signal to protect the power transistor to be protected. In the present invention, when the protection discrimination circuit determines that the output end of the buffer is directly connected to an external power supply or ground, the power transistor to be protected is promptly controlled to be cut off, thereby effectively preventing the large current generated by the power supply from damaging the power transistor to be protected. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0038] Figure 1 This is a schematic structural diagram of a first embodiment of a sensor microphone output stage protection circuit proposed in an embodiment of the present invention;

[0039] Figure 2 Circuit diagram for grounding the output terminal of the buffer;

[0040] Figure 3 The circuit diagram of the buffer's output directly connected to an external power supply;

[0041] Figure 4 This is a schematic structural diagram of a second embodiment of a sensor microphone output stage protection circuit proposed in an embodiment of the present invention;

[0042] Figure 5 A circuit diagram of a second embodiment of a sensor microphone output stage protection circuit according to an embodiment of the present invention;

[0043] Figure 6 This is a flow chart of the first embodiment of the sensor microphone output level protection method proposed in an embodiment of the present invention.

[0044] Description of Figure Numbers:

[0045]

[0046] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0047] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0048] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0049] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0050] In addition, the descriptions of "first", "second", etc. in the present invention are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of such features. In addition, the technical solutions between the various embodiments can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0051] Reference Figure 1 , Figure 1 This is a schematic diagram of the structure of the first embodiment of the sensor microphone output stage protection circuit proposed in the embodiment of the present invention. Figure 1 , a first embodiment of the sensor microphone output stage protection circuit of the present invention is proposed.

[0052] In this embodiment, the sensor microphone output stage protection circuit includes: a protection determination circuit 10 and a switch circuit 20;

[0053] The protection determination circuit 10 is connected to the buffer in the sensor microphone and the switch circuit 20 , and the switch circuit 20 is connected to the power tube to be protected in the buffer.

[0054] It should be understood that referring to Figure 2 and Figure 3 The buffer inside the sensor microphone includes two power transistors. When outputting a voltage, the buffer outputs a certain voltage by controlling the on / off switches of the two power transistors. When the buffer output stage is directly grounded, the internal power supply VDD of the buffer is directly connected to ground through the first power transistor T1. This causes a large current to flow through the first power transistor T1, potentially damaging it. When the buffer output stage is directly connected to an external power supply, the buffer output voltage may be low. The external power supply then flows directly to ground through the second power transistor T2, causing a large current to flow through the second power transistor T2, potentially damaging it.

[0055] It should be noted that the protection determination circuit 10 is used to determine whether the buffer within the sensor microphone is directly connected to an external power supply or ground. The switch circuit 20 is used to control the conduction or disconnection of the circuit connecting the protected power transistor and the power supply. If the power supply is directly connected to ground through the protected power transistor, the switch circuit 20 disconnects the power supply from the protected power transistor. The switch circuit 20 is composed of switching components and other related elements, and its specific structure is not limited here.

[0056] In a specific implementation, the protection judgment circuit 10 can judge whether the output stage of the buffer is directly connected to an external power supply or ground based on the voltage value at the output end of the buffer, and generate a protection signal when the output end of the buffer is directly connected to an external power supply or ground, and send the protection signal to the switching circuit 20; the switching circuit 20 can control the power tube to be protected to be cut off according to the protection signal to protect the power tube to be protected.

[0057] The voltage at the buffer output includes the voltage outputted internally by the buffer and the voltage supplied by the external power supply. When the buffer output is directly grounded, the voltage detected by the protection detection circuit 10 is zero. When the buffer output is directly connected to an external power supply, the voltage detected by the protection detection circuit 10 is significantly greater than the rated voltage of the power transistor to be protected. The protection signal is used to control the disconnection of the switching element within the switching circuit. When the switching element disconnects, the circuit between the protected power transistor and the power supply is disconnected.

