CN111212363A

CN111212363A - Circuit for switching TPA3255 series power amplifier IC multifunctional output

Info

Publication number: CN111212363A
Application number: CN202010146314.8A
Authority: CN
Inventors: 张太武
Original assignee: Iag Group Co ltd
Current assignee: Iag Group Co ltd
Priority date: 2020-03-04
Filing date: 2020-03-04
Publication date: 2020-05-29

Abstract

The invention provides a circuit for switching TPA3255 series power amplifier IC multifunctional output, belonging to the field of sound box circuits. The invention comprises a pre-processing circuit and a power amplifying circuit, wherein the output end of the power amplifying circuit is connected with a loudspeaker, the pre-processing circuit comprises a signal input module connected with an input signal, a DRC control module connected with the output end of the signal input module, a first pre-frequency dividing module and a second pre-frequency dividing module which are respectively connected with the output end of the DRC control module, an audio signal switch, and a multifunctional output condition setting module connected with the input ends of an MI pin and an M2 pin of the power amplifier IC, wherein the power amplifying circuit comprises an output processing module, a power amplifier IC connected with the output end of the output processing module. The invention can be compatible with TPA3255 series power amplifier IC.

Description

Circuit for switching TPA3255 series power amplifier IC multifunctional output

Technical Field

The invention relates to a sound box circuit, in particular to a circuit for switching TPA3255 series power amplifier IC multifunctional output.

Background

The American TI TPA3245 CLASS D series power amplifier IC comprises models of TPA3245/TPA3251/TPA3255 and the like, when sound or audio circuit design is carried out, the same corresponding circuit development design can be carried out according to different power amplifier IC product requirements, if the same series of models can also consider using the same sound circuit, but if the same series of models can use different audio circuits and power amplifiers, thus, various costs such as research and development cost, purchase cost, production cost and the like of a company are greatly increased. If the invention reasonably converts the audio power amplifier control mode through some audio power amplifier circuits, and achieves the multifunctional conversion input and output mode through the electronic frequency division technology, the analog DRC control technology and the mode control technology, the invention idea of controlling the cost rise is achieved.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a circuit for switching the multifunctional output of a TPA3255 series power amplifier IC.

The invention comprises a pre-processing circuit and a power amplifying circuit, wherein the output end of the power amplifying circuit is connected with a loudspeaker, the pre-processing circuit comprises a signal input module connected with an input signal, a DRC control module connected with the output end of the signal input module, a first pre-frequency dividing module and a second pre-frequency dividing module which are respectively connected with the output end of the DRC control module, and an audio signal switch, the selection end of the audio signal switch is respectively connected with the output end of the first pre-frequency dividing module and the output end of the second pre-frequency dividing module, and the normal connection end of the audio signal switch is connected with the input end of the power amplifying circuit;

the power amplification circuit comprises an output processing module, a power amplifier IC connected with the output end of the output processing module, and a multifunctional output condition setting module connected with the MI pin of the power amplifier IC and the input end of the M2 pin.

The invention is further improved, the first PRE-frequency division module is used for outputting the PRE AUDIO signal processed by the analog effect of the digital DSP, and the second PRE-frequency division module is used for outputting the FLAT AUDIO signal which is not processed and has the horizontal AUDIO signal of the passing frequency band.

The invention is further improved, the first prepositive frequency division module comprises three frequency division branches and frequency amplification units respectively connected with the output ends of the three frequency division branches, the three frequency division branches are respectively used for dividing input frequency signals into high-frequency, medium-frequency and low-frequency bands, each frequency division branch comprises more than one BY PASS circuit connected in series, and each BY PASS circuit comprises a two-order high-PASS circuit and a two-order low-PASS circuit connected in series.

