A power management system for a rechargeable lithium battery-powered audio system

Abstract

The present invention relates to an audio power management system with a rechargeable lithium battery, which amplifies an audio signal through a power amplifier and plays it through a speaker. It has an external DC power supply, a charging IC, a boost selection circuit, a boost circuit, and a switch switching circuit. When the voltage of the lithium battery is lower than the minimum operating voltage of the audio system, the boost selection circuit boosts the voltage of the lithium battery; when the voltage of the lithium battery is higher than the minimum operating voltage of the audio system, the boost selection circuit directly outputs the voltage of the lithium battery. The boost circuit is connected to the charging IC and is used to boost the voltage of the lithium battery to the operating voltage of the power amplifier. The switch switching circuit is connected between the boost circuit and the power amplifier and is also connected to the DC power supply, and is used to switch different power supply paths to the power amplifier in different modes. The power supply system provided by the present invention can automatically switch the power supply between an external adapter and an internal battery to maintain the normal operation of the audio system.

Description

Technical Field

[0001] The present invention relates to an audio power management system, and more particularly to a rechargeable lithium battery audio power management system that can freely switch between an external DC power supply and an internal lithium battery when the lithium battery has a low voltage, so as to maintain the normal operation of the audio system. Background Art

[0002] Currently, most electronic devices, such as smartphones, tablets, and smart speakers, are powered by rechargeable lithium batteries. When the lithium battery has a low voltage, users usually directly connect it to an external power supply for charging, and at this time, a large instantaneous current will be generated, which has an adverse impact on the system. Moreover, when the lithium battery has a low voltage and the speaker needs to play music normally, due to the high power output of the power amplifier, the voltage difference of the lithium battery is extremely large, which also has a serious impact on the system power supply, causing the system to directly freeze and black out. The new generation of smart speakers currently work with an adapter. If the adapter is plugged into the external power supply for a long time and the audio device does not have a good power management circuit, the system will repeatedly charge and discharge for a long time, which also causes certain damage to the service life of the internal lithium battery. Summary of the Invention

[0003] To solve the above problems, an embodiment of the present invention provides a rechargeable lithium battery audio power management system that can automatically switch the power supply path between an external DC power supply and an internal lithium battery, thereby maintaining the normal operation of the audio system, increasing the service life of the lithium battery, and ensuring the sound quality of the music output by the speaker.

[0004] To solve the above problems, the embodiment of the present invention provides the following technical solutions:

[0005] An audio power management system with a rechargeable lithium battery is used to supply power to an audio system, so that an audio signal is amplified by a power amplifier and then played out through a speaker. It has an external DC power supply and a charging IC. When the lithium battery has a low voltage, the DC power supply charges it through the charging IC. It is characterized in that:

[0006] A boost selection circuit is connected to the charging IC. When the voltage of the lithium battery is lower than the minimum operating voltage of the audio system, the boost selection circuit boosts the voltage of the lithium battery to the minimum operating voltage of the audio system; when the voltage of the lithium battery is higher than the minimum operating voltage of the audio system, the boost selection circuit directly outputs the voltage of the lithium battery;

[0007] A boost circuit is connected to the charging IC and is used to boost the voltage of the lithium battery to the operating voltage of the power amplifier;

[0008] A switch switching circuit is connected between the boost circuit and the power amplifier and is also connected to the DC power supply, and is used to switch different power supply paths to the power amplifier under different power supply modes.

[0009] Further, the boost selection circuit includes:

[0010] A boost selection chip, whose input terminal is connected to the charging IC and serves as the input terminal of the boost selection circuit for receiving the output voltage of the lithium battery, and whose output terminal serves as the output terminal of the boost selection circuit for outputting a stable power supply voltage to the audio system; and

[0011] A first boost inductor is connected across the input terminal of the boost selection circuit and the boost selection chip, and together with the boost selection chip, boosts the lithium battery voltage to the minimum operating voltage of the audio system.