[0058] This embodiment provides a sensor microphone output-stage protection circuit, comprising: a protection determination circuit and a switch circuit; the protection determination circuit is connected to a buffer within the sensor microphone and the switch circuit, and the switch circuit is connected to a power transistor to be protected within the buffer; the protection determination circuit generates a protection signal when the output of the buffer is directly connected to an external power supply or ground, and transmits the protection signal to the switch circuit; the switch circuit controls the power transistor to be protected to be cut off based on the protection signal to protect the power transistor to be protected. In this embodiment, when the protection determination circuit determines that the output of the buffer is directly connected to an external power supply or ground, the power transistor to be protected is promptly cut off, thereby effectively preventing damage to the power transistor to be protected caused by high current generated by the power supply.

[0059] Reference Figure 4 , Figure 4 This is a schematic structural diagram of a second embodiment of a sensor microphone output stage protection circuit proposed in an embodiment of the present invention. Based on the first embodiment of the sensor microphone output stage protection circuit, a second embodiment of the sensor microphone output stage protection circuit is proposed.

[0060] In this embodiment, the protection determination circuit 10 includes: a first determination circuit 101 and a second determination circuit 102; correspondingly, the switch circuit includes: a first switch circuit 201 and a second switch circuit 202;

[0061] Among them, the first discrimination circuit 101 is connected to the first switch circuit 201 and the output end of the buffer, and the first switch circuit 101 is connected to the control end of the first power tube T1 in the buffer; the second discrimination circuit 201 is connected to the second switch circuit 202 and the output end of the buffer, and the second switch circuit 202 is connected to the control end of the second power tube T2 in the buffer.

[0062] It should be understood that the buffer usually includes two power tubes to be protected, and the damage to the first power tube T1 and the second power tube T2 occurs under different external connection conditions. In this case, the protection judgment circuit 10 can be divided into two judgment circuits to judge whether the output end of the buffer is directly connected to the external power supply and the ground respectively. For example, the first judgment circuit 101 is used to judge whether the output end of the buffer is directly connected to the external power supply DC, while the second judgment circuit 102 can judge whether the output end of the buffer is directly connected to the ground GND. Among them, in this embodiment, the power tubes to be protected include the first power tube T1 and the second power tube T2. In this case, the switch circuit 20 can be set to a first switch circuit 201 and a second switch circuit 202. The first switch circuit 201 can control the connection between the power supply VDD inside the buffer and the first power tube T1, and the second switch circuit 202 can control the connection between the external power supply DC and the second power tube T2.

[0063] In a specific implementation, the first judgment circuit 101 can generate a first protection signal when the output end of the buffer is directly connected to an external power supply, and send the first protection signal to the first switching circuit 201; the first switching circuit 201 can control the first power tube T1 to be cut off according to the first protection signal to protect the first power tube T1; the second judgment circuit 102 can generate a second protection signal when the output end of the buffer is grounded, and send the second protection signal to the second switching circuit 202; the second switching circuit 202 can control the second power tube T2 to be cut off according to the second protection signal to protect the second power tube T2.

[0064] In this embodiment, the sensor microphone output stage protection circuit further includes: a first filter circuit 301 and a second filter circuit 302;

[0065] The first filtering circuit 301 is connected to the output end of the buffer and the first discrimination circuit 101 respectively, and the second filtering circuit 302 is connected to the output end of the buffer and the second discrimination circuit 102 respectively.

[0066] It should be noted that the voltage or current output from the buffer output includes a DC component and an AC component. Since the specific value of the AC component's voltage or current is constantly changing, this AC component does not damage the protected power transistor. Therefore, only the DC component's voltage or current needs to be considered for damage. Furthermore, the changing voltage or current can affect the voltage collected by the protection determination circuit 10 at the buffer output, so this AC component must be filtered out. In this embodiment, the AC component of the buffer output can be filtered out using a low-pass filter to prevent it from affecting the voltage collected at the buffer output.

[0067] It should be understood that the first filter circuit 301 is a circuit for filtering out the AC component in the voltage output by the buffer when the output terminal of the buffer is grounded GND. The second filter circuit 302 is a circuit for filtering out the AC component in the voltage output by the buffer when the output terminal of the buffer is directly connected to an external power supply DC.

