CN115103272B

CN115103272B - Mute control method, audio power amplifier circuit and audio power amplifier chip

Info

Publication number: CN115103272B
Application number: CN202211015947.0A
Authority: CN
Inventors: 刘彬; 李瑞平
Original assignee: Shanghai Xinlong Semiconductor Technology Co ltd Nanjing Branch
Current assignee: Shanghai Xinlong Semiconductor Technology Co ltd Nanjing Branch
Priority date: 2022-08-24
Filing date: 2022-08-24
Publication date: 2022-12-02
Anticipated expiration: 2042-08-24
Also published as: CN115103272A

Abstract

The invention provides a mute control method, an audio power amplifier circuit and an audio power amplifier chip. The mute control method comprises the following steps: judging a discharging loop corresponding to residual charge of the loudspeaker based on the instantaneous current of the loudspeaker; within a first preset time period, conducting the corresponding discharge loop and driving the loudspeaker to discharge with preset current; and after the first preset time period, outputting a control signal to drive the difference value between the current of the loudspeaker and the mute current to be within a preset range. Corresponding control modules are arranged in the audio power amplifier circuit and the audio power amplifier chip so as to realize the mute control method. By the configuration, residual charges in the loudspeaker are eliminated by discharging, noise is ensured not to be generated at the moment of mute switching, and the judgment of the discharging loop is carried out by instantaneous current, so that extra control risks of incapability of discharging or short circuit of an internal circuit and the like are avoided, and the problems in the prior art are solved.

Description

Mute control method, audio power amplifier circuit and audio power amplifier chip

Technical Field

The invention relates to the field of audio signal processing, in particular to a mute control method, an audio power amplifier circuit and an audio power amplifier chip.

Background

The audio power amplifier is commonly used in the fields of car audio, home theater, stage audio and the like, the driving current, the output power, the total harmonic distortion and the like of the audio power amplifier are important parameter indexes of the audio power amplifier, but the indexes of silence, standby and the like are also one of the performances of embodying the audio power amplifier; if the muting function of the audio power amplifier is not good, there may be a problem that the audio power amplifier cannot be muted completely or has a "click" sound instantly after muting.

In summary, in the prior art, there is a problem that the speaker is prone to generate a "pulh" sound at the moment the audio power amplifier is switched to the mute function, and the user experience is affected.

Disclosure of Invention

The invention aims to provide a mute control method, an audio power amplifier circuit and an audio power amplifier chip, and solve the problems that at the moment when an audio power amplifier is switched to a mute function, a loudspeaker is prone to generating 'pulverary' sound and user experience is influenced in the prior art.

In order to solve the above technical problem, according to a first aspect of the present invention, there is provided a mute control method comprising the steps of: receiving a mute setting signal; measuring an instantaneous current of a speaker directly or indirectly while receiving the mute setting signal; judging a discharging loop corresponding to the residual charge of the loudspeaker based on the instantaneous current; the discharge circuit includes: a positive discharge loop and a negative discharge loop; within a first preset time, conducting the corresponding discharge loop and driving the loudspeaker to discharge at a preset current, wherein the preset current is smaller than the normal working current of the loudspeaker; and after the first preset time period, outputting a control signal to drive the difference value between the current of the loudspeaker and the mute current to be within a preset range.

In order to solve the above technical problem, according to a second aspect of the present invention, an audio power amplifier circuit is provided, where the audio power amplifier circuit includes a control module, and the control module is configured to execute the foregoing mute control method.

Optionally, the audio power amplifier circuit further includes an audio signal amplifier, a driving module, an upper power tube and a lower power tube.

The audio signal amplifier comprises an audio signal positive phase end and an audio signal negative phase end, and is used for outputting signals based on the pressure difference between the audio signal positive phase end and the audio signal negative phase end.

The input end of the driving module is connected with the output end of the audio signal amplifier, and the driving module is used for controlling the upper power tube and the lower power tube to work based on the received signals.

The anode of the upper power tube is used for being connected with the anode of an external power supply, the cathode of the upper power tube is connected with the anode of the lower power tube, and the cathode of the lower power tube is used for being connected with the cathode of the external power supply.

And the cathode of the upper power tube is used for providing working current of the loudspeaker.

The upper power tube is used for forming the positive discharging loop, and the lower power tube is used for forming the negative discharging loop.

Optionally, the audio power amplifier circuit further includes a mute function locking module, the control module includes a first port, and an output end of the mute function locking module is connected to the first port.

When the mute function locking module does not output the mute setting signal, the mute function locking module outputs the mute setting signal only when the voltage of the input end of the mute function locking module is greater than a first preset voltage.

When the mute function locking module outputs the mute setting signal, the mute function locking module does not output the mute setting signal only when the voltage of the input end of the mute function locking module is less than a second preset voltage.

The first preset voltage is greater than the second preset voltage.

Optionally, the control module includes a second port, the second port is used for directly or indirectly measuring the instantaneous current of the loudspeaker, and the second port is connected with the negative electrode of the upper power tube.

Optionally, the control module includes a third port, and when receiving the mute setting signal, the third port is configured to output a first signal to the driving module, and when not receiving the mute setting signal, the third port is configured to output a second signal to the driving module.