The invention is further improved, the frequency amplification unit comprises a power amplifier U207, the power amplifier U207 is composed of a power amplifier unit U207A and a power amplifier unit U207B, wherein,

the positive phase input end of the power amplification unit U207A is grounded, the negative phase input end is respectively connected with the output ends of the low-frequency division branch and the intermediate-frequency division branch, or the output ends of the three frequency division branches, and is connected with the output end of the power amplification unit U207A through a capacitor C260 and a resistor R259 which are connected in parallel, the output end of the power amplification unit U207A outputs a low-and-medium-frequency PRE AUDIO amplification signal through the capacitor C259, the positive power pin of the power amplification unit U207A is respectively connected with a grounding capacitor C258 and a plus 15V power resistor R258, and the negative power pin of the power amplification unit U207A is respectively grounded through a capacitor C263 and connected with a-15;

the non-inverting input end of the power amplification unit U207B is grounded, the inverting input end is connected with the high-frequency division branch, and is connected with the output end of the power amplification unit U207B through a capacitor C265 and a resistor R263 which are connected in parallel, and the output end of the power amplification unit U207B outputs a high-frequency PRE AUDIO amplification signal through a capacitor C264.

The invention is further improved, wherein the second pre-frequency division module comprises a first frequency division branch and a second frequency division branch, wherein the first frequency division branch outputs a low-frequency FLAT AUDIO signal, and the second frequency division branch outputs a high-frequency FLAT AUDIO signal.

In a further development of the invention, the audio signal changeover switch comprises switches SW2-a and SW2-B, wherein,

two selection ends of the switch SW2-A are respectively connected with a middle and low frequency FLAT AUDIO signal output end and a middle and low frequency PRE AUDIO amplification signal output end, a normally connected end of the switch SW2-A outputs a middle and low frequency signal LPF & CH1,

two selection ends of the switch SW2-B are respectively connected with the high-frequency FLAT AUDIO signal output end and the high-frequency PREAUDIO AUDIO amplification signal output end, and the normally-connected end of the switch SW2-B outputs a high-frequency signal HPF & CH 2.

In a further improvement of the invention, a resistor R154 is further arranged at the normally connected end of the switch SW2-A and the normally connected end of the switch SW 2-B.

The invention is further improved, the output processing module converts the middle and low frequency signals and the high frequency signals output by the pre-processing circuit into six paths of signals, which are respectively connected with 4 input pins of the power amplifier chip U302, wherein,

the INPUT end of the first path of signal INPUT _ A is connected with the normally connected end of the switch SW2-B, and the output end of the first path of signal INPUT _ A is connected with a signal INPUT pin 5INPUT _ A pin of the power amplifier chip U302;

the INPUT end of the sixth signal INPUT _ a is connected with the normal end of the switch SW2-a, and the output end is connected with the signal INPUT pin 16INPUT _ C pin of the power amplifier chip U302;

the output processing module comprises a high-frequency signal processing unit and a middle-low frequency signal processing unit, wherein the high-frequency signal processing unit comprises an operational amplifier U301A, a pin 2 of the U301A is connected with a normally-connected end of a switch SW2-B through a resistor R301 and is connected with an output pin 1 of the operational amplifier U301A through a capacitor C303 and a resistor R303 which are connected in parallel, a pin 3 of the operational amplifier U301A is grounded, a pin 8 is connected with a positive electrode of a power supply, a pin 4 is connected with a negative electrode of the power supply, the output pin 1 outputs a second path signal INPUT _ BB through a capacitor C381, a third path signal INPUT _ B is output through the capacitor C301, and output ends of the second path signal INPUT _ BB and the third path signal INPUT _ B are respectively connected with a signal INPUT pin 6INPUT _ B pin of;

the middle and low frequency signal processing unit comprises an operational amplifier U301B, wherein a pin 5 of the U301B is grounded, a pin 6 is connected with a normally connected end of a switch SW2-A through a resistor R302 and is connected with an output pin 7 of the operational amplifier U301B through a capacitor C304 and a resistor R304 which are connected in parallel, the output pin 7 outputs a fourth signal INPUT _ D through the capacitor C302 and outputs a fourth signal INPUT _ DD through a capacitor C382, and output ends of the fourth signal INPUT _ D and the fifth signal INPUT _ DD are respectively connected with a signal INPUT pin 17INPUT _ D pin of a power amplifier chip U302.

The multifunctional output condition setting module is further improved and comprises resistors R376-R379, wherein one ends of the resistor R376 and the resistor R377 are respectively connected with a pin 3M1 of the power amplifier chip U302, one ends of the resistor R378 and the resistor R379 are respectively connected with a pin 4M2 of the power amplifier chip U302, the other ends of the resistor R376 and the resistor R378 are grounded, and the other ends of the resistor R377 and the resistor R379 are respectively connected with a pin 11DVDD of the power amplifier chip U302.