[0068] In a specific implementation, when the output terminal of the buffer is directly grounded to GND, the first filter circuit 301 can filter the output voltage of the buffer to obtain a first DC output voltage and send the first DC output voltage to the first determination circuit 101. When the output terminal of the buffer is grounded, the first determination circuit 101 can generate a first protection signal based on the first DC output voltage and send the first protection signal to the first switch circuit 201 to disconnect the internal power supply VCC from the first power transistor T1, thereby protecting the first power transistor T1. When the output terminal of the buffer is directly connected to an external power supply DC, the second filter circuit 302 can filter the output voltage of the buffer and the power supply voltage of the external power supply DC to obtain a second DC output voltage. Of course, if the external power supply DC does not include an AC component, filtering of the external power supply DC is not required. The second DC output voltage is sent to the second determination circuit 102. The second determination circuit 102 can generate a second protection signal based on the second DC output voltage and send the second protection signal to the second switch circuit 202 to disconnect the circuit between the external power supply DC and the second power transistor T2, thereby protecting the second power transistor T2.

[0069] In this embodiment, the first discrimination circuit 101 may be divided into a first step-down circuit and a first comparison circuit; and the second discrimination circuit may be divided into a second step-down circuit and a second comparison circuit.

[0070] The first step-down circuit is connected to the power supply VCC, the output end of the buffer and the first comparison circuit respectively, and the first comparison circuit is connected to the first switch circuit 201; the second step-down circuit is connected to the output end of the buffer and the second comparison circuit, and the second comparison circuit is connected to the second switch circuit 202.

[0071] It should be understood that the first step-down circuit can step down the power supply voltage of the power supply to obtain a first step-down voltage, and output the first step-down voltage to the first comparison circuit; the first comparison circuit can compare the first step-down voltage with a first preset reference voltage, and when the first step-down voltage is less than the first preset reference voltage, output a first protection signal to the first switch circuit 201 to protect the first power tube T1; the second step-down circuit can step down the output voltage of the buffer and the power supply voltage of the external power supply to obtain a second reduced-pressure voltage, and output the second step-down voltage to the second comparison circuit; the second comparison circuit can compare the second step-down voltage with a second preset reference voltage, and when the second step-down voltage is greater than the second preset reference voltage, output a second protection signal to the second switch circuit 202 to protect the second power tube T2.

[0072] Reference Figure 5 In this embodiment, the first discrimination circuit 101 includes: a first resistor R1, a second resistor R2 and a first comparator Q1;

[0073] The first end of the first resistor R1 is connected to the power supply VCC, the second end of the first resistor R1 is connected to the positive input end of the first comparator Q1 and the first end of the second resistor R2, the second end of the second resistor R2 is connected to the first filter circuit 301, the negative input end of the first comparator Q1 is connected to the first reference power supply VREFP, and the output end of the first comparator Q1 is connected to the first switch circuit 201.

[0074] In this embodiment, the first filtering circuit 301 includes: a third resistor R3 and a first capacitor C1;

[0075] The first end of the third resistor R3 is connected to the second end of the first capacitor C1 and the second end of the second resistor R2, the second end of the third resistor R3 is connected to the output end of the buffer, and the first end of the first capacitor C1 is grounded.

[0076] It should be noted that the first reference power supply VREFP is used as a power supply for comparing the voltage input to the negative input terminal of the first comparator Q1 with the voltage input to the positive input terminal. When the output terminal of the buffer is directly connected to GND, the power supply VCC is connected to ground through the first to third resistors, and a first voltage signal is input to the positive input terminal of the first comparator Q1 at the second terminal of the first resistor R1. When the positive output terminal of the buffer is connected to a load, the power supply VCC is connected to ground through the first to third resistors, and a second voltage signal is input to the positive input terminal of the first comparator Q1 at the second terminal of the first resistor R1. Here, the voltage value of the first reference power supply VREFP should be greater than the voltage value of the first voltage signal and less than the voltage value of the second voltage signal.

