Digital audio circuit

Abstract

The utility model discloses a digital audio circuit, comprising an audio modulator circuit used for audio control; the differential signal conversion and amplification circuit is used for converting and amplifying differential signals; the power amplification circuit is used for amplifying power; the power amplifier output control and voltage detection circuit is used for power amplifier output control and voltage detection; the power amplifier output detection circuit is used for power amplifier output detection; the input audio signal feedback circuit is used for inputting circuit feedback of audio signals; the audio controller circuit is connected with the differential signal conversion and amplification circuit; the power amplification circuit is respectively connected with the power amplifier output control and voltage detection circuit and the power amplifier output detection circuit; the power amplification circuit is connected with the input audio signal feedback circuit. The digital audio circuit is high in tone quality, large in power, small in size and convenient to control, and can surround multiple channels. The multi-purpose selection of a user in multiple places is realized.

Description

Technical Field

[0001] The utility model relates to an audio technology, in particular to a digital audio circuit. Background Art

[0002] At present, home or stage audio systems all require signal processing and amplification; however, the present invention uses analog audio signals that are stabilized and filtered, and then amplified through multiple channels to provide output to the back-end, thereby achieving a stable and high-fidelity surround sound effect. This will lead to a significant difference in the customer's listening experience.

[0003] Disadvantages of existing technology:

[0004] Independent research and development based on demand, long production cycle;

[0005] The circuit structure is simple and the working state is unstable;

[0006] Low power, few compatibility options, and few channels. Summary of the invention

[0007] In view of the above problems, the utility model provides a digital audio circuit, which is a Class D high-end high-quality sound amplifier with high sound quality, high power, multi-channel surround, small size and convenient control. It can solve the user's choice of multi-purpose in multiple places, and the output power can cover the fields of stage and home audio and video.

[0008] The technical solution adopted by the utility model is: a digital audio circuit, comprising:

[0009] Audio modulator circuit for audio control;

[0010] A differential signal conversion and amplification circuit, used for converting a differential signal into a single-ended audio signal and amplifying it;

[0011] A power amplifier circuit is used to amplify the input audio signal to a circuit capable of driving an external speaker;

[0012] Amplifier output control and voltage detection circuit, used for amplifier output control and voltage detection feedback to the power supply circuit to prevent overvoltage from damaging the internal circuit;

[0013] A power amplifier output detection circuit, used to detect the power amplifier output and feed it back to the audio modulator circuit to prevent damage to the external speaker;

[0014] An input audio signal feedback circuit is used to control the size of the audio signal after differential conversion;

[0015] The audio modulator circuit is connected to a differential signal conversion and amplification circuit;

[0016] The power amplifier circuit is respectively connected to the power amplifier output control and voltage detection circuit and the power amplifier output detection circuit;

[0017] The power amplifier circuit is connected to the input audio signal feedback circuit.

[0018] Furthermore, the audio modulator circuit mainly includes an audio modulator U500 and its peripheral circuits.

[0019] Furthermore, the differential signal conversion and amplification circuit mainly includes a low-pass filter formed by R100 and C100 and R102 and C102, and a reverse amplification circuit, and the low-pass filter is connected to the reverse amplification circuit.

[0020] Furthermore, the power amplifier circuit mainly includes a driver chip U103 and its peripheral circuits.

[0021] Furthermore, the power amplifier output detection circuit mainly includes a Hall current sensor U104, an adder circuit and a reverse amplifier. The Hall current sensor U104 is respectively connected to the adder circuit and the reverse amplifier, and is used to convert the signal output by the previous power amplifier circuit into a voltage signal through the U104 ACS710 Hall current sensor. The voltage signal is divided into two paths, one of which is converted into a differential signal through an operational amplifier and given to the previous audio modulator U500 chip, and the other is output to an external power supply.

[0022] Furthermore, the input audio signal feedback circuit mainly includes an operational amplifier U100 and an adder circuit, which is used to add the output voltage VS_1 of the power amplifier circuit MOS tube and the inductor terminal voltage CF_1 through a resistor divider and then add them through an adder circuit composed of an operational amplifier, and then add them again with the final output voltage LFFB_1 to offset each other with the differential signal conversion and amplification circuit.

[0023] Advantages of the utility model:

[0024] Compared with the general power amplifiers on the market which have only two fixed channels, the utility model can also be selected from 300W, 600W, and 1250W;

[0025] Small size. Compared with the same power audio amplifier, which needs to reach 1250W*4 channels and has a volume of at least L*W*H=400mm*300mm*100mm, the board size of this solution is only L*W*H=320mm*150mm*80mm.

[0026] Covering a wide range of customers, 300W can be selected for families and schools, 600W can be selected for KTV and some larger squares, and 1250W can be selected for stage areas;

[0027] Strong testability, with many functions integrated into one connector, which can be automatically tested by software, greatly reducing labor costs;

[0028] High integration, ultra-high parameter performance, multi-channel selection, and wide coverage from medium power to high power.

[0029] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and the description thereof are used to explain the present invention and do not constitute an improper limitation on the present invention.

[0031] Figure 1 It is a principle block diagram of a digital audio circuit according to an embodiment of the utility model.