[0012] Further, the boost selection circuit includes:

[0013] Two first voltage-dividing resistors are connected in series between the input terminal of the boost selection circuit and the ground for voltage division;

[0014] Two input filter capacitors are connected in parallel between the input terminal of the boost selection circuit and the ground for filtering the signal at the input terminal of the boost selection circuit; and

[0015] Three output filter capacitors are connected in parallel between the output terminal of the boost selection circuit and the ground for filtering the signal at the output terminal of the boost selection circuit.

[0016] Further, the boost circuit includes:

[0017] A boost chip, whose input terminal is connected to the charging IC and serves as the input terminal of the boost circuit for receiving the output voltage of the lithium battery, and whose output terminal is connected to the power amplifier and serves as the output terminal of the boost circuit for outputting a stable operating voltage of the power amplifier;

[0018] A second boost inductor is connected in series to the input terminal of the boost circuit, and together with the boost chip, boosts the lithium battery voltage to the operating voltage of the power amplifier;

[0019] Two second voltage-dividing resistors are connected in series between the output terminal of the boost circuit and the ground, and the common node of the two is connected to the feedback pin of the boost chip for feeding back the output voltage of the boost circuit.

[0020] Further, the boost circuit further includes:

[0021] The bootstrap boost capacitor is connected between the input pin of the boost chip and the bootstrap boost pin;

[0022] The anti-radiation circuit is connected between the input pin of the boost chip and the ground, and is used to absorb high-frequency harmonics in the boost circuit, and includes a resistor and a capacitor connected in series with each other.

[0023] Further, the switch switching circuit includes:

[0024] The first MOS transistor, whose drain is connected to the DC power supply, is used to receive an external DC power supply signal, and whose source is used as the output terminal of the switch switching circuit and is connected to the power amplifier;

[0025] The second MOS transistor, whose gate is connected to the drain of the first MOS transistor, whose drain is connected to the boost circuit, and whose source is connected to the source of the first MOS transistor.

[0026] Further, both the first MOS transistor and the second MOS transistor are P-type MOS transistors.

[0027] Further, the switch switching circuit further includes:

[0028] Two third voltage-dividing resistors are connected in series between the drain of the first MOS transistor and the ground; and

[0029] A triode, whose base is connected to the common node of the two second voltage-dividing resistors, whose emitter is grounded, and whose collector is connected to the gate of the first MOS transistor.

[0030] Further, the triode is an NPN-type triode.

[0031] The power management system provided by the present invention has two modes of external DC power supply and internal lithium battery power supply. When the audio system is powered by an external DC power supply, on the one hand, the DC power supply charges the lithium battery through the charging IC, and on the other hand, provides a stable DC voltage to the power amplifier through the switch switching circuit; when the audio system is powered by an internal lithium battery, the switch switching circuit selects the voltage output by the boost circuit as the input voltage and provides it to the power amplifier. It not only ensures a stable power supply for the audio system when the lithium battery has low power, but also can provide a stable DC voltage to the power amplifier whether there is an external DC power supply or not, ensuring the sound quality of the music output by the audio. Description of the Drawings

[0032] To more clearly illustrate the solutions in the present invention or the prior art, the following will give a brief introduction to the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0033] Figure 1 It is a module diagram of a power management system for a rechargeable lithium battery audio in an embodiment of the present invention;

[0034] Figure 2 In an embodiment of the present invention Figure 1 The specific circuit diagram of the boost selection circuit in;

[0035] Figure 3 In an embodiment of the present invention Figure 1 The specific circuit diagram of the boost circuit in; and

[0036] Figure 4 In an embodiment of the present invention Figure 1 The specific circuit diagram of the switch switching circuit in. Specific embodiments

[0037] In order to enable those in the technical field to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs. The terms used in the description of the present invention in this specification are only for the purpose of describing specific embodiments, and are not intended to limit the present invention.