The invention is further improved, the multifunctional output condition setting module further comprises a resistor R360 and a resistor R351, wherein one end of the resistor R360 is connected to the signal INPUT pin 16INPUT _ C pin of the power amplifier chip U302, one end of the resistor R351 is connected to the signal INPUT pin 17INPUT _ D pin of the power amplifier chip U302, and the other ends of the resistor R360 and the resistor R351 are respectively grounded.

Compared with the prior art, the invention has the beneficial effects that: the same circuit is compatible with TPA3255 series power amplifier ICs, only the power supply voltage needs to be adjusted, and the power amplifier chips are TPA3245, TPA3251 and TPA3255X series CLASS D series power amplifier ICs which can be directly replaced, so that the research and development cost and the production cost of a company are greatly reduced.

Drawings

FIG. 1 is a block diagram of the present invention;

FIG. 2 is a schematic diagram of a pre-processing circuit according to an embodiment of the present invention;

FIG. 3 is a schematic circuit diagram of a first pre-divider module;

FIG. 4 is a schematic diagram of a second frequency-dividing module circuit and an audio signal switch circuit;

FIG. 5 is a schematic diagram of a power amplifier circuit according to an embodiment of the invention;

FIG. 6 is a circuit schematic of an output processing module;

FIG. 7 is a partial enlarged view of a power amplifier chip IC;

FIG. 8 is a schematic diagram of a single-channel output circuit of a power amplifier chip IC;

FIG. 9 is a schematic diagram of two-channel output single-channel of a power amplifier chip IC;

FIG. 10 is a schematic diagram of a single channel output of a power amplifier chip IC 2.1 channel;

fig. 11 is a schematic diagram of a single output channel of an IC 4 power amplifier chip.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

As shown in fig. 1, the present invention includes a pre-processing circuit and a power amplifying circuit, an output terminal of the power amplifying circuit is connected to a speaker, wherein the pre-processing circuit includes a signal input module connected to an input signal, a DRC (dynamic range control) control module connected to an output terminal of the signal input module, a first pre-frequency dividing module and a second pre-frequency dividing module connected to an output terminal of the DRC control module, respectively, and an audio signal switch, a selection terminal of the audio signal switch is connected to an output terminal of the first pre-frequency dividing module and an output terminal of the second pre-frequency dividing module, respectively, and a normal terminal of the audio signal switch is connected to an input terminal of the power amplifying circuit;

The pre-processing circuit of the invention mainly has the function of pre-processing, can realize electronic frequency division, DRC control and the like, and can realize different input requirements and technical requirements through different parameter adjustment.

The power amplifying circuit mainly has the functions of power amplifying processing, input and output MODE control and the like are realized through MODE PIN M1& M2 high and low level control, and different input requirements and technical requirements can be realized through different parameter adjustment.

Under the condition of jumping from the traditional cognition, the circuit of the invention adopts the electronic frequency division technology, the analog DRC control technology and the mode control technology which are originally created by the applicant, and the same IC is developed to achieve a multifunctional output circuit. The applicant develops GZV4A/GZV4D/GZV4D/GZV8D and other network audio power amplifiers and other different types of active power amplifiers, such as: the circuit of the invention is used in various acoustic circuits such as CS08A, TYPON-AX 8-MBT, etc. The power amplifier chip used by the circuit of the invention can be directly replaced by CLASS D series power amplifier ICs of TPA3245, TPA3251 and TPA3255X series of American TI company, and only needs to adjust the supply voltage. The compatibility is strong, and the research and development cost and the production cost of a company are greatly reduced.

As shown in fig. 2 to 4, the first PRE-divide module of this example is used to output PRE AUDIO signals processed by digital DSP analog effect, and the second PRE-divide module is used to output FLAT AUDIO signals with horizontal pass band without processing. The invention uses the electronic frequency division technology to carry out preprocessing, thus achieving the multifunctional conversion of the preposed input function.