[0032] Figure 2 It is a schematic diagram of an audio control and regulation circuit of an embodiment of the utility model.

[0033] Figure 3 It is a schematic diagram of a differential signal conversion and amplification circuit according to an embodiment of the utility model.

[0034] Figure 4 It is a schematic diagram of a power amplifier circuit of an embodiment of the utility model.

[0035] Figure 5 It is a schematic diagram of a power amplifier output control and voltage detection circuit according to an embodiment of the utility model.

[0036] Figure 6 It is a schematic diagram of a power amplifier output detection circuit according to an embodiment of the utility model.

[0037] Figure 7 It is a schematic diagram of an input audio signal feedback circuit of an embodiment of the utility model. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0039] Terminology explanation:

[0040] A. PWM: dual-channel Class D audio modulator (Audio modulator);

[0041] B. OA: Operational Amplifiers, operational amplifier;

[0042] C. Power amplifier: Multi-channel amplifier, generally refers to dual-channel surround and four-channel surround in the audio system.

[0043] A digital audio circuit, comprising:

[0044] Audio modulator circuit for audio control;

[0045] A differential signal conversion and amplification circuit, used for converting a differential signal into a single-ended audio signal and amplifying it;

[0046] A power amplifier circuit is used to amplify the input audio signal to a circuit capable of driving an external speaker;

[0047] Amplifier output control and voltage detection circuit, used for amplifier output control and voltage detection feedback to the power supply circuit to prevent overvoltage from damaging the internal circuit;

[0048] A power amplifier output detection circuit, used to detect the power amplifier output and feed it back to the audio modulator circuit to prevent damage to the external speaker;

[0049] An input audio signal feedback circuit is used to control the size of the audio signal after differential conversion;

[0050] The audio modulator circuit is connected to a differential signal conversion and amplification circuit;

[0051] The power amplifier circuit is respectively connected to the power amplifier output control and voltage detection circuit and the power amplifier output detection circuit;

[0052] The power amplifier circuit is connected to the input audio signal feedback circuit.

[0053] like Figure 2 As shown, the audio modulator U500 model is SN61112B5DGGR, and its pins 36, 37, 60, and 61 receive the audio signals of the left and right channels respectively, and finally output the differential PWM signals to the power amplifier circuit below through 40, 41, 56, and 57 after calculation and conversion by the internal program. Pins 52 and 53 of U500 are connected to an NTC thermistor to monitor the temperature of the heat sink of the power amplifier circuit to avoid excessive temperature causing output signal distortion. Pins 17 and 18 of U500 control the switching card of the left and right channels, and an external LED light control circuit is connected to realize that the opening status of the left and right channels can be directly viewed without measurement and detection.

[0054] like Figure 3As shown, the signal conversion amplifier circuit passes the differential signal input from the interface through a low-pass filter composed of R100 and C100 and R102 and C102 to limit the interference signals of 16MHz and 8KHz, and inputs the filtered signal to the 2nd and 3rd pins of the MC33079 operational amplifier U405 for differential signal restoration. The reverse amplifier circuit composed of other internal operational amplifiers is then used to filter out the common-mode interference signal in the circuit to improve stability. Because components from different batches will have different final output signals, the adjustable resistor R1108 is added to calibrate the final output signal during production quality inspection.

[0055] like Figure 4 As shown in the figure, after receiving the PWM signal, the U103 (model SI8234BB-D-IS1R) driver chip outputs control signals in turn to control the two FDP26N40 MOS tubes. Since the voltage difference between VCCP and VCCN can reach 314V, it is not suitable for direct driving of MOS. Therefore, the diode voltage regulator circuit composed of R108, R154, D101, and D102 stabilizes the voltage at about 12.4V to facilitate driving of MOS tubes. FB100 and FB102 magnetic beads limit high-frequency signals above 1MHz to ensure stable operation of U103. When turned on, the 15th pin of U103 outputs a high level. The current limiting of R155 and R156 reduces the large current impact at the moment when the MOS tube is turned on. When turned off, the 15th pin outputs a low level. The positive film of the Q105 transistor transmitter is turned on to accelerate the Vgs discharge rate of the MOS tube to ensure the safety of the circuit. The digital power amplifier circuit composed of U103, HS100-E, HS100-B, L100 and other peripheral circuits amplifies and restores the PWM signal with an amplitude of only 5V after conversion by U500 (SN61112B5DGGR) into an audio signal with a higher amplitude voltage and greater power than the input differential signal to drive the external speaker.

