Loudspeaker load protection circuit

Abstract

The utility model discloses a loudspeaker load protection circuit, which comprises an electronic switch module, a power detection module and a PWM (Pulse-Width Modulation) power regulation module, wherein the output end of the electronic switch module is electrically connected with the sampling input end of the power detection module, the output end of the power detection module is electrically connected with the input end of the PWM power regulation module, the output end of the PWM power regulation module is electrically connected with the second input end of the electronic switch module, and the first input end of the electronic switch module is externally connected with the output end of the power amplifier module. When the power detection module detects that the operation power of the loudspeaker exceeds a preset threshold value, the PWM power adjustment module controls the output energy by adjusting the duty ratio of the pulse signal, so that the energy output to the loudspeaker in unit time is controlled within the preset threshold value. The circuit protection is realized through the duty ratio adjustment mode, and the problem of sound interruption of the loudspeaker caused by open circuit is avoided while the circuit protection is completed.

Description

TECHNICAL FIELD

[0001] The utility model belongs to loudspeaker load protection technical field, specifically relates to a loudspeaker load protection circuit. BACKGROUND

[0002] When the sound system is used, the speaker box is often damaged. After the speaker box is damaged, the matching power amplifier is also damaged sometimes, and the device is easily burned, which is very dangerous. The speaker box is damaged for many reasons, for example, the matching power amplifier of the speaker box has large output power, or the power amplifier greatly exceeds the rated output power under abnormal conditions such as microphone howling, resulting in damage to the speaker box.

[0003] Therefore, the existing loudspeaker device usually increases a load protection module in the circuit to prevent the short-time excessive power input from causing the loudspeaker to burn out.

[0004] At present, the load protection module in the existing loudspeaker is usually realized by connecting a protection unit in series in the circuit, such as a voltage dividing element or a cut-off switch. Some speaker boxes on the market implement series bulb protection for high-frequency loudspeakers. However, the bulb is often burned out due to heat. It is difficult to implement series bulb protection for low-frequency loudspeakers because the power that the low-frequency loudspeaker bears is much larger than that of the high-frequency loudspeaker, and the power of the bulb during protection is very large, and the power consumption of the bulb when the loudspeaker is not overloaded is very small, so it is difficult to find a matching bulb. Some speaker boxes are connected in series with a fuse or a recoverable fuse, a relay, etc. to implement protection. The fuse will be fused when it reaches a certain temperature, causing the circuit to be disconnected. The protection form using a relay will actively protect the loudspeaker unit by disconnecting the circuit when the received input power exceeds the preset threshold. As can be seen, the existing various protection forms, whether passive protection by voltage dividing element or active protection by relay cut-off switch, may eventually cause the disconnection of the overall circuit, and even if the circuit is automatically restored, there will be a short-term disconnection. The disconnection of the circuit means that the input sound cannot be amplified and processed. This means that there will be no sound from the speaker box for a short period of time after protection, which is unacceptable.

[0005] Therefore, there is an urgent need to provide a loudspeaker load protection circuit that can complete circuit protection without causing the disconnection problem and resulting in the interruption of loudspeaker sound. UTILITY MODEL CONTENTS

[0006] The utility model aims at providing a loudspeaker load protection circuit to solve the above problems existing in the prior art.

[0007] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0008] The utility model provides a loudspeaker load protection circuit, wherein it comprises:

[0009] An electronic switch module, a power detection module and a PWM power regulation module are included.

[0010] The output end of the electronic switch module is electrically connected to the sampling input end of the power detection module, the output end of the power detection module is electrically connected to the input end of the PWM power regulation module, the output end of the PWM power regulation module is electrically connected to the second input end of the electronic switch module, and the output end of the electronic switch module is also electrically connected to the input end of the loudspeaker, and the first input end of the electronic switch module is externally connected to the power amplifier module.

[0011] In a possible design, the electronic switch module comprises a first MOS tube and a second MOS tube.

[0012] The output end of the power amplifier module is electrically connected to the drain of the first MOS tube, the source of the first MOS tube is electrically connected to the source of the second MOS tube, and the drain of the second MOS tube is electrically connected to the sampling input end of the power detection module.