[0038] Referring to "embodiment" herein means that a specific feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present invention. The phrase appears at various positions in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0039] The embodiment of the present invention provides a module diagram of a power management system for a rechargeable lithium battery audio, as Figure 1As shown, it is used to supply power to the audio system so that the audio signal is amplified by the power amplifier 6 and then played through the speaker 7. It includes a lithium battery 1, a charging IC (integrated circuit) 2, a boost selection circuit 3, a boost circuit 4, a switch switching circuit 5, a power amplifier 6, a speaker 7, and a DC power supply 8. The lithium battery 1 is connected to the DC power supply 8 through the charging IC 2. When the lithium battery 1 has a low voltage, the DC power supply 8 can charge the lithium battery 1 through the charging IC 2. In this embodiment, the DC power supply 8 is a 12V DC voltage. The boost selection circuit 3 is connected to the charging IC 2, and the voltage signal output from the lithium battery 1 to the boost selection circuit 3 through the charging IC 2 is marked as VSYS. When the voltage VSYS is lower than the minimum operating voltage of the audio system, the boost selection circuit 3 boosts the voltage VSYS to the minimum operating voltage of the audio system and outputs it to the audio system; when the voltage VSYS output from the lithium battery 1 to the boost selection circuit 3 is higher than the minimum operating voltage of the system, the boost selection circuit 3 directly outputs this voltage to the audio system without any processing. In this embodiment, the audio system is an Android system, the voltage of its lithium battery 1 is 4.2V - 4.4V, and its minimum operating voltage is 3.85V. When the voltage VSYS output from the lithium battery 1 is lower than 3.85V, for example, 3.5V, the boost selection circuit 3 boosts the 3.5V voltage VSYS to 3.85V; when the voltage VSYS output from the lithium battery 1 is higher than 3.85V, for example: the lithium battery 1 is fully charged at 4.2V, the boost selection circuit 3 directly outputs the 4.2V VSYS voltage and uses it as the working power supply for the entire audio system.

[0040] The boost circuit 4 is connected to the charging IC 2 and is used to boost the voltage VSYS output from the lithium battery 1 to the working voltage of the power amplifier 6, that is, 12V. The switch switching circuit 5 is connected between the boost circuit 4 and the power amplifier 6 and is also connected to the DC power supply 8, and is used to switch different power supply paths to the power amplifier 6 in different power supply modes. Specifically, when the audio system is powered by the external DC power supply 8, the DC power supply 8 not only charges the lithium battery 1 through the charging IC 2, but also the switch switching circuit 5 selects to supply power to the power amplifier 6 from the DC power supply 8. At this time, the boost circuit 4 and the switch switching circuit 5 are in a disconnected state; when the audio system cuts off the external DC power supply 8 and uses the built-in lithium battery 1 for power supply, since the working voltage required by the power amplifier 6 is 12V, the boost circuit 4 boosts the voltage VSYS and outputs it to the power amplifier 6 through the switch switching circuit 5. At this time, the boost circuit 4 and the switch switching circuit 5 are in a connected state.

[0041] The audio system in this embodiment is powered by dual power supplies, namely, an internal lithium battery 1 and an external DC power supply 8. When the voltage of the lithium battery 1 is low, the DC power supply 8 charges it through a charging IC2, and a boost selection circuit 3 determines whether to boost the voltage value of VSYS by judging whether the voltage VSYS is lower than the minimum operating voltage of the audio system. Meanwhile, a switch switching circuit 5 can select different power supply paths for a power amplifier 6 according to the power supply mode of the entire audio system, that is, whether there is an external DC power supply 8.