[0056] like Figure 5As shown, the network RELAY_CH_1 outputs high and low levels through Q103 and Q102 to control the K100 relay's pull-in and disconnection by means of small current controlling large current. The function of the K100 relay is that when there is an audio signal input in the circuit, the impact current will be generated at the moment when the power amplifier circuit of the previous stage starts to work, which will be guided to GND through R166 to be discharged. After a delay, the network RELAY_CH_1 will output a high level to close the K100 relay to protect the external speaker. When the circuit is powered off or the output of this channel is not needed, the network RELAY_CH_1 is low, so that Q103 and Q102 cannot be turned on, so that the K100 relay coil cannot form a loop, and the internal moving iron piece returns to its position, disconnecting the connection between the power amplifier circuit of the previous stage and the speaker, and allowing the electric energy stored in the power amplifier circuit of the previous stage to be guided to GND through R166 to be discharged. The resistor voltage divider circuit composed of R170, R170A, and R172 inputs the output voltage reduced by 15 times to the voltage follower circuit composed of the U101 operational amplifier circuit and outputs it to the controller to detect the output voltage. Due to the characteristics of the operational amplifier circuit with large input impedance and small output impedance, the voltage after input voltage division will not change due to the change of the output of the operational amplifier circuit to ensure input stability. The output voltage value is equal to the input voltage value. Due to the small output impedance of the voltage follower, when the controller performs ADC sampling, it can have a large enough load capacity and will not affect the output voltage value due to the loop composed of the internal circuit of the ADC. When the operational amplifier outputs 10V, that is, when the peak voltage output to the speaker reaches 150V, the controller will reduce the input signal or control the K100 relay to disconnect and protect the external speaker.

[0057] like Figure 6 As shown in the figure, the signal output by the power amplifier circuit of the previous stage is converted into a voltage signal through the U104 ACS710 Hall current sensor. The voltage signal is divided into two paths. One path is converted into a differential signal through the operational amplifier and sent to the SN61112B5DGGR chip of the previous stage, and the other path is output to the external power supply. Figure 6 In the two operational amplifiers above, R176 and R177 realize resistor voltage division to provide a 2V reference voltage. The voltage signal output by the Hall current sensor and the voltage signal output by the MOS tube of the power amplifier circuit of the previous stage pass through the network VS_1 to the resistor voltage divider circuit composed of R192, R193, and R187 to the adder circuit composed of the operational amplifier above to add the two and pass the output result through the operational amplifier below for 1:1 reverse amplification to form a pair of differential signals to feedback to the SN61112B5DGGR chip. According to different powers. The output to the external power supply is in Figure 6 In the single op amp circuit below, the current and voltage signals output by the previous power amplifier circuit are amplified and transmitted to the external power supply to prevent overcurrent and overvoltage in the circuit.

[0058] like Figure 7 As shown in the figure, the two operational amplifiers of U100 respectively divide the MOS output voltage VS_1 of the power amplifier circuit and the inductor terminal voltage CF_1 through resistors, add them together through the adder formed by the above operational amplifiers, and then add them again with the final output voltage LFFB_1. Figure 3 The differential signal conversion and amplification circuits cancel each other out, preventing the final power amplifier circuit from outputting excessive signals and burning out the circuit and external speakers due to excessive amplitude of the input audio signal.

[0059] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A digital audio circuit, characterized in that: include: Audio modulator circuit for audio control; A differential signal conversion and amplification circuit, used for converting a differential signal into a single-ended audio signal and amplifying it; A power amplifier circuit is used to amplify the input audio signal to a circuit capable of driving an external speaker; Amplifier output control and voltage detection circuit, used for amplifier output control and voltage detection feedback to the power supply circuit to prevent overvoltage from damaging the internal circuit; Amplifier output detection circuit, used to detect the amplifier output and feed it back to the audio modulator circuit to prevent damage to the external speaker; An input audio signal feedback circuit is used to control the size of the audio signal after differential conversion; The audio modulator circuit is connected to a differential signal conversion and amplification circuit; The power amplifier circuit is respectively connected to the power amplifier output control and voltage detection circuit and the power amplifier output detection circuit; The power amplifier circuit is connected to the input audio signal feedback circuit.

2. The digital audio circuit according to claim 1, characterized in that: The audio modulator circuit mainly includes an audio modulator U500 and its peripheral circuits.

3. The digital audio circuit according to claim 1, characterized in that: The differential signal conversion and amplification circuit mainly includes a low-pass filter formed by R100 and C100 and R102 and C102, and a reverse amplification circuit, and the low-pass filter is connected to the reverse amplification circuit.

4. The digital audio circuit according to claim 1, characterized in that: The power amplifier circuit mainly includes a driver chip U103 and its peripheral circuits.

5. The digital audio circuit according to claim 1, characterized in that: The power amplifier output detection circuit mainly includes a Hall current sensor U104, an adder circuit and a reverse amplifier. The Hall current sensor U104 is connected to the adder circuit and the reverse amplifier respectively, and is used to convert the signal output by the power amplifier circuit of the previous stage into a voltage signal through the U104 ACS710 Hall current sensor. The voltage signal is divided into two paths, one of which is converted into a differential signal through an operational amplifier and given to the audio modulator U500 chip of the previous stage, and the other is output to an external power supply.

6. The digital audio circuit according to claim 1, characterized in that: The input audio signal feedback circuit mainly includes an operational amplifier U100 and an adder circuit, which is used to add the output voltage VS_1 of the power amplifier circuit MOS tube and the inductor terminal voltage CF_1 through a resistor divider and then add them through an adder circuit composed of an operational amplifier, and then add them again with the final output voltage LFFB_1 to offset each other with the differential signal conversion and amplification circuit.

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