[0013] The gate of the first MOS tube and the gate of the second MOS tube are both electrically connected to the output end of the PWM power regulation module, and the drain of the second MOS tube is also electrically connected to the input end of the loudspeaker.

[0014] In a possible design, the first MOS tube and the second MOS tube are both enhancement mode MOS tubes.

[0015] In a possible design, the electronic switch module further comprises a battery unit.

[0016] The power supply end of the battery unit is respectively electrically connected to the gate of the first MOS tube and the gate of the second MOS tube.

[0017] In a possible design, the battery unit comprises a lithium battery assembly.

[0018] The power supply end of the lithium battery assembly is respectively electrically connected to the gate of the first MOS tube and the gate of the second MOS tube.

[0019] In a possible design, the battery unit further comprises a photovoltaic battery assembly.

[0020] The power supply end of the photovoltaic battery assembly is respectively electrically connected to the gate of the first MOS tube and the gate of the second MOS tube.

[0021] In a possible design, a first filter module is further included.

[0022] The output end of the power amplifier module is electrically connected with the input end of the first filter module, and the output end of the first filter module is electrically connected with the sampling input end of the power detection module.

[0023] In a possible design, the first filter module comprises a first capacitor and a first resistor.

[0024] One end of the first resistor is electrically connected with the output end of the power amplifier module, the other end of the first resistor is electrically connected with one end of the first capacitor, and the other end of the first capacitor is electrically connected with the sampling input end of the power detection module.

[0025] In a possible design, the power detection module and the PWM power regulation module both comprise an MCU.

[0026] Beneficial effects: the utility model provides a loudspeaker load protection circuit, including electronic switch module, power detection module and PWM power regulation module, wherein, the output end of electronic switch module is electrically connected with the sampling input end of power detection module, the output end of power detection module is electrically connected with the input end of PWM power regulation module, the output end of PWM power regulation module is electrically connected with the second input end of electronic switch module, and the output end of power amplifier module is externally connected with the first input end of electronic switch module. When the power detection module detects that the operating power of the loudspeaker exceeds the preset threshold, the power detection module will send the overvoltage signal to the PWM power regulation module, and the PWM power regulation module will control the output energy by adjusting the duty cycle of the pulse signal, so as to control the energy output to the loudspeaker in unit time within the preset threshold. The utility model replaces the existing circuit breaking regulation mode by this duty cycle regulation mode, limits the maximum current output to the loudspeaker in unit time, but does not break the circuit, so that the loudspeaker sound interruption problem caused by the circuit breaking is avoided while the circuit protection is completed. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 It is a functional structure block diagram of the loudspeaker load protection circuit in the utility model embodiment 1.

[0028] Figure 2 It is a circuit diagram of the loudspeaker load protection circuit in the utility model embodiment 2.

[0029] Figure 3 It is a functional structure block diagram of the battery unit power supply circuit in the utility model embodiment 2.

[0030] The components include: 1. Power amplifier module; 2. Electronic switch module; 3. Power detection module; 4. PWM power adjustment module; 5. First MOSFET; 6. Second MOSFET; 7. First diode; 8. Second diode; 9. First capacitor; 10. First resistor; and 11. Speaker. Detailed Implementation

[0031] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the present utility model will be briefly introduced below in conjunction with the accompanying drawings and descriptions of the embodiments or the prior art. Obviously, the following description of the structure of the accompanying drawings is only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. It should be noted that the description of these embodiments is used to help understand this utility model, but does not constitute a limitation on this utility model.

[0032] It should be understood that although the terms first, second, etc., may be used herein to describe various units, these units should not be limited by these terms. These terms are only used to distinguish one unit from another. For example, the first unit may be referred to as the second unit, and similarly, the second unit may be referred to as the first unit, without departing from the scope of the exemplary embodiments of this utility model.

[0033] It should be understood that the term "and / or" that may appear in this document is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist simultaneously. The term " / and" that may appear in this document describes another relationship between related objects, indicating that two relationships can exist. For example, A / and B can mean: A exists alone, and A and B exist alone. In addition, the character " / " that may appear in this document generally indicates that the related objects before and after it are in an "or" relationship.