[0042] In summary, when the lithium battery 1 in the power management system of the present invention has a low voltage and high-power music needs to be played, when outputting a power of 10W, the instantaneous discharge current of the lithium battery 1 is as high as 3 - 5A, generating a voltage drop of about 0.5V. However, the voltage VSYS is boosted and stabilized by the boost selection circuit 3 to ensure a stable voltage output of 3.85V, maintaining the stability of the power supply of the entire audio system. Meanwhile, when the lithium battery 1 is fully charged, the boost selection circuit 3 is in a direct-through mode, directly outputting the voltage of the lithium battery 1 to the audio system, improving the conversion efficiency and avoiding the problem of abnormal duty ratio of high-voltage to low-voltage conversion. All in all, the power supply system of the present invention can not only enable the audio system to have a stable power input, ensuring the quality of music, but also extend the service life of the lithium battery 1.

[0043] Figure 2 As shown in the embodiment of the present invention Figure 1Specific circuit diagram of the boost selection circuit 3, which includes a boost selection chip U1, a first boost inductor L1, two first voltage dividing resistors R1, R2, two input filter capacitors C1, C2, a capacitor C3, and three output filter capacitors C4, C5, C6. The boost selection chip U1 has multiple pins. Its pins 1, 2, 3, and 4 are output terminals, which are connected together and simultaneously serve as the output terminals of the boost selection circuit 3, outputting a stable 3.85V power supply to the audio system. Pins 5, 6, 7, and 8 are grounded. Pins 13, 14, and 15 are input terminals, which are connected together and serve as the input terminals of the boost selection circuit 3 and are connected to the charging IC2 for receiving the voltage VSYS output by the lithium battery 1. Pins 9, 10, 11, and 12 are connected. The first boost inductor L1 is connected across the input terminal of the boost selection circuit 3 and the boost selection chip U1. Specifically, the first boost inductor L1 is connected across pins 13, 14, 15 and pins 9, 10, 11, 12 of the boost selection chip U1. In this embodiment, the first boost inductor L1 and the boost selection chip U1 together boost the voltage VSYS to 3.85V. The input filter capacitors C1 and C2 are connected in parallel between the input terminal of the boost selection circuit 3 and the ground for filtering the input terminal signal of the boost selection circuit 3. The two first voltage dividing resistors R1 and R2 are connected in series between the input terminal of the boost selection circuit 3 and the ground for voltage division. The capacitor C3 is connected between the common node of the first voltage dividing resistors R1 and R2 and the ground, and pin 16 of the boost selection chip U1 is connected to the common node of the resistors R1 and R2. The three output filter capacitors C4, C5, and C6 are connected in parallel between the output terminal of the boost selection circuit 3 and the ground for filtering the output terminal signal of the boost selection circuit 3.

[0044] Figure 3 As shown in the embodiment of the present invention Figure 1Specific circuit diagram of the boost circuit 4, which includes a boost chip U2, a second boost inductor L2, multiple resistors R3, R4, R5, R6, R7, two second voltage-dividing resistors R8, R9, and multiple capacitors C7, C8, ..., C18. The boost chip U2 has multiple pins. Pins 4, 5, 6, and 7 are input pins, which are connected to each other and serve as the input end of the boost circuit 4 to be connected to the charging IC2 to receive the voltage VSYS. In this embodiment, the second boost inductor L2 is connected in series at the input end of the boost circuit 4 and, together with the boost chip U2, boosts the voltage VSYS to 12V. Capacitors C7 and C8 are connected in parallel between the input end of the boost circuit 4 and the ground for filtering. Capacitor C9 is connected across the input pin and the bootstrap boost pin of the boost chip U2, that is, between pin 4 and pin 8, and serves as a bootstrap boost capacitor. Resistor R3 and capacitor C18 form a radiation protection circuit and are connected in series between the input pin of the boost chip U2 and the ground, that is, between pin 4 and the ground, for absorbing high-frequency harmonics in the boost circuit 4. Since the boost circuit 4 generates high-frequency harmonics that are harmful to the human body during operation, the high-frequency harmonics are absorbed after passing through this radiation protection circuit, making it safer and more reliable for users to use. Resistor R4 is connected between pin 7 and pin 3 of the boost chip U2 for adjusting the frequency of the system PFM (Pulse Frequency Modulation) wave.