As shown in fig. 3, the first pre-frequency division module includes three frequency division branches and frequency amplification units respectively connected to output ends of the three frequency division branches, the three frequency division branches are respectively used for dividing an input frequency signal into high frequency, intermediate frequency and low frequency bands, the frequency division branch includes more than one BY PASS circuit connected in series, and the BY PASS circuit includes a two-step high-PASS circuit and a two-step low-PASS circuit connected in series.

The frequency amplification unit of the embodiment comprises a power amplifier U207, wherein the power amplifier U207 comprises a power amplifier unit U207A and a power amplifier unit U207B, wherein,

The circuit is invented on the basis of the traditional mature operational amplifier, and the multi-section analog electronic frequency division design obtains multiple functions of EQ control, Q value control, HI PASS, L0 PASS, BY PASS, DRC, ANC control, sound effect control and the like which are the same as digital DSP, thereby achieving the analog effect of the digital DSP. The Wharfe Pro engineer inspects the high-low frequency driver of the circuit and samples radiation characteristics at 36 different points, thereby eliminating space radiation such as EMI (electro-magnetic interference) generated by intrinsic high frequency of the digital DSP and meeting the national advocated green environmental protection policy. Meanwhile, due to the unique artistic measurement technical state of WharfedalePro, the designed brand new simulation DSP effect assembly ensures that the sound radiation coverage angle is matched with the high frequency, the frequency division point and the low frequency. The noise pollution of noise to human ears and space is effectively reduced by the analog ANC technology. The real audio signal achieves a reasonable coverage pattern of its sustained response consistency, so that the entire sound field area is reasonably covered with uniformity and high definition.

The following specific analysis was performed:

the U204A unit forms a dual-order high-pass circuit, and the specific low-frequency cutoff frequency F1 is 32.9Hz, that is, the attenuation of-12 db per frequency multiplication is performed on frequencies below 32.9 Hz. By changing the parameters of C241/C242/R241/R242, the cut-off frequency of F1 can be infinitely close to the 20Hz low-frequency audio frequency, and lower low-frequency extension can also be continued. Meanwhile, the U204B unit forms a two-stage low-pass circuit, and the transition frequency F2 is 129.24 Hz. I.e., attenuation of-12 db per octave for frequencies above 129.24 Hz. The high-pass frequency 129.24Hz can be extended upwards or downwards by changing the parameters of R244/R245/C244/C245. U204A and U204B form a BY BASS band pass circuit of 32.9 Hz-129.24 Hz. Meanwhile, the bandwidth of the band-on circuit can be adjusted correspondingly by adjusting the parameters of U204A and U204B. The unit circuit can only pass the bandwidth as follows: 32.9 Hz-129.24 Hz. The two-stage LO PASS & HI PASS form a BY PASS circuit, and meanwhile, the Q value formed BY the two-stage high-low PASS circuit is as follows: the slope of +/-12 db. If a BY PASS circuit of equal parameters is added after the operational amplifier U204, a Q value of: a slope of +/-24 db. Continued extension theoretically results in a slope Q of approximately 90 degrees. This all implements digital DSP related processing data. Wherein U204 processes low frequency data, U205 processes low intermediate frequency data, and U206 processes low high frequency data. The functions of the two audio frequency conversion modules are the same, but the audio frequency conversion modules process different audio frequencies, and the parameter adjustment of the two audio frequency conversion modules can realize frequency division function interchange and audio data interchange. Electronic frequency division is possible using the processed audio data. U204(LF) + U205(MF) ═ medium-low frequency, U206(HF) high frequency. U204/U205/U206 outputs an audio signal that is subject to full frequency processing by the analog DSP. The U206 output end C261/R260 and the U204/U205 output end can be utilized to form an adder through a U207A unit to output full-frequency audio signals to the power amplifier IC/TPA3245& TPA3251& TPA3255 input bridge single-channel power amplification output. The PRE AUDIO signal can also be processed through the output of the U207A unit and then output through another channel which is branched to SW2/B by R154. After the output of the operational amplifier U301 in the power amplifying circuit is processed, 2 channels, 2.1 channels and 4 channels can be formed and output to the power amplifier chip TPA32 series for power output.