[0034] Example 1:

[0035] like Figure 1 As shown, this embodiment provides a speaker load protection circuit, including: an electronic switch module 2, a power detection module 3, and a PWM power adjustment module 4;

[0036] Wherein, the output end of the electronic switch module 2 is electrically connected to the sampling input end of the power detection module 3, the output end of the power detection module 3 is electrically connected to the input end of the PWM power regulation module 4, the output end of the PWM power regulation module 4 is electrically connected to the second input end of the electronic switch module 2, and the output end of the electronic switch module 2 is also electrically connected to the input end of the loudspeaker 11, and the first input end of the electronic switch module 2 is externally connected with the power amplifier module 1.

[0037] The electronic switch module 2, the power detection module 3 and the PWM power regulation module 4 are arranged between the power amplifier module 1 and the loudspeaker 11. When the gate voltage of the electronic switch module 2 is 0, the electronic switch module 2 is in an open circuit state. When the loudspeaker 11 is in a normal state, the PWM regulation module normally provides a voltage to the second input end of the electronic switch module 2, so that the electronic switch module 2 is turned on. At this time, the power of the power amplifier module 1 can normally supply the loudspeaker 11. When the power detection module 3 detects that the running power of the loudspeaker 11 exceeds a preset threshold, the power detection module 3 sends an overvoltage signal to the PWM power regulation module 4. The PWM power regulation module 4 adjusts the duty cycle (i.e. the ratio of pulse width to the whole period) of the pulse signal to control the output level, thereby realizing the adjustment of the output frequency and controlling the frequency at which the electronic switch module 2 is turned on. Thus, the power output to the loudspeaker 11 per unit time is controlled within the preset threshold.

[0038] That is, in the loudspeaker load protection circuit of the embodiment, the on-off ratio of the audio signal per unit time is adjusted to replace the existing open circuit regulation. The protection function is to limit the maximum current output to the loudspeaker 11 per unit time, thereby preventing the loudspeaker 11 unit from being burned out due to excessive power. Since the on-off ratio is only adjusted to control the change of the output frequency, the open circuit condition will not occur. In the specific implementation, since the human hearing range is 20HZ-20kHz, and the sampling frequency is 44.1kHz (Nyquist sampling theorem: in order to accurately restore the original signal, the sampling frequency must be at least twice the highest frequency of the signal. Therefore, for a maximum audible frequency of 20kHz, the theoretical sampling frequency should reach 40kHz. However, in order to leave a margin and ensure signal quality, the actual sampling frequency will be higher. In this embodiment, 44.1kHz is used.), the turn-on frequency of the electronic switch module 2 is kept in the interval higher than 44.1kHz. Therefore, the loudspeaker load protection circuit in this embodiment protects the circuit while not affecting the normal use of the loudspeaker 11, ensuring the sound quality of the loudspeaker 11.

[0039] Embodiment 2:

[0040] AsFigure 2 , Figure 3 As shown, this embodiment provides a speaker load protection circuit. In one possible implementation, the electronic switch module 2 includes a first MOSFET 5 and a second MOSFET 6.

[0041] In this configuration, the output terminal of the power amplifier module 1 is electrically connected to the drain of the first MOSFET 5, the source of the first MOSFET 5 is electrically connected to the source of the second MOSFET 6, the gate of the first MOSFET 5 is electrically connected to the output terminal of the PWM power adjustment module 4, the drain of the second MOSFET 6 is electrically connected to the sampling input terminal of the power detection module 3, and the gate of the second MOSFET 6 is electrically connected to the output terminal of the PWM power adjustment module 4.

[0042] Because the current between the output terminal of the power amplifier module 1 and the input terminal of the speaker 11 is alternating current, when the first MOSFET 5 and the second MOSFET 6 are turned off, there will still be current from their source to their drain. Therefore, connecting the sources of the first MOSFET 5 and the second MOSFET 6 can ensure that the two MOSFETs can be completely turned off.

[0043] In the path between the electronic switch module 2 and the power detection module 3, a filter circuit can also be set to filter out the high-frequency pulses sent by the electronic switch module 2 to ensure the correct power sampling value.

[0044] In one possible implementation, both the first MOSFET 5 and the second MOSFET 6 are enhancement-mode MOSFETs.

[0045] It should be noted that, to ensure that the electronic switch module 2 is conducting in the initial state, the first MOSFET 5 and the second MOSFET 6 should be depletion-type MOSFETs. However, there are too few types of depletion-type MOSFETs on the market (the mainstream MOSFETs on the market are enhancement-type), so enhancement-type MOSFETs are selected here.

