Driving circuit for voice isolation output of special transformer terminal

Abstract

The invention is applicable to the field of electronic circuits, and provides a driving circuit for voice isolation output of a special transformer terminal, which comprises a level conversion circuit, a signal transmitting circuit and an isolation output circuit, and is characterized in that the level conversion circuit is electrically connected with a signal pin of a transmitting chip and is used for realizing level matching of communication signals; the output end of the signal sending circuit is connected with the input end of the isolation output circuit, the output end of the isolation output circuit is connected with the loudspeaker interface, and the isolation output circuit is used for achieving isolation transmission of voice signals. And the requirement on the driving capability of the chip pin is low, and the waveform distortion phenomenon can be avoided.

Description

Technical Field

[0001] This invention relates to the field of signal driving technology, and in particular to a driving circuit for voice isolation output of a dedicated transformer terminal. Background Technology

[0002] As a crucial piece of equipment in the power system, the dedicated transformer terminal (power-specific transformer monitoring terminal) needs to provide alarm prompts (such as overvoltage, overload, and fault status prompts) through voice output functionality. Because the dedicated transformer terminal involves high-voltage circuits internally, electrical isolation must be implemented for the voice signal output to ensure equipment safety and the stability of the voice output circuit.

[0003] Traditional voice isolation output solutions mainly fall into two categories: one is an architecture of "optical isolation + demodulation circuit + power amplifier circuit". Optical isolation suffers from poor linearity and is greatly affected by temperature drift, and the multi-stage circuitry leads to complex structure and high cost. The other is a "digital isolation + DAC conversion" solution, which digitizes the analog voice signal and then transmits it in isolation, followed by digital-to-analog conversion to restore it. This solution suffers from large signal delay and poor adaptability, and the cost of digital chips is relatively high.

[0004] Therefore, it is necessary to design a dedicated transformer terminal voice isolation output driver circuit that is simple in structure, low in cost, reliable in isolation, and can guarantee voice quality.

[0005] Technical effect

[0006] This invention features a simplified structure, reducing the number of components by more than 50% compared to traditional solutions, significantly lowering costs. The cost of core components is reduced by 30%-50%. It is suitable for industrial temperature environments and can operate stably under an industrial-grade temperature range of -40℃ to 80℃ and an isolation withstand voltage of ≥2000VAC. It boasts superior performance indicators, with a communication rate of 100kHz to 400kHz, signal delay of <10ms, and voice distortion rate of <5%. Summary of the Invention

[0007] This invention addresses the shortcomings and defects of existing technologies by providing a driving circuit for voice isolation output in dedicated transformer terminals. It solves the problems of complex structure, low isolation reliability, susceptibility to strong electrical noise interference leading to internal circuit damage and voice distortion in traditional driving circuits.

[0008] The objective of this invention can be achieved through the following technical solutions:

[0009] A driving circuit for voice isolation output of a dedicated transformer terminal is characterized in that it includes a level conversion circuit, a signal transmission circuit, and an isolation output circuit. The level conversion circuit is electrically connected to the signal pin of the transmitting chip to achieve level matching of the communication signal. The output terminal of the signal transmission circuit is connected to the input of the isolation output circuit, and the output of the isolation output circuit is connected to the speaker interface to achieve isolated transmission of the voice signal.

[0010] Furthermore, the level conversion circuit is mainly composed of a transistor and a MOSFET. The emitter of the transistor is the unidirectional communication signal input terminal, and the MOSFET is the bidirectional communication terminal. A fast recovery diode is connected in parallel between its drain and source. The source of the MOSFET is the positive signal input terminal, and the drain is the negative signal input terminal.

[0011] Furthermore, the main body of the signal transmission circuit is an integrated chip D1 that supports IIC command configuration and has PWM voice output function. The integrated chip D1 integrates a high-frequency modulation module and a power amplifier module. After receiving the command through the IIC bus, the output terminal of the modulation module outputs a high-frequency modulation signal to modulate the voice analog signal onto the high-frequency carrier. Then, the specified voice signal is amplified by the power amplifier module and output in PWM form, which can directly drive a small speaker.

[0012] Furthermore, the series-connected capacitors C5 and C6 and the isolation transformer T1; one end of capacitors C5 and C6 is electrically connected to the output terminal of the signal transmitting circuit, and the other end is electrically connected to the input terminal of the isolation transformer T1, and the output side of the isolation transformer T1 is electrically connected to the speaker interface.

[0013] Furthermore, the isolation transformer T1 has a turns ratio of 1:1, and the insulation withstand voltage between its primary and secondary windings is not less than 2000VAC. The loudspeaker is connected to the secondary winding of the 1:1 isolation transformer and is used to receive the high-frequency modulated signal transmitted through isolation, and to filter out the high-frequency carrier and restore the voice signal by using its own low-pass filtering characteristics to achieve sound production.

