An audio signal overcurrent protection circuit

Abstract

The utility model relates to overcurrent protection technical field discloses an audio signal overcurrent protection circuit with fast response, low noise interference and strong recovery ability, including the main control module (MCU) for output at least one way power amplifier signal, at least one switch module (110 140) and current -limiting module (150), wherein, when input power amplifier signal is greater than the preset value of switch module (110 140), switch module (110 140) is controlled to conduct, and then triggers current -limiting module (150) to conduct, and the main control module (MCU) stops output power amplifier signal according to the level signal state of current -limiting module (150) output.

Description

Technical Field

[0001] This utility model relates to the field of overcurrent protection technology, and more specifically, to an audio signal overcurrent protection circuit. Background Technology

[0002] In recent years, audio technology has been iterating and upgrading at an astonishing pace. From consumer-grade Bluetooth headphones and smart speakers to professional-grade stage amplifiers and recording studio monitoring systems, audio products have deeply penetrated into various scenarios of life and industry. In various audio devices, the power amplifier module is the core unit for power amplification. When driving loads such as speakers, various sudden situations may cause the output current to surge sharply. For example, a momentary short circuit in the speaker voice coil or a sudden impedance change caused by poor cable contact may cause the power amplifier tube to withstand a current surge far exceeding the rated value. However, existing protection solutions always have irreconcilable technical contradictions. Although traditional fuses are inexpensive, their response speed is only in the millisecond range, which is much slower than the damage threshold of the power amplifier tube (usually less than 10 microseconds). Often, "the protection has not been triggered, but the device has already burned out," which cannot meet the continuous operation requirements of the equipment. Although the response speed of electronic protection circuits based on operational amplifier comparators is improved, the complexity of the circuit topology can easily introduce additional noise, which, after being amplified by the power amplifier, directly contaminates the audio signal, resulting in sound quality distortion, a decrease in signal-to-noise ratio, and affecting the purity of the audio signal and the normal operation of the equipment. Summary of the Invention

[0003] The technical problem to be solved by this utility model is that the above-mentioned traditional overcurrent protection schemes in the prior art may introduce noise due to circuit complexity, or cause false triggering due to rough protection threshold settings, which affects the purity of audio signals and normal operation of equipment. This utility model provides an audio signal overcurrent protection circuit with fast response, low noise interference and strong recovery capability.

[0004] The technical solution adopted by this utility model to solve its technical problem is: to construct an audio signal overcurrent protection circuit, which has the following features: The main control module is used to output at least one power amplifier signal; At least one switching module, whose first signal input terminal is connected to the output terminal of the main control module, is used to receive the power amplifier signal. The second signal input terminal of the switch module is connected to the power supply terminal; The current limiting module has its first signal input terminal connected to the second signal input terminal of the switching module. The second signal input terminal of the current limiting module is connected to the power supply terminal. The output terminal of the current limiting module is connected to one input terminal of the main control module to obtain a level signal; When the input power amplifier signal is greater than the preset value of the switching module, the switching module is controlled to turn on, thereby triggering the current limiting module to turn on. The main control module stops outputting the power amplifier signal according to the level signal status output by the current limiting module.

[0005] In some embodiments, the switching module includes a first branch, a second branch, a third branch, and a fourth branch connected in parallel. The first signal input terminals of the first branch, the second branch, the third branch, and the fourth branch are connected to the output terminal of the main control module. The second signal input terminals of the first branch, the second branch, the third branch, and the fourth branch are connected to the power supply terminal; The second signal input terminals of the first branch, the second branch, the third branch, and the fourth branch are also connected to the first signal input terminal of the current limiting module.

[0006] In some embodiments, the first branch includes a first transistor, a first resistor, a second resistor, and a third resistor. The base of the first transistor is connected to one end of the first resistor and one end of the third resistor. The collector of the first transistor is connected to the first signal input terminal of the current limiting module. The collector of the first transistor is connected to the power supply terminal through a fourth resistor. The other end of the first resistor and one end of the second resistor are respectively connected to the output terminal of the main control module. The other end of the second resistor and the other end of the third resistor are respectively connected to the emitter of the first transistor.

[0007] In some implementations, the first transistor is selected as an NPN transistor.

[0008] In some embodiments, the current limiting module includes at least a second transistor and a fifth resistor. The base of the second transistor is connected to the collector of the first transistor. The emitter of the second transistor is connected to the power supply terminal. The collector of the second transistor is connected to one end of the fifth resistor. The other end of the fifth resistor is coupled to an input terminal of the main control module.

[0009] In some embodiments, the current limiting module further includes a Zener diode and a sixth resistor connected in parallel. The cathode of the Zener diode and one end of the sixth resistor are respectively connected to an input terminal of the main control module. The anode of the Zener diode and the other end of the sixth resistor are respectively connected to the common terminal.