When the first signal is received, the driving module works with a first amplification factor; and when the second signal is received, the driving module works with a second amplification factor, and the first amplification factor is smaller than the second amplification factor.

Optionally, the control module includes a fourth port, the fourth port is connected to the output end of the audio signal amplifier, the fourth port is configured to intervene in the output signal of the audio signal amplifier after the first preset time period, so that the input signal of the driving module is clamped to a mute value, and when the signal received by the driving module is the mute value, the driving module controls the difference between the current of the speaker and the mute current within a preset range.

Optionally, the control module includes a fifth port and a sixth port, the fifth port and the sixth port are respectively connected to one of the audio signal positive phase terminal and the audio signal negative phase terminal, and the fifth port and the sixth port are used for intervening in the input signal of the audio signal amplifier to realize: and within a first preset time period, conducting the corresponding discharge loop and driving the loudspeaker to discharge with preset current.

Optionally, the audio power amplifier circuit further includes at least one of an under-voltage protection module, an over-temperature protection module, and an over-current protection module.

The undervoltage protection module is used for delaying the control module and the driving module to start after a second preset time when the audio power amplifier circuit is powered on; the undervoltage protection module is also used for maintaining the working state of the driving module within a third preset time after the audio power amplifier circuit is powered off; the second preset duration and the third preset duration are set based on a noise triggering critical interval of the speaker.

The over-temperature protection module is used for selecting one of the following strategies according to the temperature of the audio power amplifier circuit: starting the driving module; the operation of the driving module is not interfered; reducing the output power of the driving module; and closing the driving module.

The overcurrent protection module is used for detecting peak current flowing through the upper power tube and the lower power tube, and when the peak current exceeds a safety range, the corresponding upper power tube or the corresponding lower power tube is closed in the current period.

In order to solve the above technical problem, according to a third aspect of the present invention, an audio power amplifier chip is provided, which includes the above audio power amplifier circuit.

Compared with the prior art, the mute control method, the audio power amplifier circuit and the audio power amplifier chip provided by the invention comprise the following steps: receiving a mute setting signal; measuring an instantaneous current of a speaker directly or indirectly while receiving the mute setting signal; judging a discharging loop corresponding to the residual charge of the loudspeaker based on the instantaneous current; the discharge circuit includes: a positive discharge loop and a negative discharge loop; within a first preset time, conducting the corresponding discharge loop and driving the loudspeaker to discharge at a preset current, wherein the preset current is smaller than the normal working current of the loudspeaker; and after the first preset time period, outputting a control signal to drive the difference value between the current of the loudspeaker and the mute current to be within a preset range. Corresponding control modules are arranged in the audio power amplifier circuit and the audio power amplifier chip so as to realize the mute control method. By the configuration, residual charges in the loudspeaker are eliminated through discharging, noise cannot be generated at the moment of mute switching, and meanwhile, the judgment of a discharging loop is carried out through instantaneous current, so that extra control risks such as incapability of discharging or short circuit of an internal circuit and the like are avoided, and the problems in the prior art are solved.

Drawings

It will be appreciated by those skilled in the art that the drawings are provided for a better understanding of the invention and do not constitute any limitation to the scope of the invention. Wherein:

fig. 1 is a flowchart illustrating a mute control method according to an embodiment of the present invention.

Fig. 2 is a schematic circuit diagram of an audio power amplifier circuit and an audio power amplifier chip according to an embodiment of the present invention.

Fig. 3 is a circuit diagram of a control module according to an embodiment of the invention.

Fig. 4 is a schematic diagram of external connection of the audio power amplifier circuit and the audio power amplifier chip powered by dual power supplies according to an embodiment of the present invention.

Fig. 5 is a schematic diagram of external connection of the audio power amplifier circuit and the audio power amplifier chip powered by a single power supply according to an embodiment of the present invention.

In the drawings:

1-a control module; 2-a driving module; 3-a mute function locking module; 31-a threshold setting unit; 4-undervoltage protection module; 5-an over-temperature protection module; 6-an overcurrent protection module; 7-bias voltage setting module; 10-a loudspeaker; 11-audio power amplifier circuit; 12-audio power amplifier chip.

Detailed Description

To further clarify the objects, advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is to be noted that the drawings are in simplified form and are not to scale, but are provided for the purpose of facilitating and clearly illustrating embodiments of the present invention. Further, the structures illustrated in the drawings are often part of actual structures. In particular, the drawings may have different emphasis points and may sometimes be scaled differently.

As used in this disclosure, the singular forms "a," "an," and "the" include plural referents, the term "or" is generally employed in a sense including "and/or," the terms "a," "an," and "the" are generally employed in a sense including "at least one," the terms "at least two" are generally employed in a sense including "two or more," and further, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to imply that the number of indicated technical features is essential. Thus, features defined as "first", "second" and "third" may explicitly or implicitly include one or at least two of the features, "one end" and "the other end" and "proximal end" and "distal end" generally refer to the corresponding two parts, which include not only the end points, but also the terms "mounted", "connected" and "connected" should be understood broadly, e.g., as being fixedly connected, detachably connected, or integrated; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. Furthermore, as used in the present invention, the disposition of an element with another element generally only means that there is a connection, coupling, fit or driving relationship between the two elements, and the connection, coupling, fit or driving relationship between the two elements may be direct or indirect through intermediate elements, and cannot be understood as indicating or implying any spatial positional relationship between the two elements, i.e., an element may be in any orientation inside, outside, above, below or to one side of another element, unless the content clearly indicates otherwise. The specific meanings of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.