As shown in fig. 3, the second pre-frequency dividing module of this embodiment includes a first frequency dividing branch and a second frequency dividing branch, where the first frequency dividing branch outputs a low-frequency FLAT AUDIO signal, and the second frequency dividing branch outputs a high-frequency FLAT AUDIO signal.

The audio signal switching switch of this example includes switches SW2-a and SW2-B, wherein,

Preferably, the normally connected end of the switch SW2-A and the normally connected end of the switch SW2-B are further provided with a resistor R154.

As shown in fig. 5 and fig. 6, the output processing module converts the low-medium frequency signal and the high-frequency signal output by the pre-processing circuit into six paths of signals, which are respectively connected to 4 input pins of the power amplifier chip U302, wherein,

The working principle of the output processing module is explained in detail as follows:

the INPUT _ A + the INPUT _ B & the INPUT _ C + the INPUT _ D form two paths of differential INPUTs to a power amplifier chip TPA32 for power amplification and two paths of output. If only INPUT _ A + INPUT _ B is connected, the single-channel audio signal can be output to a power amplifier chip and then bridged with a single-channel subwoofer or a single-channel full-frequency power audio signal is output. If INPUT _ AA + INPUT _ A + INPUT _ D + INPUT _ DD are accessed, a 4-lane power output may be formed. If only the differential INPUTs are formed as INPUT _ C + INPUT _ D, then the INPUTs INPUT _ A and INPUT _ AA will form a 2.1 channel power output. The basis is that the former electronic frequency division needs to perform corresponding bass and mid-high electronic frequency division processing, and the correlation analysis is not described herein again. Meanwhile, the low-medium frequency output of U204(LF) + U205(MF) can be used, a low-medium frequency adder is formed by a U207A unit, the low-medium frequency loudspeaker is connected with the power amplifier, the high-frequency output of U206(HF) is formed by a U207A unit, the high-frequency audio signal is connected with the power amplifier and the high-frequency loudspeaker, and the high-frequency audio signal is subjected to electronic frequency division to output a full-frequency audio signal. In this example, if the U204 is output alone, the U205& U206 are disconnected, and a single-channel to series power amplifier chip TPA32 is formed to be bridge-connected and output to the subwoofer.

The operational amplifier U208A performs middle and low frequency division, Q is-6 db, cutoff frequency is determined by C269 and (R269+ internal resistance), corner frequency is determined by R270/C270, gain is determined by R270/R269, and DRC function can also be handled. The high-pass low-frequency cut-off frequency in the circuit is formed by the following ranges: regulating within 20 Hz-3 KHz. U208B performs high frequency division with Q value of-6 db, cutoff frequency determined by C259 and (R271+ internal resistance), breakover frequency determined by R273/C275, gain determined by R273/R271, high pass low frequency cutoff frequency determined by the range: 3 KHz-20 KHz, at which time U208A & B will form an unprocessed, theoretically horizontally linear, full audio signal. While U208A and U208B divide the medium and high frequency electronically. If C270 of U208A is changed to 47P-100P, the whole passband of U208A will be changed to 20 Hz-20 KHz full-band audio signal. Meanwhile, the C259 of the U208B is changed into the 4.7U/16V integral passband, and the integral passband is changed into a full-band audio signal of 20Hz to 20 KHz.

Through the above analysis, the present invention can switch the audio signal processed by the U207A & B with the audio signal switch SW 2. Namely, through the design of related multi-section analog electronic frequency division, the same EQ control, Q value control, HI PASS, L0 PASS, BY PASS, DRC, ANC control, sound effect control and other functions of the digital DSP are obtained, and the switching between the PRE AUDIO signal processed BY the analog effect of the digital DSP and the FLATAUDIO AUDIO signal which is not processed and has a theoretical passing frequency band of a horizontal AUDIO signal is achieved. The FLAT Audio signal is processed by the U208A & B unit, and the full-frequency AUDIO signal output of two channels is realized by adjusting the peripheral difference number of the U208A & B unit. Meanwhile, any unit of the U208A & B can output full-frequency audio signals to the series power amplifier chip TPA32 to carry out power frequency division output.