[0045] Pin 2 of the boost chip U2 receives the audio system enable signal and is grounded via capacitor C10. In this embodiment, the enable signal is triggered by the switch button of the audio system. Capacitor C11 is connected between pin 1 and the ground, and resistor R5 is connected between pin 3 and the ground. The two form the reference source of the entire circuit. Pins 14, 15, and 16 are connected to serve as the output end of the boost circuit 4 and are connected to the switch switching circuit 5 to output a stable 12V DC power supply. Capacitors C12, C13, and C14 are connected in parallel between the output end of the boost circuit 4 and the ground for filtering. The two second voltage-dividing resistors R8 and R9 are connected in series between the output end of the boost circuit 4 and the ground, and their common node is connected to pin 17 of the boost chip U2 to provide the output voltage feedback signal of the voltage-dividing circuit 4. In this embodiment, pin 17 serves as the feedback pin of the boost chip U2, and the received voltage feedback signal needs to be stabilized at 1.2V. If the feedback voltage signal is greater than or less than 1.2V, the boost chip U2 can make timely adjustments internally to ensure that the voltage feedback signal received by pin 17 is 1.2V, thereby ensuring the stability of the 12V DC voltage output by the boost circuit 4. Pin 18 of the boost chip U2 serves as a comparison terminal. Resistor R6 and capacitor C15 are connected in series and then in parallel with capacitor C16, and are connected between pin 18 and the ground. Pin 19 is grounded through resistor R7, and pin 10 is grounded through capacitor C17. The two work together to adjust the maximum input current of the entire circuit. In this embodiment, the maximum input current is 11.3A.

[0046] Figure 4 In the embodiments of the present invention Figure 1Specific circuit diagram of the middle switch switching circuit 5, which includes a first MOS (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET, metal-oxide-semiconductor field-effect transistor) tube Q1, a second MOS tube Q2, a triode Q3, two third voltage-dividing resistors R10, R11, a resistor R12, and multiple capacitors C18, C19, C20, C21. In this embodiment, both the first MOS tube Q1 and the second MOS tube Q2 are P-type MOS tubes, and the triode Q3 is an NPN triode. In other embodiments, other switching elements can be used to achieve the switch switching function, and it is not limited thereto. Among them, the drain of the first MOS tube Q1 is connected to the DC power supply 8 for receiving a 12V DC voltage, the gate is connected to the source through the resistor R12, and the source is used as the output terminal of the switch switching circuit 5 and is connected to the power amplifier 6. The gate of the second MOS tube Q2 is connected to the DC power supply 8 to receive a 12V DC voltage, the drain is connected to the drain of the first MOS tube Q1, and the source is connected to the boost circuit 4 to receive the 12V DC voltage output by the boost circuit 4. The third voltage-dividing resistors R10 and R11 are connected in series between the drain of the first MOS tube Q1 and the ground, and their common node is connected to the base of the triode Q3. The collector of the triode Q3 is connected to the gate of the first MOS tube Q1, and its emitter is grounded. The capacitors C18 and C19 are connected in parallel between the output terminal of the switch switching circuit 5 and the ground, and the capacitors C20 and C21 are connected in parallel between the drain of the second MOS tube Q2 and the ground. Among them, the capacitors C18, C19, C20, and C21 are all filter capacitors. In this embodiment, when the audio system is powered by an external DC power supply 8, when the drain of the first MOS tube Q1 and the gate of the second MOS tube Q2 receive the 12V voltage signal output by the DC power supply 8, the external 12V voltage directly acts on the gate of the second MOS tube, and at the same time its source also receives the 12V voltage signal output by the boost circuit 4, so that the voltage difference between the gate and the source of the second MOS tube Q2 is 0, and there is a certain voltage difference between the gate and the source of the first MOS tube, so that the second MOS tube Q2 is cut off, the first MOS tube Q1 and the triode Q3 are turned on, and the DC power supply 8 directly supplies power to the power amplifier 6 through the first MOS tube Q1. On the contrary, when the audio system disconnects the external DC power supply 8 and is powered by the built-in lithium battery 1, when the drain of the first MOS tube Q1 and the gate of the second MOS tube Q2 do not receive the 12V voltage signal output by the DC power supply 8, the second MOS tube Q2 is turned on, the first MOS tube Q1 and the triode Q3 are cut off, and the boost circuit 4 supplies power to the power amplifier 6 through the second MOS tube Q2. Therefore, when the entire system has or does not have an external DC power supply 8, and regardless of whether the lithium battery 1 is low on power, the power amplifier 6 can ensure a stable 12V DC voltage input, thus ensuring the quality of the audio playing music.In this embodiment, the entire power supply switching operation is completed by a pure hardware circuit, with a rapid response.