The core idea of the invention is to provide a mute control method, an audio power amplifier circuit and an audio power amplifier chip, so as to solve the problems that at the moment when an audio power amplifier is switched to a mute function, a speaker is prone to generate a pulsatory sound and user experience is influenced in the prior art.

The following description refers to the accompanying drawings.

As shown in fig. 1, the present embodiment provides a mute control method, which includes the following steps:

s10 receives a mute setting signal.

S20 measures the instantaneous current of the speaker directly or indirectly while receiving the mute setting signal.

S30, judging a discharging loop corresponding to the residual charge of the loudspeaker based on the instantaneous current; the discharge circuit includes: a positive discharge loop and a negative discharge loop.

And S40, within a first preset time period, conducting the corresponding discharge loop and driving the loudspeaker to discharge at a preset current, wherein the preset current is smaller than the normal working current of the loudspeaker.

And S50, after the first preset time period, outputting a control signal to drive the difference value between the current of the loudspeaker and the mute current to be within a preset range.

In step S10, the specific format of the mute setting signal may be arbitrarily set. For example, a high signal.

When the mute setting signal is at a high level, in step S20, the time point of receiving the mute setting signal is the time point of receiving the rising edge. When the mute setting signal is a signal of another format, the time point of receiving the mute setting signal may also be determined according to common knowledge in the art. In step S20, information about the instantaneous current needs to be obtained, and the information may be the magnitude and direction of the instantaneous current (i.e. direct measurement), or other signals, such as: feedback voltage, etc., by which the magnitude and direction of the instantaneous current can be determined, or at least the direction of the instantaneous current can be determined (i.e., indirect measurement). The speaker is muted instantly when operating, and if the logic state inside the chip cannot be correctly determined, the correct control state cannot be implemented, so that a pulser sound is generated, and the speaker is broken or burned out. By directing the residual charge to flow out of the respective discharge path through step S40, the above phenomenon can be reduced or eliminated. Meanwhile, since the current has positive and negative characteristics when the speaker operates, the residual charge has two directions corresponding to the positive and negative currents, and thus, the positive and negative characteristics of the discharge circuit need to be determined. That is, the discharge circuit needs to be determined by the setting step S30. In this embodiment, the discharging loop of the residual charge caused by the negative current is determined as a positive discharging loop, and the discharging loop of the residual charge caused by the positive current is determined as a negative discharging loop.

In step S40, discharging is performed for the first preset time period, and the discharging current is controlled to be the preset current, so that discharging is performed controllably, and noise is prevented from being generated. The first preset time period is set according to the estimated value of the residual charge and the preset current, and ensures that the residual charge can be lower than a residual safety threshold value, or 0, before step S50 is executed.

After step S40 is performed, the subsequent mute function is implemented in step S50 until the mute setting signal disappears. The mute current is a current for making the speaker not generate sound, and may be set according to a specific working principle of the speaker, and in an embodiment, the mute current is 0A.

In the present embodiment, the concept of "actuation" is mentioned, and "actuation" should be understood as: the purpose of outputting the control signal is to achieve a desired purpose, but may not necessarily be achieved due to interference from other factors. For example, pressing the ignition button drives the vehicle on, but if there is no oil in the vehicle's fuel tank at that time, the vehicle will not start either. Therefore, whether a method conforms to the relevant description of the present application cannot be determined according to the operation result of the method, but should be determined according to the operation purpose of the method, and the following should be understood according to such idea.

Based on the foregoing mute control method, this embodiment further provides an audio power amplifier circuit 11, where the audio power amplifier circuit 11 includes a control module 1, and the control module 1 is configured to execute the foregoing mute control method.

It can be understood that the specific implementation manner of the control module 1, such as how many ports are provided, what each port functions, what each port is connected with other elements, and what the connection manner of internal elements is, can be set according to actual needs.

In a preferred embodiment, the audio power amplifier circuit 11 is shown in fig. 2.

The audio power amplifier circuit 11 includes the control module 1, an audio signal amplifier OP1, a driving module 2, an upper power tube Q51 and a lower power tube Q52.

Wherein the audio signal amplifier OP1 comprises an audio signal positive terminal (denoted by "+" in the figure) and an audio signal negative terminal (denoted by "-" in the figure), and the audio signal amplifier OP1 is configured to output a signal based on a voltage difference between the audio signal positive terminal and the audio signal negative terminal. The specific operation principle of the audio signal amplifier OP1 can be understood according to the common general knowledge in the art, and generally, the audio signal amplifier OP1 outputs signals in a linear manner, but it is not excluded that the audio signal amplifier OP1 outputs signals in other logics based on other design objectives under specific working conditions.

The audio signal amplifier OP1 receives an externally input audio signal through the first buffer B1 and the second buffer B2, and the audio signal is input through the IN + and IN-ports.