[0010] In some implementations, the second transistor is selected as a PNP transistor.

[0011] The audio signal overcurrent protection circuit described in this utility model includes a main control module for outputting at least one power amplifier signal, at least one switching module, and a current limiting module. When the input power amplifier signal exceeds a preset value of the switching module, the switching module is turned on, thereby triggering the current limiting module to turn on. The main control module then stops outputting the power amplifier signal based on the level signal output by the current limiting module. Compared with existing technologies, when an overcurrent occurs in the downstream load, the switching module can quickly change its conduction state, promptly limiting or cutting off the output current. This effectively prevents permanent damage to critical audio equipment components such as the power amplifier due to prolonged overcurrent, improving the safety and reliability of the equipment. Attached Figure Description

[0012] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 This is a circuit diagram of an embodiment of the audio signal overcurrent protection circuit provided by this utility model. Detailed Implementation

[0013] To provide a clearer understanding of the technical features, objectives, and effects of this utility model, the specific embodiments of this utility model will now be described in detail with reference to the accompanying drawings.

[0014] like Figure 1 As shown, in the first embodiment of the audio signal overcurrent protection circuit of this utility model, the audio signal overcurrent protection circuit 10 includes at least a main control module MCU, at least one switching module (110-140), and a current limiting module 150. The main control module (MCU) has the functions of logic operation, signal reception / processing, and outputting power amplifier signals or level signals. The switch module (110-140) has the function of controlling the on / off state of the control signal; The current limiting module 150 has the functions of switching, current limiting, and signal output; Specifically, the main control module MCU is configured within the protection circuit to output at least one power amplifier signal; Furthermore, the first signal input terminal of the switch module (110-140) is connected to the output terminal of the main control module MCU to receive the power amplifier signal input by the main control module MCU. The input power amplifier signal is used to trigger the on / off state. The second signal input terminal of the switching module (110-140) is connected to the power supply terminal (corresponding to +PWVS) to provide a positive bias voltage to the switching module (110-140); Furthermore, the first signal input terminal of the current limiting module 150 is connected to the second signal input terminal of the switching module (110-140). The second signal input terminal of the current limiting module 150 is connected to the power supply terminal (corresponding to +PWVS). The output terminal of the current limiting module 150 is connected to one input terminal (corresponding to the PROR terminal) of the main control module MCU to obtain the level signal output by the current limiting module 150 when it is controlled to be turned on; Specifically, when any power amplifier signal input to the main control module MCU is greater than the preset value (e.g., 0.7V) of the switch module (110-140), the switch module (110-140) is controlled to be turned on, thereby triggering the current limiting module 150 to be turned on. The main control module MCU stops outputting the power amplifier signal according to the level signal status output by the current limiting module 150.

[0015] That is, when the input power amplifier signal is less than 0.7V, any of the switching modules (110-140) is in the off state, and it can output an audio signal accordingly; When the input power amplifier signal current increases sharply (greater than 0.7V), any of the switching modules (110-140) is turned on, which in turn triggers the current limiting module 150 to turn on. At this time, the main control module MCU can stop outputting the power amplifier signal according to the level signal (such as high level) output when the current limiting module 150 is turned on, so as to control the corresponding switching module (110-140) to switch from on to off, so as to ensure the safety of equipment operation.

[0016] When an overcurrent occurs in the downstream load, the switching module (110-140) can quickly change the conduction state, which can limit or cut off the output current in time. This can effectively prevent permanent damage to key audio equipment components such as power amplifiers due to prolonged overcurrent, thus improving the safety and reliability of the equipment.

[0017] In some embodiments, the switch module (110-140) includes a first branch 110, a second branch 120, a third branch 130, and a fourth branch 140 connected in parallel, wherein the first branch 110 and the second branch 120 control the audio signal output state of the left channel. The third branch 130 and the fourth branch 140 control the audio signal output status of the right channel. The first signal input terminals of the first branch 110, the second branch 120, the third branch 130, and the fourth branch 140 are connected to the output terminals of the main control module MCU. The second signal input terminals of the first branch 110, the second branch 120, the third branch 130 and the fourth branch 140 are connected to the power supply terminal (corresponding to +PWVS); The second signal input terminals of the first branch 110, the second branch 120, the third branch 130, and the fourth branch 140 are also connected to the first signal input terminal of the current limiting module 150.