[0047] In summary, for the audio power management system with a rechargeable lithium battery provided in this embodiment, when the entire system is powered by an external DC power supply 8, the DC power supply 8 not only charges the lithium battery 1 through the charging IC2, so that the lithium battery 1 is always in a fully charged state (the voltage VSYS is greater than 3.85V), and thus the boost selection circuit 3 directly outputs the voltage VSYS to the audio system, but also the DC power supply 8 provides a 12V DC voltage to the power amplifier 6 through the switch switching circuit 5. When the system disconnects the DC power supply 8 and selects to be powered by the internal lithium battery 1, if the lithium battery 1 has a low voltage and the voltage VSYS is less than 3.85V, the boost selection circuit 3 boosts the voltage VSYS so that the boosted voltage is stabilized at 3.85V and output to the audio system. If the voltage VSYS provided by the lithium battery 1 is greater than 3.85V, the boost selection chip U1 in the boost selection circuit 3 is in a switched state, and the switch is directly connected to output this voltage to the audio system. At the same time, the voltage VSYS is boosted to 12V through the boost circuit 4 and output to the switch switching circuit 5. The switch switching circuit 5 selects the 12V voltage output by the boost circuit 4 as the input voltage and provides it to the power amplifier 6.

[0048] In summary, the audio power supply system provided by the present invention can not only enable the audio system to have a stable power input, ensuring the quality of music, but also extend the service life of the lithium battery 1.

[0049] Obviously, the embodiments described above are only a part of the embodiments of the present invention, rather than all of them. The accompanying drawings show preferred embodiments of the present invention, but do not limit the patent scope of the present invention. The present invention can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosed content of the present invention more thorough and comprehensive. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing specific embodiments, or perform equivalent replacements for some of the technical features. Any equivalent structure made by using the specification and drawings of the present invention, directly or indirectly applied to other related technical fields, shall be equally within the scope of the patent protection of the present invention.

Claims

1. An audio power management system with a rechargeable lithium battery is used to supply power to an audio system, enabling an audio signal to be amplified by a power amplifier and then played through a speaker. It has an external DC power supply and a charging IC. When the lithium battery has a low voltage, the DC power supply charges it through the charging IC. Its characteristics are as follows: A boost selection circuit is connected to the charging IC. When the voltage of the lithium battery is lower than the minimum operating voltage of the audio system, the boost selection circuit boosts the voltage of the lithium battery to the minimum operating voltage of the audio system; when the voltage of the lithium battery is higher than the minimum operating voltage of the audio system, the boost selection circuit directly outputs the voltage of the lithium battery. A boost circuit is connected to the charging IC and is used to boost the voltage of the lithium battery to the operating voltage of the power amplifier. A switch switching circuit is connected between the boost circuit and the power amplifier and is also connected to the DC power supply, and is used to switch different power paths to supply power to the power amplifier under different power supply modes. Among them, the working principles of the boost circuit and the switch switching circuit are as follows: When the audio system is externally powered by the DC power supply, the DC power supply charges the lithium battery through the charging IC. At the same time, the switch switching circuit selects to supply power to the power amplifier by the DC power supply. At this time, the boost circuit and the switch switching circuit are in a disconnected state. When the audio system cuts off the external DC power supply and uses the built-in lithium battery to supply power, the voltage output by the lithium battery through the charging IC2 is boosted by the boost circuit and output to the power amplifier through the switch switching circuit. At this time, the boost circuit and the switch switching circuit are in a connected state.