The input end of the driving module 2 is connected to the output end of the audio signal amplifier OP1, which may be directly connected or indirectly connected, and the driving module 2 is configured to control the operations of the upper power transistor Q51 and the lower power transistor Q52 based on the received signal. The basic control principle of the drive module 2 is as follows: when the input signal is positive, the output current controls the upper power tube Q51 to be opened, and when the input signal is negative, the output current controls the lower power tube Q52 to be opened. For safety, the logic for switching the coordination between Q51 and Q52 may be set according to different requirements, for example, a certain delay is set during the switching process, and the like.

The upper power transistor Q51 and the lower power transistor Q52 control the magnitude of the output current according to the input current, and other operating principles of the upper power transistor Q51 and the lower power transistor Q52 can be understood according to common knowledge in the art, and will not be described herein.

The positive pole of going up power tube Q51 is used for connecting the anodal VCC of external power source, go up power tube Q51's negative pole with power tube Q52's positive pole is connected down, power tube Q52's negative pole is used for connecting external power source negative pole VEE down.

GND in fig. 2 denotes a port for grounding.

And the cathode of the upper power tube Q51 is used for providing the working current of the loudspeaker. The negative pole of the upper power tube Q51 is configured as the working current OUTPUT terminal OUTPUT.

In this embodiment, the upper power transistor Q51 is used to form the positive discharge circuit, and the lower power transistor Q52 is used to form the negative discharge circuit. In other embodiments, a discharge circuit independent from Q51 and Q52 may be provided.

Since the external signal received by the audio power amplifier circuit 11 may fluctuate to some extent, preferably, the audio power amplifier circuit 11 further includes a mute function locking module 3, the control module 1 includes a first port P1, and an output end of the mute function locking module 3 is connected to the first port P1.

When the mute function lock module 3 does not output the mute setting signal (i.e., outputs a low level), the mute function lock module 3 outputs the mute setting signal (i.e., outputs a high level) only when the voltage at the input terminal of the mute function lock module 3 is greater than the first preset voltage VTH 1.

When the mute function locking module 3 outputs the mute setting signal (i.e. outputs a high level), the mute function locking module 3 does not output the mute setting signal (i.e. outputs a low level) only when the voltage at the input end of the mute function locking module 3 is less than a second preset voltage VTL1.

The first preset voltage VTH1 is greater than the second preset voltage VTL1. Specific values of the first preset voltage VTH1 and the second preset voltage VTL1 may be set according to actual needs, and are not described herein.

The input end of the MUTE function locking module 3 is configured to be a MUTE end MUTE, when the MUTE is suspended or grounded, the OFF state of the MUTE function is defaulted, the audio power amplifier outputs normally, the MUTE is connected with high voltage, and when the level amplitude is higher than VTH1, the ON state of the MUTE function is realized, the audio power amplifier MUTEs and does not output, after the MUTE function is started, only when the voltage of the MUTE function is close to VTL1, the MUTE function is turned OFF, namely, the voltage window of the MUTE is VTH1-VTL1, the purpose of increasing the window is to increase the anti-interference capability of the MUTE pin, and the reliability of the MUTE function is improved.

In an embodiment, the mute function locking module 3 includes a locking module comparator COMP1 and a threshold setting unit 31, and the above functions are implemented by the locking module comparator COMP1 and the threshold setting unit 31. The working principle of the threshold setting unit 31 is that when COMP1 outputs a low level, the threshold setting unit 31 outputs a voltage VTH1, and when COMP1 outputs a high level, the threshold setting unit 31 is triggered to output a voltage VTL1, so that the MUTE trigger voltage is correspondingly changed. It is understood that in other embodiments, the mute function lock module 3 may be configured based on other principles.

For the user, the muted port is the MUTE port, and for the control module 1, the muted port is the first port P1. The effect of the two is slightly different.

Further, the control module 1 includes a second port P2, the second port P2 is used for directly or indirectly measuring the instantaneous current of the loudspeaker 10 (in this embodiment, measuring by the output voltage, which is an indirect measurement manner), and the second port P2 is connected to the negative electrode of the upper power tube Q51.

Further, the control module 1 includes a third port P3, when receiving the mute setting signal, the third port P3 is configured to output a first signal to the driving module 2, and when not receiving the mute setting signal, the third port P3 is configured to output a second signal to the driving module 2. In this embodiment, the first signal is at a high level, and the second signal is at a low level, in other embodiments, the first signal and the second signal may also be set as needed.

When receiving the first signal, the driving module 2 works with a first amplification factor; when the second signal is received, the driving module 2 works with a second amplification factor, and the first amplification factor is smaller than the second amplification factor. In an embodiment, the first amplification factor is less than or equal to 1/5 of the second amplification factor. With such a configuration, the technical effect of "the preset current is smaller than the normal operating current of the speaker 10" in the mute control method is advantageously achieved.

Further, the control module 1 includes a fourth port P4, the fourth port P4 is connected to the output end of the audio signal amplifier OP1, the fourth port P4 is configured to intervene in the output signal of the audio signal amplifier OP1 after the first preset time period, so that the input signal of the driving module 2 is clamped to a mute value, when the signal received by the driving module 2 is the mute value, the driving module 2 controls a difference between the current of the speaker 10 and the mute current to be within a preset range, and in an embodiment, the current of the speaker 10 is controlled to be equal to the mute current. The mute value may be calculated by performing a back-stepping calculation according to a specific working principle of the speaker 10 and the driving module 2, and in an embodiment, the mute value is 0A. The preset range is an error allowable range which can prevent the human ear from hearing the noise.