[0077] It should be understood that, in this embodiment, the first power tube T1 is turned on when the control terminal is at a low level, and the first switch circuit 201 is also turned on when the control terminal is at a low level.

[0078] In a specific implementation, the first filter circuit 301 composed of the first capacitor C1 and the third resistor R3 can filter out the AC component at the buffer output. When the buffer output is directly grounded, the power supply voltage VCC is input into the positive input terminal of the first comparator Q1 via the voltage drop between the first and third resistors. Since the voltage value of the first voltage signal is less than the voltage value of the first reference power supply VREFP, the first comparator Q1 outputs a low-level signal. This low-level signal can turn on the first switch circuit 101, thereby inputting the power supply voltage VCC into the control terminal of the first power transistor T1, controlling the first power transistor T1 to be turned off, thereby protecting the first power transistor T1. Of course, when the output end of the buffer is connected to a normal load, the voltage value of the second voltage signal of the power supply VCC input to the positive input end of the first comparator Q1 after being stepped down by the first to third resistors is greater than the voltage value of the first reference power supply VREFP. The first comparator Q1 outputs a high-level signal, the first switch circuit 201 is turned off, and the control end of the first power transistor T1 remains in a low-level state, that is, the first power transistor T1 is turned on. The power supply voltage VCC can be normally output to the load through the first power transistor T1.

[0079] In this embodiment, the second discrimination circuit 102 includes: a fifth resistor R5, a sixth resistor R6 and a second comparator Q2;

[0080] Among them, the first end of the fifth resistor R5 is connected to the second filtering circuit 302, the second end of the fifth resistor R5 is respectively connected to the positive input end of the second comparator Q2 and the first end of the sixth resistor R6, the reverse input end of the second comparator Q2 is connected to the second reference power supply VREFN, the output end of the second comparator Q2 is connected to the second switching circuit 201, and the second end of the sixth resistor R6 is grounded GND.

[0081] In this embodiment, the second filtering circuit 302 includes: a fourth resistor R4 and a second capacitor C2;

[0082] The first end of the fourth resistor R4 is connected to the output end of the buffer, the second end of the fourth resistor R4 is connected to the first end of the second capacitor C2 and the first end of the fifth resistor R5, and the second end of the second capacitor C2 is grounded GND.

[0083] It should be noted that the second reference power supply VREFN is used as a power supply for comparing the voltage input to the negative input terminal of the second comparator Q2 with the voltage input to the positive input terminal. When the output terminal of the buffer is directly connected to the external power supply DC, the external power supply DC and the voltage output by the buffer are connected to ground through the fourth to sixth resistors, and the corresponding first voltage signal is input to the positive input terminal of the second comparator Q2 at the first end of the fourth resistor R4. When the positive output terminal of the buffer is connected to a load, the power supply VCC is connected to ground through the fourth to sixth resistors, and the corresponding second voltage signal is input to the positive input terminal of the second comparator Q2 at the first end of the fourth resistor R4. Here, the voltage value of the second reference power supply VREFP should be less than the voltage value of the corresponding first voltage signal and greater than the voltage value of the corresponding second voltage signal.

[0084] It should be understood that, in this embodiment, the second power transistor T1 is turned on when the control terminal is at a high level, and the control terminal of the second switch circuit 202 is also turned on when the control terminal is at a high level.