[0018] In some implementations, to ensure the safe operation of the audio device, a first transistor Q1, a first resistor R20, a second resistor R18, and a third resistor R28 can be provided in the first branch 110. Among them, the first transistor Q1 acts as a switch and is selected as an NPN transistor. The resistance value of the first resistor R20 is selected as 100R. The resistance value of the second resistor R18 is chosen to be 0.1R. The third resistor R28 is selected with a resistance of 1KΩ. It, together with the resistors mentioned above, forms a voltage divider circuit to divide the voltage input to the base of the first transistor Q1. Specifically, one end of the first resistor R20 and the second resistor R18 are respectively connected to the output terminal of the main control module MCU, which is used to receive the power amplifier signal input from the main control module MCU and perform voltage division processing on the input power amplifier signal. The base of the first transistor Q1 is connected to the other end of the first resistor R20. One end of the third resistor R28 is also connected to the base of the first transistor Q1. The collector of the first transistor Q1 is connected to the first signal input terminal of the current limiting module 150. The collector of the first transistor Q1 is connected to the power supply terminal (corresponding to +PWVS) through the fourth resistor R29. The other end of the second resistor R18 and the other end of the third resistor R28 are respectively connected to the emitter of the first transistor Q1.

[0019] In some implementations, to ensure the safe operation of the audio device, a second transistor Q2 and a fifth resistor R26 can be included in the current limiting module 150. The second transistor, Q2, is a PNP transistor, which functions as a switch. The fifth resistor R26 is selected with a resistance value of 10K, which has the function of current limiting; Specifically, the base of the second transistor Q2 is connected to the collector of the first transistor Q1. The emitter of transistor Q2 is connected to the power supply terminal (corresponding to +PWVS) to provide it with a forward bias voltage. In this configuration, the collector of the second transistor Q2 is connected to one end of the fifth resistor R26. The other end of the fifth resistor R26 is coupled to an input terminal of the main control module MCU (corresponding to the PROR terminal).

[0020] When the first transistor Q1 is turned on, the base voltage of the second transistor Q2 is pulled down and it is turned on, which pulls down the voltage at the power supply terminal (corresponding to +PWVS), causing the collector of the first transistor Q1 to lose its positive bias voltage, and the control changes from on to off.

[0021] In some embodiments, the current limiting module 150 further includes a Zener diode Z2 and a sixth resistor R27 connected in parallel. Specifically, the cathode of Zener diode Z2 and one end of the sixth resistor R27 are respectively connected to an input terminal (corresponding to the PROR terminal) of the main control module MCU. The anode of Zener diode Z2 and the other end of the sixth resistor R27 are connected to the common terminal, respectively.

[0022] Specifically, the voltage / current at the output of the power amplifier (single) is divided / sampled by the first resistor R20, the second resistor R18 and the third resistor R28, and then input to the base of the first transistor Q1. The collector of the first transistor Q1 is connected to the power supply terminal (corresponding to +PWVS) through the fourth resistor R29. The emitter of the first transistor Q1 and the third resistor R28 are grounded. At the same time, the collector of the first transistor Q1 is connected to the base of the second transistor Q2. The voltage at the power supply terminal (corresponding to +PWVS) goes through the emitter-collector-fifth resistor R26-Zenyl diode Z2-sixth resistor R27 to PGND. Normal working status: The voltage VR18 across the second resistor R18 is I × 0.1R (much less than 0.7V). The base potential of the first transistor Q1 is lower than its emitter potential, so Q1 is cut off. The second transistor Q2 is also cut off, and the protection circuit is "silent," not affecting the normal output of the power amplifier. When the circuit output is short-circuited / overloaded: When the output current I increases sharply, the voltage VR18 of the second resistor R18 rises rapidly (for example, VR18 = 0.5V when I = 5A). After the voltage of the second resistor R18 is superimposed on the voltage divided by the first resistor R20 / third resistor R28, the base potential of the first transistor Q1 is 0.6V - 0.7V higher than the emitter potential. The first transistor Q1 changes from off to on. After the first transistor Q1 is on, the base of the second transistor Q2 is pulled low, and the second transistor Q2 changes from off to on. The emitter of the second transistor Q2 is connected to the power supply terminal (corresponding to +PWVS), and the collector is grounded through the fifth resistor R26 / sixth resistor R27. When it is on, it will shunt the current from +PWVS to ground, lowering the supply voltage of the first transistor Q1, and indirectly limiting the output current. Meanwhile, the PROR terminal of the main control module MCU can be connected to turn off the power amplifier according to the change in the collector voltage level of the second transistor Q2; among them, the Zener diode Z2 (3.3V Zener diode) provides a reference voltage to the base of the second transistor Q2 through the fifth resistor R26-the seventh resistor R27, ensuring that the conduction threshold of the second transistor Q2 is stable and not affected by the +PWVS voltage fluctuation; The circuit described above outputs four audio signals. This description covers one of the four channels, while the other three are described in the same way. If the design involves more than four audio outputs, these channels can be stacked to form a multi-channel protection circuit. Fast-response overcurrent protection: The response time from the occurrence of overcurrent to the execution of protection action is short. When an overcurrent occurs in the downstream load, the voltage change on the second resistor R18 can be quickly transmitted to the base-emitter circuit of the first transistor Q1, causing the first transistor Q1 to quickly change its conduction state and limit or cut off the output current in time. This can effectively avoid permanent damage to key audio equipment components such as power amplifiers due to excessive overcurrent duration, thus improving the safety and reliability of the equipment. Precise overcurrent threshold control: By appropriately selecting the resistance values ​​of components such as the first resistor R20, the second resistor R18, and the third resistor R28, the overcurrent protection threshold can be precisely set. The circuit component parameters can be flexibly adjusted according to parameters such as the rated current of different audio equipment amplifiers, ensuring that the overcurrent protection circuit meets the normal operating current requirements of the equipment while accurately triggering protection against abnormal overcurrent conditions, avoiding false tripping and missed tripping. Stable operating characteristics: Under varying power supply voltage inputs (such as +PWVS voltage fluctuating within a certain range) and load changes, the auxiliary circuit composed of the second transistor Q2 and components such as the Zener diode can stabilize the operating point of the first transistor Q1, ensuring that the overcurrent protection circuit always operates reliably. Even in complex audio equipment operating environments (such as those with electromagnetic interference and power supply ripple), this circuit can maintain stable protection performance and will not fail or falsely trigger due to external interference. In some audio devices, especially high-end HiFi audio, overcurrent protection circuits should not cause significant distortion or interference to the audio signal. Some overcurrent protection schemes using active circuits may introduce additional noise, harmonics, etc., affecting the purity of the audio signal and reducing sound quality. This circuit does not have such problems.