The control module 1 further includes a fifth port P5 and a sixth port P6, and the fifth port P5 and the sixth port P6 are respectively connected to one of the audio signal positive phase terminal and the audio signal negative phase terminal. For example, in fig. 2, the fifth port P5 is connected to the inverting terminal of the audio signal, and the sixth port P6 is connected to the non-inverting terminal of the audio signal. The fifth port P5 and the sixth port P6 are used to intervene in the input signal of the audio signal amplifier OP1 to achieve: and within a first preset time period, conducting the corresponding discharge loop and driving the loudspeaker to discharge with preset current.

For example, at the moment when the MUTE function is turned ON, if the upper power transistor Q51 is in the ON state, the OUTPUT voltage is high, the sixth port P6 OUTPUTs a low level, the fifth port P5 OUTPUTs a high level, and at this time, the audio signal amplifier OP1 OUTPUTs a low level, so as to drive the lower power transistor Q52 to turn ON (currently, a certain time delay may be needed before turning ON, but this is automatically implemented by the internal logic of the driving module 2), and the small current discharges the speaker 10. Similarly, at the moment of turning ON the MUTE function, if the lower power transistor Q52 is in the ON state at this time, the OUTPUT voltage is low, the sixth port P6 OUTPUTs a high level, the fifth port P5 OUTPUTs a low level, and at this time, the audio signal amplifier OP1 module OUTPUTs a high level, so as to drive the upper power transistor Q51 to be turned ON, and a small current discharges the speaker 10.

The design mode of interfering signals of other elements through the fourth port P4, the fifth port P5 and the sixth port P6 is also beneficial to utilizing the existing audio power amplifier circuit. For example, the design cost is lower, the existing audio power amplifier circuit can be directly modified, and the manufacturing cost is reduced.

The specific implementation manner of the control module 1 may be set differently according to the above description, for example, implemented by using a programmable controller, a field programmable gate array, or the like. Preferably, the control module 1 implements the control logic in a hardware manner, and the specific internal structure thereof is shown in fig. 3.

The control module 1 comprises a first triode Q1, a second triode Q2, a third triode Q3, a fourth triode Q4, a fifth triode Q5, a sixth triode Q6, a seventh triode Q7, an eighth triode Q8, a ninth triode Q9, a thirteenth triode Q10, an eleventh triode Q11, a twelfth triode Q12, a thirteenth triode Q13, a fourteenth triode Q14, a fifteenth triode Q15, a sixteenth triode Q16, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a constant current source S1, a control module comparator COMP2, a bidirectional voltage regulator D1 and a delay capacitor C1.

The first triode Q1 is a PNP type triode, an emitting electrode of the first triode Q1 is used for being connected with an external power supply positive electrode VCC, and a base electrode of the first triode is connected with a collector electrode of the first triode.

The second triode Q2, the third triode Q3, the fourth triode Q4, the fifth triode Q5, the sixth triode Q6, the seventh triode Q7 and the eighth triode Q8 are PNP-type triodes, the bases of the second triode Q2, the third triode Q3, the fourth triode Q4, the fifth triode Q5, the sixth triode Q6, the seventh triode Q7 and the eighth triode Q8 are all connected with the base of the first triode Q1, and the emitters of the second triode Q2, the third triode Q3, the fourth triode Q4, the fifth triode Q5, the sixth triode Q6, the seventh triode Q7 and the eighth triode Q8 are all used for connecting the external power supply positive electrode VCC.

The ninth triode Q9 is an NPN-type triode, a collector of the ninth triode Q9 is connected to a collector of the first triode Q1 through the constant current source S1, an emitter of the ninth triode Q9 is used for grounding, and a base of the ninth triode Q9 is configured as the first port P1.

The first end of the first resistor R1 is used for grounding, and the second end of the first resistor R1 is connected with the collector electrode of the second triode Q2; a first end of the second resistor R2 is configured as the second port P2, and a second end of the second resistor R2 is grounded through the bidirectional regulator tube D1.

An inverting end of the control module comparator COMP2 is connected to the second end of the first resistor R1, and a positive end of the control module comparator COMP2 is connected to the second end of the second resistor R2.

The thirteenth polar tube Q10 is an NPN-type polar tube, a collector of the thirteenth polar tube Q10 is connected to a collector of the third polar tube Q3, a base of the thirteenth polar tube Q10 is connected to an output end of the control module comparator COMP2, and an emitter of the thirteenth polar tube Q10 is used for grounding.

A first end of the third resistor R3 is connected to the collector of the thirteenth pole tube Q10, a second end of the third resistor R3 is connected to the emitter of the thirteenth pole tube Q10, and the collector of the thirteenth pole tube Q10 is configured as the sixth port P6.

The eleventh triode Q11 is an NPN-type triode, a collector of the eleventh triode Q11 is connected with a collector of the fourth triode Q4, and an emitter of the eleventh triode Q11 is used for grounding.