[0046] When an enhancement-type MOSFET is selected, electronic switch module 2 can draw power from the output (audio signal) of power amplifier module 1 (see [link]). Figure 3 The power conversion module in the amplifier module (in the power conversion module) is used because the bias voltage required for the enhancement-mode MOSFET to turn on is very small. As long as the audio signal output by the power amplifier module 1 is greater than 1 volt, and the voltage is boosted to 5 volts through the boost circuit, the enhancement-mode MOSFET will turn on.

[0047] In one possible implementation, the electronic switch module 2 further includes a battery unit;

[0048] The power supply terminals of the battery cells are electrically connected to the gates of the first MOS transistor 5 and the second MOS transistor 6, respectively.

[0049] In one possible implementation, the battery cell includes a lithium battery assembly;

[0050] The power supply end of the lithium battery assembly is electrically connected to the gate of the first MOS tube 5 and the second MOS tube 6 respectively.

[0051] In a possible implementation, the battery unit further comprises a photovoltaic battery assembly.

[0052] The power supply end of the photovoltaic battery assembly is electrically connected to the gate of the first MOS tube 5 and the second MOS tube 6 respectively.

[0053] The battery unit mentioned herein refers to the voltage distribution module in the Figure 3 The voltage distribution module has two main functions: the first is to distribute energy to the enhancement mode MOS tube as a bias voltage, ensuring that the first MOS tube 5 and the second MOS tube 6 are initially turned on, allowing the speaker to produce sound normally; the second is to supply power to the MCU and its peripheral circuits, and provide different power supply voltages according to the needs of different circuits.

[0054] It should be noted that when using a lithium battery assembly to bias the enhancement mode MOS tube, the enhancement mode MOS tube is initially turned on, and then the audio signal output from the power amplifier module 1 is used to charge the lithium battery assembly to supplement energy; when using a photovoltaic battery assembly to bias the enhancement mode MOS tube, the enhancement mode MOS tube is initially turned on. When the indoor light is dark and the output voltage of the photovoltaic battery assembly is low, the voltage can be boosted by the boost circuit to turn on the enhancement mode MOS tube. Power can be taken from the output end of the power amplifier module 1 and through the battery unit, which can be selected according to actual needs (corresponding to the setting of the power conversion circuit and the voltage distribution circuit).

[0055] In addition, the electronic switch module 2 can further include a first diode 7 and a second diode 8, both of which are parasitic diodes.

[0056] The source of the first MOS tube 5 is electrically connected to the input end of the first diode 7, the output end of the first diode 7 is electrically connected to the drain of the first MOS tube 5, the source of the MOS tube is electrically connected to the input end of the second diode 8, and the output end of the second diode 8 is electrically connected to the drain of the second MOS tube 6.

[0057] When the gates of the first MOS tube 5 and the second MOS tube 6 are disconnected, due to the presence of the first diode 7 and the second diode 8, the current can still flow in one direction in the first diode 7 and the second diode 8.

[0058] And, the first MOS tube 5 and the second MOS tube 6 can also be replaced by a MOS tube without a parasitic diode, such as a gallium nitride MOS tube, that is, a gallium nitride MOS tube without a parasitic diode can replace the two silicon MOS tubes with parasitic diodes in the embodiment.

[0059] In a possible implementation, the first filter module is further included;

[0060] The output end of the power amplifier module 1 is electrically connected to the input end of the first filter module, and the output end of the first filter module is electrically connected to the sampling input end of the power detection module 3.

[0061] In a possible implementation, the first filter module includes a first capacitor 9 and a first resistor 10.

[0062] One end of the first resistor 10 is electrically connected to the output end of the power amplifier module 1, the other end of the first resistor 10 is electrically connected to one end of the first capacitor 9, and the other end of the first capacitor 9 is electrically connected to the sampling input end of the power detection module 3.

[0063] Since the loudspeaker 11 is an inductive load, an induced voltage is generated in the circuit after the current flows through the loudspeaker 11, and the induced voltage generated by the loudspeaker 11 can be effectively eliminated by setting the first filter module (that is, the RC filter circuit).