[0023] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. An audio signal overcurrent protection circuit, characterized in that, have: The main control module is used to output at least one power amplifier signal; At least one switching module, whose first signal input terminal is connected to the output terminal of the main control module, is used to receive the power amplifier signal. The second signal input terminal of the switch module is connected to the power supply terminal; The current limiting module has its first signal input terminal connected to the second signal input terminal of the switching module. The second signal input terminal of the current limiting module is connected to the power supply terminal. The output terminal of the current limiting module is connected to one input terminal of the main control module to obtain a level signal; When the input power amplifier signal is greater than the preset value of the switching module, the switching module is controlled to turn on, thereby triggering the current limiting module to turn on. The main control module stops outputting the power amplifier signal according to the level signal status output by the current limiting module.

2. The audio signal overcurrent protection circuit according to claim 1, characterized in that, The switch module includes a first branch, a second branch, a third branch, and a fourth branch connected in parallel. The first signal input terminals of the first branch, the second branch, the third branch, and the fourth branch are connected to the output terminal of the main control module. The second signal input terminals of the first branch, the second branch, the third branch, and the fourth branch are connected to the power supply terminal; The second signal input terminals of the first branch, the second branch, the third branch, and the fourth branch are also connected to the first signal input terminal of the current limiting module.

3. The audio signal overcurrent protection circuit according to claim 2, characterized in that, The first branch includes a first transistor, a first resistor, a second resistor, and a third resistor. The base of the first transistor is connected to one end of the first resistor and one end of the third resistor. The collector of the first transistor is connected to the first signal input terminal of the current limiting module. The collector of the first transistor is connected to the power supply terminal through a fourth resistor. The other end of the first resistor and one end of the second resistor are respectively connected to the output terminal of the main control module. The other end of the second resistor and the other end of the third resistor are respectively connected to the emitter of the first transistor.

4. The audio signal overcurrent protection circuit according to claim 3, characterized in that, The first transistor is selected as an NPN transistor.

5. The audio signal overcurrent protection circuit according to claim 3, characterized in that, The current limiting module includes at least a second transistor and a fifth resistor. The base of the second transistor is connected to the collector of the first transistor. The emitter of the second transistor is connected to the power supply terminal. The collector of the second transistor is connected to one end of the fifth resistor. The other end of the fifth resistor is coupled to an input terminal of the main control module.

6. The audio signal overcurrent protection circuit according to claim 5, characterized in that, The current limiting module also includes a Zener diode and a sixth resistor connected in parallel. The cathode of the Zener diode and one end of the sixth resistor are respectively connected to an input terminal of the main control module. The anode of the Zener diode and the other end of the sixth resistor are respectively connected to the common terminal.

7. The audio signal overcurrent protection circuit according to claim 5, characterized in that, The second transistor is selected as a PNP type transistor.

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