A first end of the fourth resistor R4 is connected to a collector of the eleventh transistor Q11, a second end of the fourth resistor R4 is connected to an emitter of the eleventh transistor Q11, and a collector of the eleventh transistor Q11 is configured as the fifth port P5.

The twelfth triode Q12 is an NPN-type triode, a base of the twelfth triode Q12 is connected to a collector of the first triode Q1, a collector of the twelfth triode Q12 is connected to a collector of the fifth triode Q5, and an emitter of the twelfth triode Q12 is used for grounding.

A first end of the delay capacitor C1 is connected to a collector of the fifth triode Q5, and a second end of the delay capacitor C1 is connected to an emitter of the twelfth triode Q12.

The thirteenth triode Q13 is an NPN-type triode, a base of the thirteenth triode Q13 is connected to a collector of the fifth triode Q5, a collector of the thirteenth triode Q13 is connected to a collector of the sixth triode Q6, and an emitter of the thirteenth triode Q13 is used for grounding.

The fourteenth triode Q14 is an NPN-type triode, a collector of the fourteenth triode Q14 is connected to a collector of the seventh triode Q7, the collector of the fourteenth triode Q14 is configured as the third port P3, a base of the fourteenth triode Q14 is connected to a collector of the sixth triode Q6, and an emitter of the fourteenth triode Q14 is configured to be grounded.

A first end of the fifth resistor R5 is connected to a collector of the seventh triode Q7, and a second end of the fifth resistor R5 is used for grounding.

The fifteenth triode Q15 is an NPN-type triode, a collector of the fifteenth triode Q15 is connected to a collector of the eighth triode Q8, a base of the fifteenth triode Q15 is connected to a collector of the sixth triode Q6, and an emitter of the fifteenth triode Q15 is used for grounding.

The sixteenth triode Q16 is an NPN-type triode, a base of the sixteenth triode Q16 is connected to the collector of the eighth triode Q8, an emitter of the sixteenth triode Q16 is used for grounding, and the collector of the sixteenth triode Q16 is configured as the fourth port.

A first end of the sixth resistor R6 is connected to a collector of the sixteenth triode Q16, and a second end of the sixth resistor R6 is used for grounding.

Based on the above connection relationship, the operating principle of the control module 1 is as follows: when the first port P1 is at a high level, Q9 is turned on, the constant current source S1 is turned on, and a stable current value is increased for I1 and I2 through the current mirror, a voltage drop generated by I1 and R1 is V1, that is, V1= I1 × R1, and a voltage at the reverse end of COMP2 is V1+ VGND; VGND is the voltage of ground pole, and is relevant with the external connection of audio power amplifier circuit. D1 connected with the same-direction end is a bidirectional voltage-stabilizing tube, the clamping value of the bidirectional voltage-stabilizing tube is higher than V1, and the amplitude of the OUTPUT signal is prevented from exceeding the working voltage of COMP2 (in order to reduce power consumption, a logic module inside a chip usually adopts low-voltage power supply), so that the COMP2 can normally detect the state of OUTPUT no matter a single power supply or double power supplies are connected.

At the moment of turning ON the MUTE function, if the upper power tube Q51 is turned ON at this time, the OUTPUT voltage is high, the COMP2 same-direction end voltage is higher than the reverse-direction end voltage, and a high level is OUTPUT, then Q10 is turned ON, the sixth port P6 is at a low level, Q11 is turned off, the fifth port P5 is at a high level, at this time, OP1 OUTPUTs a low level, the lower power tube Q52 is turned ON, and a small current discharges the speaker 10. Similarly, at the moment of the MUTE function ON, if the lower power tube Q52 is turned ON at this time, the OUTPUT voltage is low, the Q10 is turned off, the sixth port P6 is at a high level, the Q11 is turned ON, the fifth port P5 is at a low level, at this time, the core OP1 OUTPUTs a high level, the upper power tube Q51 is turned ON, and a small current discharges the speaker 10.

When the first port P1 is at a high level, a point a is at a low level, at this time, Q12 is turned off, I2 charges C1, after a delay time t (in this embodiment, t =0.1 s), a point B is at a high level, the fourth port P4 outputs a low level, and the output end of OP1 is clamped to GND, so that it is ensured that an audio signal is not output to the driving module 2; meanwhile, the third port P3 outputs a high level, so as to reduce the driving capability of the driving module 2.

The resistors R3, R4, R5 and R6 are pull-down resistors, and after the S1 constant current source is disconnected, the ports 3-6 are defaulted to GND; meanwhile, the resistance value of R6 is larger, and the amplitude of an output signal of the OP1 module cannot be influenced.

Referring to fig. 2, the audio power amplifier circuit 11 further includes an undervoltage protection module 4, an over-temperature protection module 5, and an over-current protection module 6. In other embodiments, a part of the undervoltage protection module 4, the over-temperature protection module 5, and the over-current protection module 6 may also be included.