As shown in fig. 5 and 7, in this example, a multifunctional output condition setting module is disposed at the M1 pin and the M2 pin of the power amplifier chip U302, and includes resistors R376 to R379, wherein one ends of the resistor R376 and the resistor R377 are respectively connected to the pin 3M1 of the power amplifier chip U302, one ends of the resistor R378 and the resistor R379 are respectively connected to the pin 4M2 of the power amplifier chip U302, the other ends of the resistor R376 and the resistor R378 are grounded, and the other ends of the resistor R377 and the resistor R379 are respectively connected to the pin 11DVDD of the power amplifier chip U302.

The multifunctional output condition setting module further comprises a resistor R360 and a resistor R351, wherein one end of the resistor R360 is connected with a signal INPUT pin 16INPUT _ C pin of the power amplifier chip U302, one end of the resistor R351 is connected with a signal INPUT pin 17INPUT _ D pin of the power amplifier chip U302, and the other ends of the resistor R360 and the resistor R351 are respectively grounded.

As shown in fig. 8-11, in this embodiment, the PIN port is controlled by changing the power amplifier chip TPA3245/TPA3251/TPA3255 related modes: the INPUT functions of the M1 pin, the M2 pin and the INPUT INPUT _ A/INPUT _ B/INPUT _ C/INPUT _ D are as follows: a.1 channel full or subwoofer output. And B.2 channel output. And C.2.1 channel output. And D.4 channel output.

The working principle of the method is explained in detail as follows:

a: single channel

As shown in FIG. 8, M2 is set high by resistor R379 connected to 11PIN/R378NC, and R377NC/R376 is connected to ground. The INPUT _ C/INPUT _ D INPUT is disconnected, and the 16PIN/17PIN is grounded through the R360/R351. Thus, the setting of the output condition of the single-channel power amplifier is completed. Differential signals are INPUT through INPUT _ a and INPUT _ B. Namely, the low-frequency differential audio signal can be connected, and the full-frequency single-channel differential audio signal can also be connected. The power amplifier chip TPA3245/TPA3251/TPA3255 outputs related single-channel power audio.

B.2 channel output

As shown in FIG. 9, R378/R376 is grounded through resistors R377/R379NC, and/MI// M2 is lowered through R360/R351 NC. Thus, the setting of the output condition of the dual-channel power amplifier is completed. Two paths of differential signals are INPUT through INPUT _ A/INPUT _ B and INPUT _ C/INPUT _ D. Namely, the PRE AUDIO differential AUDIO signal can be connected, and the FLAT AUDIO differential AUDIO signal can be connected. The power amplifier chip TPA3245/TPA3251/TPA3255 outputs related two-channel power audio.

C.2.1 channel output

As shown in fig. 10, two-channel non-differential audio signals are INPUT, and differential low-frequency signals are INPUT through INPUT _ a and INPUT _ B. Thus, the 2.1 channel power amplifier output condition setting is completed. The power amplifier chip TPA3245/TPA3251/TPA3255 outputs related 2.1 power audio.

D.4 channel output

As shown in FIG. 11, the resistor R378/R376NC, R377/R379 connected to 11PIN, makes M1/M2 high. The non-differential audio signal is INPUT through R360/R351NC and INPUT _ B/INPUT _ BB/INPUT _ D and INPUT _ DD. Thus, the 4-channel power amplifier output condition setting is completed. Power amplifier chip TPA3245/TPA3251/TPA3255 outputs related 4-way power audio

From the above analysis, it can be seen that: the invention can realize the treatments of electronic frequency division, DRC control and the like by carrying out relevant pre-treatment on the pre-circuit, and achieves the beneficial effect of multi-conversion of power output aiming at the switching treatment of the multifunctional output modes of the TPA3255 series power amplifier IC, thereby ensuring that the same circuit of the invention is compatible with the TPA3255 series power amplifier IC and greatly reducing the research and development cost and the production cost of a company.