[0085] In a specific implementation, the second filter circuit 302 composed of the second capacitor C2 and the fourth resistor R4 can filter out the AC component at the buffer output. When the buffer output is directly connected to the external power supply DC, the power supply voltage VCC and the external power supply DC are connected via the voltage drop across the fourth to sixth resistors to input a corresponding first voltage signal to the positive input terminal of the second comparator Q2. Because the voltage value of the corresponding first voltage signal is greater than the voltage value of the second reference power supply VREFN, the second comparator Q2 outputs a high-level signal. This high-level signal can turn on the second switch circuit 102, thereby grounding the control terminal of the second power transistor T2 to GND, turning off the second power transistor T2 and protecting the second power transistor T2. Of course, when a normal load is connected to the output end of the buffer, the voltage value of the second voltage signal corresponding to the power supply VCC input to the positive input end of the second comparator Q2 after being stepped down by the fourth to sixth resistors is less than the voltage value of the second reference power supply VREFN. The second comparator Q2 outputs a low-level signal, the second switch circuit 202 is turned off, and the control end of the second power transistor T2 remains in a high-level state, that is, the second power transistor T2 is turned on. The voltage on the load can be normally grounded through the second power transistor T2.

[0086] In this embodiment, the first switch circuit 201 includes: a first controllable switch element M1, and the second switch circuit 202 includes: a second controllable switch element M2;

[0087] The control end of the first controllable switch element M1 is connected to the output end of the first comparator Q1, the input end of the first controllable switch element M1 is connected to the power supply VCC, the output end of the first controllable switch element M1 is connected to the control end of the first power tube T1 in the buffer, the control end of the second controllable switch element M2 is connected to the output end of the second comparator Q2, the input end of the second controllable switch element M2 is connected to the control end of the second power tube T2 in the buffer, and the output end of the second controllable switch element M2 is connected to the ground GND.

[0088] It should be noted that the first controllable switch element M1 is an element that conducts when the control terminal is at a low level. The first controllable switch element M1 can be a power transistor such as a PNP transistor or a PMOS transistor. The second controllable switch element M2 is an element that conducts when the control terminal is at a high level. The second controllable switch element M2 can be a power transistor such as an NPN transistor or an NMOS transistor.

[0089] In a specific implementation, when the first comparator Q1 outputs a low-level signal, the first controllable switch element M1 is turned on. At this time, the power supply VCC can directly input voltage to the control terminal of the first power transistor T1 through the first controllable switch element M1, controlling the first power transistor T1 to be turned off and protecting the first power transistor T1. When the first comparator Q1 outputs a high-level signal, the first controllable switch element M1 is turned off. At this time, the control terminal of the first power transistor T1 remains in a low-level state, that is, the first power transistor T1 is turned on and can normally transmit voltage signals. When the second comparator Q2 outputs a high-level signal, the second controllable switch element M2 is turned on, thereby grounding the control terminal of the second power transistor T2, that is, turning off the second power transistor T2 and protecting the second power transistor T2. When the second comparator Q2 outputs a low-level signal, the second controllable switch element M2 is turned off, and the control terminal of the second power transistor T2 remains in a high-level state, that is, the second power transistor T2 is turned on and can normally transmit voltage signals.

[0090] This embodiment provides a sensor microphone output-stage protection circuit, comprising: a protection discrimination circuit and a switch circuit; the protection discrimination circuit is connected to a buffer within the sensor microphone and the switch circuit, and the switch circuit is connected to a power transistor to be protected within the buffer; the protection discrimination circuit generates a protection signal when the output terminal of the buffer is directly connected to an external power supply or ground, and sends the protection signal to the switch circuit; the switch circuit controls the power transistor to be protected to be cut off according to the protection signal to protect the power transistor to be protected. In this embodiment, when the protection discrimination circuit determines that the output terminal of the buffer is directly connected to an external power supply or ground, different discrimination circuits and different switch circuits are used to promptly control the first power transistor or the second power transistor to be cut off, thereby effectively preventing the large current generated by the power supply from damaging the power transistor to be protected.

[0091] To achieve the above objectives, the present invention further provides a sensor microphone output-level protection system, comprising the sensor microphone output-level protection circuit described above. The specific structure of the sensor microphone output-level protection circuit is similar to that of the aforementioned embodiments. Since the present sensor microphone output-level protection system utilizes all the technical solutions of all the aforementioned embodiments, it possesses at least all the beneficial effects of the technical solutions of the aforementioned embodiments, and therefore will not be further elaborated upon here.