The undervoltage protection module 4 is configured to delay the start of the control module 1 and the drive module 2 after a second preset time period when the audio power amplifier circuit 11 is powered on; the undervoltage protection module 4 is further configured to maintain a working state of the driving module 2 for a third preset time after the audio power amplifier circuit 11 is powered off; the second preset duration and the third preset duration are set based on a noise triggering critical interval of the speaker 10. The noise triggering threshold interval of the loudspeaker 10 may be determined according to theoretical calculations or experimentally. The second preset time period and the third preset time period may be equal to the noise triggering critical interval of the speaker 10, or may be obtained by performing safety conversion (for example, multiplying by a safety factor) on the basis of the noise triggering critical interval of the speaker 10. The noise triggering threshold interval of the loudspeaker 10 may be a specific value or may be a function of changes in external environmental and internal electrical parameters.

In an embodiment, the under-voltage protection module 4 includes an under-voltage protection capacitor. When the undervoltage protection module 4 is powered on, when detecting that the VCC voltage rises from the low voltage to exceed VTH2, the undervoltage protection capacitor is discharged first, and then the undervoltage protection capacitor is charged by using a preset micro-current (also called as undervoltage protection charging current), so that when the input voltage is higher than an undervoltage protection point (the point is defined as VT, wherein VTH2> VT), a period of time is delayed, and the driving module 2 is ensured to normally work when all modules are normal; and during the outage, VCC voltage falls to below VT fast, because the existence of undervoltage protection electric capacity, the cooperation control module 1 can ensure drive module 2 can last work certain time, realizes right speaker 10 discharges, does not have "puff' noise when ensureing to cut off the power supply.

The over-temperature protection module 5 is configured to select one of the following strategies according to the temperature of the audio power amplifier circuit 11: starting the driving module 2; without interfering with the operation of the drive module 2; reducing the output power of the driving module 2; and closing the drive module 2.

In an embodiment, the over-temperature protection module 5 is internally provided with a second-order over-temperature protection function, and is configured to detect that the audio power amplifier circuit 11 performs different reactions (including output power reduction and direct shutdown) at different operating temperatures, and the operating modes thereof are: when the temperature is lower than T1, the operation of the driving module 2 is not interfered. When the temperature reaches T1 but not T2, the over-temperature protection module 5 outputs a signal to the driving module 2, reduces the current capacity of the driving signal output by the driving module 2, and reduces the current peak values of the upper power tube and the lower power tube, thereby reducing the output power and reducing the circuit temperature; the advantage of this mode is that the chip can not cause the chip to trigger the overheat protection because of the continuous rise of temperature, and the customer experience is influenced. When the temperature reaches T2, the driving module 2 is immediately turned off to ensure the safety of the components of the audio power amplifier circuit 11. When the temperature is reduced to T3, the circuit recovers to normal operation, and the driving module 2 is started. The values of T1, T2 and T3 can be set according to actual needs, wherein T2> T1> T3.

The overcurrent protection module 6 is configured to detect a peak current flowing through the upper power tube Q51 and the lower power tube Q52, and when the peak current exceeds a safety range, turn off the corresponding upper power tube Q51 or the corresponding lower power tube Q52 in a current period. In the next cycle, the upper power tube Q51 or the lower power tube Q52 is still normally opened.

The embodiment further provides an audio power amplifier chip 12, which includes the audio power amplifier circuit 11.

The audio power amplifier circuit 11 and the audio power amplifier chip 12 may be connected in a dual power supply mode or a single power supply mode, fig. 4 shows an external connection schematic diagram of dual power supply, and fig. 5 shows an external connection schematic diagram of single power supply.

The connection mode and function of the resistors R101, R103, R104 and the capacitors C101, C102, C103 in fig. 4 can be understood with reference to the content shown in fig. 4, and the reference numbers of the ports of the audio power amplifier circuit 11 or the audio power amplifier chip 12 are consistent with the content in fig. 2.

Resistors R201, R202, R203, R204, R205, R206, R207 in fig. 5; the connection manner and function of the capacitors C201, C202, C203, C204, C205, C206, C207, C208, and C209 and the transistor Q201 can be understood with reference to the contents shown in fig. 5, and the reference numbers of the ports of the audio power amplifier circuit 11 or the audio power amplifier chip 12 are consistent with the contents in fig. 2.

When the audio power amplifier circuit 11 or the audio power amplifier chip 12 is compatible with two connection methods, or is used for supplying power through a single power supply, the audio power amplifier circuit 11 further includes a bias voltage setting module 7, and the bias voltage setting module 7 is arranged between the audio signal amplifier OP1 and the driving module 2. In an embodiment, the audio power amplifier circuit 11 is powered by a single power supply, and the bias voltage is set to VCC/2.

In summary, the present embodiment provides a mute control method, an audio power amplifier circuit, and an audio power amplifier chip. The mute control method comprises the following steps: receiving a mute setting signal; measuring an instantaneous current of a speaker directly or indirectly while receiving the mute setting signal; judging a discharging loop corresponding to the residual charge of the loudspeaker based on the instantaneous current; the discharge circuit includes: a positive discharge loop and a negative discharge loop; within a first preset time, conducting the corresponding discharge loop and driving the loudspeaker to discharge at a preset current, wherein the preset current is smaller than the normal working current of the loudspeaker; and after the first preset time period, outputting a control signal to drive the difference value between the current of the loudspeaker and the mute current to be within a preset range. Corresponding control modules are arranged in the audio power amplifier circuit and the audio power amplifier chip so as to realize the mute control method. By the configuration, residual charges in the loudspeaker are eliminated by discharging, noise is ensured not to be generated at the moment of mute switching, and the judgment of the discharging loop is carried out by instantaneous current, so that extra control risks of incapability of discharging or short circuit of an internal circuit and the like are avoided, and the problems in the prior art are solved.