The above-described embodiments are intended to be illustrative, and not restrictive, of the invention, and all changes that come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

1. The circuit for switching the TPA3255 series power amplifier IC multifunctional output is characterized in that: the system comprises a pre-processing circuit and a power amplifying circuit, wherein the output end of the power amplifying circuit is connected with a loudspeaker, the pre-processing circuit comprises a signal input module connected with an input signal, a DRC control module connected with the output end of the signal input module, a first pre-frequency dividing module and a second pre-frequency dividing module which are respectively connected with the output end of the DRC control module, and an audio signal switch, the selection end of the audio signal switch is respectively connected with the output end of the first pre-frequency dividing module and the output end of the second pre-frequency dividing module, and the normally-connected end of the audio signal switch is connected with the input end of the power amplifying circuit;

2. The circuit for the switching of the TPA3255 series power amplifier IC multifunctional output according to claim 1, wherein: the first PRE-frequency division module is used for outputting a PRE AUDIO signal processed by a digital DSP analog effect, and the second PRE-frequency division module is used for outputting a FLAT AUDIO signal which is not processed and has a horizontal AUDIO signal passing frequency band.

3. The circuit for the switching of the TPA3255 series power amplifier IC multifunctional output according to claim 2, wherein: the first preposed frequency division module comprises three frequency division branches and frequency amplification units respectively connected with output ends of the three frequency division branches, the three frequency division branches are respectively used for dividing input frequency signals into high-frequency, medium-frequency and low-frequency sections, each frequency division branch comprises more than one series-connected BY PASS circuit, and each BY PASS circuit is composed of a two-step high-PASS circuit and a two-step low-PASS circuit which are connected in series.

4. The circuit for TPA3255 series power amplifier IC multifunctional output switching according to claim 3, wherein: the frequency amplification unit comprises a power amplifier U207, the power amplifier U207 comprises a power amplifier unit U207A and a power amplifier unit U207B, wherein,

5. The circuit for TPA3255 series power amplifier IC multifunctional output switching according to claim 4, wherein: the second pre-frequency division module comprises a first frequency division branch and a second frequency division branch, wherein the first frequency division branch outputs a low-medium frequency FLAT AUDIO signal, and the second frequency division branch outputs a high-frequency FLAT AUDIO signal.

6. The circuit for TPA3255 series power amplifier IC multifunctional output switching according to claim 5, wherein: the audio signal switching switch includes switches SW2-a and SW2-B, wherein,

two selection ends of the switch SW2-A are respectively connected with the output end of the middle and low frequency FLATAUDIO audio signal and the output end of the middle and low frequency PREAUDIO audio amplification signal, the normally connected end of the switch SW2-A outputs the middle and low frequency signal,

two selection ends of the switch SW2-B are respectively connected with the high-frequency FLAT AUDIO signal output end and the high-frequency PREAUDIO AUDIO amplification signal output end, and the normally-connected end of the switch SW2-B outputs a high-frequency signal.

7. The circuit for TPA3255 series power amplifier IC multifunctional output switching according to claim 6, wherein: and a resistor R154 is also arranged at the normally connected end of the switch SW2-A and the normally connected end of the switch SW 2-B.

8. The circuit for TPA3255 series power amplifier IC multifunctional output switching according to claim 7, wherein: the output processing module converts the medium-low frequency signal and the high-frequency signal output by the pre-processing circuit into six paths of signals which are respectively connected with 4 input pins of a power amplifier chip U302, wherein,

9. The circuit for TPA3255 series power amplifier IC multifunctional output switching according to claim 8, wherein: the multifunctional output condition setting module comprises resistors R376-R379, wherein one ends of the resistor R376 and the resistor R377 are respectively connected with a pin 3M1 of the power amplifier chip U302, one ends of the resistor R378 and the resistor R379 are respectively connected with a pin 4M2 of the power amplifier chip U302, the other ends of the resistor R376 and the resistor R378 are grounded, and the other ends of the resistor R377 and the resistor R379 are respectively connected with a pin 11DVDD of the power amplifier chip U302.

10. The circuit for TPA3255 series power amplifier IC multifunctional output switching according to claim 9, wherein: the multifunctional output condition setting module further comprises a resistor R360 and a resistor R351, wherein one end of the resistor R360 is connected with a signal INPUT pin 16INPUT _ C pin of the power amplifier chip U302, one end of the resistor R351 is connected with a signal INPUT pin 17INPUT _ D pin of the power amplifier chip U302, and the other ends of the resistor R360 and the resistor R351 are respectively grounded.