[0064] In a possible implementation, the second filter module is further included.

[0065] The output end of the power amplifier module 1 is electrically connected to the input end of the second filter module, and the output end of the second filter module is electrically connected to the sampling input end of the power detection module 3. The output end of the electronic switch module 2 is electrically connected to the input end of the second filter module, and the output end of the second filter module is electrically connected to the sampling input end of the power detection module 3.

[0066] The second filter module functions to filter the high-frequency pulse sent by the electronic switch module through an RC filter circuit (including a voltage dividing resistor and a filter capacitor), so as to ensure correct power sampling values.

[0067] In a possible implementation, the power detection module 3 and the PWM power regulation module 4 each include an MCU.

[0068] In a possible implementation, the power detection module 3 includes a voltage detection unit and a current detection unit.

[0069] In a possible implementation, if the loudspeakers 11 in the sound box are divided into two loudspeakers 11 of high pitch and low pitch, or multiple loudspeakers 11, each loudspeaker 11 can use an electronic switch module 2 to realize protection, or multiple loudspeakers 11 can share one electronic switch module 2.

[0070] Finally, it should be noted that: the above only for the preferred embodiments of the present application, and is not intended to limit the scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included within the scope of the present application.

Claims

1. A loudspeaker load protection circuit, characterized in that, comprising: an electronic switch module (2), a power detection module (3) and a PWM power regulation module (4); wherein the output end of the electronic switch module (2) is electrically connected to the sampling input end of the power detection module (3), the output end of the power detection module (3) is electrically connected to the input end of the PWM power regulation module (4), the output end of the PWM power regulation module (4) is electrically connected to the second input end of the electronic switch module (2), and the output end of the electronic switch module (2) is also electrically connected to the input end of the loudspeaker (11), and the first input end of the electronic switch module (2) is externally connected with the power amplifier module (1).

2. The loudspeaker load protection circuit according to claim 1, characterized in that, the electronic switch module (2) comprises a first MOS tube (5) and a second MOS tube (6); wherein the output end of the power amplifier module (1) is electrically connected to the drain of the first MOS tube (5), the source of the first MOS tube (5) is electrically connected to the source of the second MOS tube (6), and the drain of the second MOS tube (6) is electrically connected to the sampling input end of the power detection module (3); the gate of the first MOS tube (5) and the gate of the second MOS tube (6) are both electrically connected to the output end of the PWM power regulation module (4), and the drain of the second MOS tube (6) is also electrically connected to the input end of the loudspeaker.

3. The loudspeaker load protection circuit according to claim 2, characterized in that, the first MOS tube (5) and the second MOS tube (6) are both enhancement mode MOS tubes.

4. The loudspeaker load protection circuit according to claim 3, characterized in that, the electronic switch module (2) further comprises a battery unit; wherein the power supply end of the battery unit is electrically connected to the gate of the first MOS tube (5) and the gate of the second MOS tube (6) respectively.

5. The loudspeaker load protection circuit according to claim 4, characterized in that, the battery unit comprises a lithium battery assembly; wherein the power supply end of the lithium battery assembly is electrically connected to the gate of the first MOS tube (5) and the gate of the second MOS tube (6) respectively.

6. The loudspeaker load protection circuit according to claim 5, characterized in that, the battery unit further comprises a photovoltaic battery assembly; wherein the power supply end of the photovoltaic battery assembly is electrically connected to the gate of the first MOS tube (5) and the gate of the second MOS tube (6) respectively.

7. The loudspeaker load protection circuit according to claim 1, characterized in that, further comprising a first filter module; wherein the output end of the power amplifier module (1) is electrically connected to the input end of the first filter module, and the output end of the first filter module is electrically connected to the sampling input end of the power detection module (3).

8. The loudspeaker load protection circuit according to claim 7, characterized in that, the first filter module comprises a first capacitor (9) and a first resistor (10); One end of the first resistor (10) is electrically connected to the output end of the power amplifier module (1), the other end of the first resistor (10) is electrically connected to one end of the first capacitor (9), and the other end of the first capacitor (9) is electrically connected to the sampling input end of the power detection module (3).

9. The loudspeaker load protection circuit of claim 1, wherein, The power detection module (3) and the PWM power regulation module (4) each include an MCU.

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