[0092] To achieve the above object, the present invention also proposes a sensor microphone output level protection method, referring to Figure 6 , Figure 6 This is a flow chart of the first embodiment of the sensor microphone output level protection method proposed in an embodiment of the present invention.

[0093] In this embodiment, the sensor microphone output level protection method includes:

[0094] Step S10: generating a protection signal when the output end of the buffer is directly connected to an external power supply or grounded;

[0095] Step S20: controlling the power tube to be protected to be turned off according to the protection signal to protect the power tube to be protected.

[0096] It should be understood that the buffer within the sensor microphone includes two power transistors. When the buffer outputs a voltage, it outputs a certain voltage by controlling the on / off switches of the two power transistors. When the buffer output stage is directly grounded, the power supply within the buffer is directly connected to the ground through the first power transistor. This causes a large current to flow through the first power transistor, potentially damaging it. When the buffer output stage is directly connected to an external power supply, the buffer output voltage may be low. In this case, the external power supply is directly connected to the ground through the second power transistor, causing a large current to flow through the second power transistor, potentially damaging it.

[0097] It should be noted that the protection determination circuit determines whether the buffer within the sensor microphone is directly connected to an external power supply or ground. The switching circuit controls the conduction or disconnection of the circuit connecting the protected power transistor to the power supply. If the power supply is directly connected to ground through the protected power transistor, the switching circuit disconnects the power supply from the protected transistor. The switching circuit consists of switching components and other related elements, and its specific structure is not specified here.

[0098] In a specific implementation, the protection judgment circuit can judge whether the output stage of the buffer is directly connected to an external power supply or ground based on the voltage value at the output end of the buffer, generate a protection signal when the output end of the buffer is directly connected to an external power supply or ground, and send the protection signal to the switching circuit; the switching circuit can control the power tube to be protected to be cut off according to the protection signal to protect the power tube to be protected.

[0099] The voltage at the buffer output includes the voltage outputted internally by the buffer and the voltage supplied by the external power supply. When the buffer output is directly grounded, the voltage detected by the protection detection circuit is zero. When the buffer output is directly connected to an external power supply, the voltage detected by the protection detection circuit is significantly greater than the rated voltage of the power transistor to be protected. The protection signal is used to control the disconnection of the switching element within the switching circuit. When the switching element disconnects, the circuit between the power transistor to be protected and the power supply is disconnected.

[0100] This embodiment provides a sensor microphone output-level protection method, comprising: generating a protection signal when the output terminal of the buffer is directly connected to an external power supply or ground, and transmitting the protection signal to the switching circuit; and controlling the power transistor to be protected to be cut off based on the protection signal to protect the power transistor to be protected. In this embodiment, when the protection determination circuit determines that the output terminal of the buffer is directly connected to an external power supply or ground, the power transistor to be protected is promptly cut off, thereby effectively preventing damage to the power transistor to be protected due to the high current generated by the power supply.

[0101] In addition, the sensor microphone output level protection method of the present invention also includes other steps. Since the sensor microphone output level protection method is based on the above-mentioned sensor microphone output level protection system, the relevant control logic involved in the sensor microphone output level protection system is within the protection scope of the sensor microphone output level protection method of the present invention.