The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art according to the above disclosure are within the scope of the present invention.

Claims

1. A mute control method is characterized by comprising the following steps:

receiving a mute setting signal;

measuring an instantaneous current of a speaker directly or indirectly while receiving the mute setting signal;

judging a discharging loop corresponding to residual charge of the loudspeaker based on the characteristics of the instantaneous current in the positive direction and the negative direction; the discharge circuit includes: the device comprises a positive discharging loop and a negative discharging loop, wherein the positive discharging loop and the negative discharging loop are independent from each other;

within a first preset time, conducting the corresponding discharge loop and driving the residual charge of the loudspeaker to discharge with a preset current, wherein the preset current is smaller than the normal working current of the loudspeaker; and the number of the first and second groups,

and after the first preset time, outputting a control signal to drive the difference value of the current of the loudspeaker and the mute current to be within a preset range so as to realize subsequent mute function until the mute setting signal disappears.

2. An audio power amplifier circuit, characterized in that the audio power amplifier circuit comprises a control module, and the control module is used for executing the mute control method according to claim 1.

3. The audio power amplifier circuit of claim 2, further comprising an audio signal amplifier, a driving module, an upper power transistor and a lower power transistor, wherein,

the audio signal amplifier comprises an audio signal positive phase end and an audio signal negative phase end, and is used for outputting a signal based on the pressure difference between the audio signal positive phase end and the audio signal negative phase end;

the input end of the driving module is connected with the output end of the audio signal amplifier, and the driving module is used for controlling the upper power tube and the lower power tube to work based on the received signals;

the anode of the upper power tube is used for being connected with the anode of an external power supply, the cathode of the upper power tube is connected with the anode of the lower power tube, and the cathode of the lower power tube is used for being connected with the cathode of the external power supply;

the negative electrode of the upper power tube is used for providing working current of the loudspeaker;

the upper power tube is used for forming the positive discharge loop, and the lower power tube is used for forming the negative discharge loop.

4. The audio power amplifier circuit according to claim 3, wherein the audio power amplifier circuit further comprises a mute function locking module, the control module comprises a first port, and an output end of the mute function locking module is connected with the first port;

when the mute function locking module does not output the mute setting signal, the mute function locking module outputs the mute setting signal only when the voltage of the input end of the mute function locking module is greater than a first preset voltage;

when the mute function locking module outputs the mute setting signal, the mute function locking module does not output the mute setting signal only when the voltage of the input end of the mute function locking module is smaller than a second preset voltage;

the first preset voltage is greater than the second preset voltage.

5. The audio power amplifier circuit of claim 3, wherein the control module comprises a second port for directly or indirectly measuring the instantaneous current of the speaker, the second port being connected to the negative electrode of the upper power tube.

6. The audio power amplifier circuit of claim 3, wherein the control module comprises a third port, and when receiving the mute setting signal, the third port is configured to output a first signal to the driving module, and when not receiving the mute setting signal, the third port is configured to output a second signal to the driving module;

7. The audio power amplifier circuit of claim 3, wherein the control module comprises a fourth port, the fourth port is connected to the output end of the audio signal amplifier, the fourth port is configured to intervene in the output signal of the audio signal amplifier after the first preset time period, so that the input signal of the driving module is clamped to a mute value, and when the signal received by the driving module is the mute value, the driving module controls a difference between the current of the speaker and the mute current to be within a preset range.

8. The audio amplifier circuit of claim 3, wherein the control module comprises a fifth port and a sixth port, the fifth port and the sixth port are respectively connected to one of the audio signal positive phase terminal and the audio signal negative phase terminal, and the fifth port and the sixth port are configured to intervene in the input signal of the audio signal amplifier to realize: and within a first preset time, conducting the corresponding discharge loop and driving the loudspeaker to discharge with preset current.

9. The audio power amplifier circuit according to claim 3, wherein the audio power amplifier circuit further comprises at least one of an under-voltage protection module, an over-temperature protection module and an over-current protection module;

the undervoltage protection module is used for delaying the control module and the driving module to start after a second preset time when the audio power amplifier circuit is powered on; the undervoltage protection module is also used for maintaining the working state of the driving module within a third preset time after the audio power amplifier circuit is powered off; the second preset time length and the third preset time length are set based on a noise triggering critical interval of the loudspeaker;

the over-temperature protection module is used for selecting one of the following strategies according to the temperature of the audio power amplifier circuit: starting the driving module; the operation of the driving module is not interfered; reducing the output power of the driving module; and, turning off the drive module;

the overcurrent protection module is used for detecting peak currents flowing through the upper power tube and the lower power tube, and when the peak currents exceed a safety range, the corresponding upper power tube or the corresponding lower power tube is closed in the current period.

10. An audio power amplifier chip, characterized in that, it comprises the audio power amplifier circuit of any one of claims 2 to 9.