2. The audio power management system with a rechargeable lithium battery as claimed in claim 1, wherein The boost selection circuit includes: A boost selection chip, whose input terminal is connected to the charging IC and serves as the input terminal of the boost selection circuit to receive the output voltage of the lithium battery, and whose output terminal serves as the output terminal of the boost selection circuit to output a stable power supply voltage to the audio system; and A first boost inductor is connected across the input terminal and the boost selection chip of the boost selection circuit, and together with the boost selection chip boosts the voltage of the lithium battery to the minimum operating voltage of the audio system.

3. The audio power management system with a rechargeable lithium battery as claimed in claim 1, wherein, The boost selection circuit includes: Two first voltage-dividing resistors are connected in series between the input terminal of the boost selection circuit and the ground for voltage division. Two input filter capacitors are connected in parallel between the input terminal of the boost selection circuit and the ground to filter the signal at the input terminal of the boost selection circuit; and Three output filter capacitors are connected in parallel between the output terminal of the boost selection circuit and the ground to filter the signal at the output terminal of the boost selection circuit.

4. The audio power management system with a rechargeable lithium battery as described in claim 1, characterized in that, The boost circuit includes: A boost chip, whose input terminal is connected to the charging IC and serves as the input terminal of the boost circuit to receive the output voltage of the lithium battery, and whose output terminal is connected to the power amplifier and serves as the output terminal of the boost circuit to output a stable operating voltage of the power amplifier. A second boost inductor, connected in series to the input end of the boost circuit, and together with the boost chip, boosts the lithium battery voltage to the operating voltage of the power amplifier; Two second voltage-dividing resistors, connected in series between the output end of the boost circuit and the ground, and the common node of the two is connected to the feedback pin of the boost chip, for feeding back the output voltage of the boost circuit.

5. The audio power management system with a rechargeable lithium battery as claimed in claim 4, wherein The boost circuit further includes: A bootstrap boost capacitor, connected between the input pin and the bootstrap boost pin of the boost chip; A radiation protection circuit, connected between the input pin of the boost chip and the ground, for absorbing high-frequency harmonics in the boost circuit, which includes a resistor and a capacitor connected in series.

6. The audio power management system with a rechargeable lithium battery as described in claim 1, characterized in that, The switch switching circuit includes: A first MOS transistor, whose drain is connected to the DC power supply, for receiving an external DC power supply signal, and whose source serves as the output end of the switch switching circuit and is connected to the power amplifier; A second MOS transistor, whose gate is connected to the drain of the first MOS transistor, whose drain is connected to the boost circuit, and whose source is connected to the source of the first MOS transistor.

7. The audio power management system with a rechargeable lithium battery as described in claim 6, characterized in that, Both the first MOS transistor and the second MOS transistor are P-type MOS transistors.

8. The audio power management system with a rechargeable lithium battery as claimed in claim 6, wherein The switch switching circuit further includes: Two third voltage-dividing resistors, connected in series between the drain of the first MOS transistor and the ground; and A triode, whose base is connected to the common node of the two second voltage-dividing resistors, whose emitter is grounded, and whose collector is connected to the gate of the first MOS transistor.

9. The audio power management system with a rechargeable lithium battery as claimed in claim 8, wherein The triode is an NPN-type triode.

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