[0102] The above are only preferred embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A sensor microphone output stage protection circuit, characterized in that: The sensor microphone output level protection circuit includes: a protection discrimination circuit and a switch circuit; The protection discrimination circuit is connected to a buffer in the sensor microphone and the switch circuit, the switch circuit is connected to the power tube to be protected in the buffer, the buffer includes two power tubes, and the buffer outputs a voltage by controlling the on / off switches of the two power tubes when outputting a voltage; The protection determination circuit is configured to generate a protection signal when the output terminal of the buffer is directly connected to an external power supply or to ground, and send the protection signal to the switch circuit; The switch circuit is used to control the power tube to be protected to be cut off according to the protection signal, so as to protect the power tube to be protected; The protection discrimination circuit includes: a first discrimination circuit, a second discrimination circuit, a first filtering circuit and a second filtering circuit; correspondingly, the switch circuit includes: a first switch circuit and a second switch circuit; The first filter circuit is connected to the output end of the buffer and the first discrimination circuit respectively, the second filter circuit is connected to the output end of the buffer and the second discrimination circuit respectively, the first discrimination circuit is connected to the first switch circuit, the first switch circuit is connected to the control end of the first power transistor in the buffer; the second discrimination circuit is connected to the second switch circuit, the second switch circuit is connected to the control end of the second power transistor in the buffer; The first filtering circuit is configured to filter the output voltage of the buffer to obtain a first DC output voltage, and send the first DC output voltage to the first discrimination circuit; the first discrimination circuit is configured to generate a first protection signal according to the first DC output voltage when the output terminal of the buffer is grounded, and send the first protection signal to the first switch circuit; The first switch circuit is configured to control the first power tube to be cut off according to the first protection signal, so as to protect the first power tube; the second filtering circuit is configured to filter the output voltage of the buffer and the power supply voltage of the external power supply to obtain a second DC output voltage when the output end of the buffer is directly connected to the external power supply, and send the second DC output voltage to the second discrimination circuit; The second discrimination circuit is further configured to generate a second protection signal according to the second DC output voltage, and send the second protection signal to the second switch circuit; The second switch circuit is used to control the second power tube to be cut off according to the second protection signal, so as to protect the second power tube.

2. The sensor microphone output stage protection circuit according to claim 1, wherein: The first discrimination circuit includes: a first resistor, a second resistor and a first comparator; The first end of the first resistor is connected to the power supply, the second end of the first resistor is connected to the positive input end of the first comparator and the first end of the second resistor, the second end of the second resistor is connected to the first filter circuit, the reverse input end of the first comparator is connected to the first reference power supply, and the output end of the first comparator is connected to the first switching circuit.

3. The sensor microphone output stage protection circuit according to claim 2, wherein: The first filtering circuit includes: a third resistor and a first capacitor; The first end of the third resistor is connected to the second end of the first capacitor and the second end of the second resistor, the second end of the third resistor is connected to the output end of the buffer, and the first end of the first capacitor is grounded.

4. The sensor microphone output stage protection circuit according to claim 3, wherein: The second discrimination circuit includes: a fifth resistor, a sixth resistor and a second comparator; Among them, the first end of the fifth resistor is connected to the second filtering circuit, the second end of the fifth resistor is respectively connected to the positive input end of the second comparator and the first end of the sixth resistor, the reverse input end of the second comparator is connected to the second reference power supply, the output end of the second comparator is connected to the second switching circuit, and the second end of the sixth resistor is grounded.

5. The sensor microphone output stage protection circuit according to claim 4, wherein: The second filtering circuit includes: a fourth resistor and a second capacitor; The first end of the fourth resistor is connected to the output end of the buffer, the second end of the fourth resistor is connected to the first end of the second capacitor and the first end of the fifth resistor, and the second end of the second capacitor is grounded.

6. The sensor microphone output stage protection circuit according to claim 5, wherein: The first switch circuit includes: a first controllable switch element, and the second switch circuit includes: a second controllable switch element; Among them, the control end of the first controllable switch element is connected to the output end of the first comparator, the input end of the first controllable switch element is connected to the power supply, the output end of the first controllable switch element is connected to the control end of the first power tube in the buffer, the control end of the second controllable switch element is connected to the output end of the second comparator, the input end of the second controllable switch element is connected to the control end of the second power tube in the buffer, and the output end of the second controllable switch element is grounded.

7. A sensor microphone output level protection system, characterized in that: The sensor microphone output level protection system comprises the sensor microphone output level protection circuit according to any one of claims 1 to 6.

8. A sensor microphone output level protection method based on the sensor microphone output level protection system according to claim 7, characterized in that: The sensor microphone output level protection method includes: generating a protection signal when the output terminal of the buffer is directly connected to an external power supply or ground; The power tube to be protected is controlled to be cut off according to the protection signal to protect the power tube to be protected.

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