[0014] The beneficial effects of this invention are as follows: it realizes the driving of the entire voice circuit by one IIC signal. The host computer IIC signal is converted into a signal that can be recognized by the voice chip through the level conversion circuit. After the signal is input, the corresponding audio file is selected for output. The output signal is transmitted to the speaker after passing through a 1:1 isolation transformer. The entire circuit has low component cost, stable operation, can achieve isolated output, and is compatible with industrial-grade operating temperature. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings:

[0016] Figure 1 This is a schematic diagram of a driving circuit for voice isolation output of a dedicated transformer terminal according to an embodiment of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and do not limit the scope of the invention.

[0018] like Figure 1 As shown, a driving circuit for voice isolation output of a special transformer terminal includes a level conversion circuit, a signal transmission circuit, and an isolation output circuit. The level conversion circuit is electrically connected to the signal pin of the transmitting chip to achieve level matching of the communication signal. The output terminal of the signal transmission circuit is connected to the input of the isolation output circuit, and the output of the isolation output circuit is connected to the speaker interface to achieve isolated transmission of the voice signal.

[0019] The level conversion circuit is mainly composed of transistors and MOSFETs. The emitter of the transistor is the unidirectional communication signal input terminal, and the MOSFET is the bidirectional communication terminal. A fast recovery diode is connected in parallel between its drain and source. The source of the MOSFET is the positive signal input terminal, and the drain is the negative signal input terminal.

[0020] The driving circuit for voice isolation output of a special transformer terminal is characterized in that the main body of the signal transmission circuit is an integrated chip D1 that supports IIC command configuration and has PWM voice output function. The integrated chip D1 integrates a high-frequency modulation module and a power amplifier module. After receiving the command through the IIC bus, the output terminal of the modulation module outputs a high-frequency modulation signal to modulate the voice analog signal onto a high-frequency carrier. Then, the specified voice signal is amplified by the power amplifier module and output in PWM form, which can directly drive a small speaker.

[0021] The driving circuit for voice isolation output of a dedicated transformer terminal is characterized in that the series-connected capacitors C5 and C6 and the isolation transformer T1 are connected in the following way: one end of capacitors C5 and C6 is electrically connected to the output end of the signal transmission circuit, and the other end is electrically connected to the input end of the isolation transformer T1; the output side of the isolation transformer T1 is electrically connected to the speaker interface.

[0022] The isolation transformer T1 has a turns ratio of 1:1, and the insulation withstand voltage between its primary and secondary windings is not less than 2000VAC. The loudspeaker is connected to the secondary winding of the 1:1 isolation transformer and is used to receive the high-frequency modulated signal transmitted through isolation. It uses its own low-pass filtering characteristics to filter out the high-frequency carrier and restore the voice signal to achieve sound production.

[0023] Based on the above solutions, the basic working principle of this invention is as follows:

[0024] Before operation, the audio file to be played needs to be stored in the ROM storage module of the signal transmitting chip in WAV format, and each audio file needs to be uniquely encoded (such as a numerical number or character identifier) ​​so that it can be accurately recalled by instructions later.

[0025] The host computer sends IIC signals, with SCL being unidirectional. When the SCL signal is low, the transistor's Vbe voltage is greater than its turn-on voltage, and the transistor conducts. The SDA signal is bidirectional. When the SDA signal on the main control side is pulled low, the MOSFET's Vgs voltage is greater than its turn-on voltage, and the MOSFET conducts, enabling level conversion. When the SDA-YUYIN signal on the voice chip side is pulled low, the Schottky diode connected in parallel with the MOSFET, due to its fast conduction characteristic, can achieve SDA level conversion from the chip side to the main control side without affecting signal timing. Through this level conversion mechanism, the host computer can issue commands such as voice playback and audio selection to the voice chip.

[0026] When the signal transmitting chip (audio chip) receives the main control command, it calls the corresponding encoded WAV audio file in the ROM, converts it into a PWM format voice signal, and then modulates it through a high-frequency modulation module. The high-frequency modulation module includes a modulation chip and a carrier generation unit. The carrier generation unit generates a high-frequency carrier, and the modulation chip modulates the voice analog signal with the high-frequency carrier. This design avoids the voice signal band by using a specific frequency high-frequency carrier, while matching the high-frequency transmission characteristics of the isolation transformer to reduce signal loss. The modulated signal is input to a 1:1 ratio isolation transformer in the isolation output circuit. The isolation transformer achieves electrical isolation of the voice signal between the primary and secondary windings with a withstand voltage of not less than 2000VAC without degrading sound quality. Finally, it drives an external speaker through a speaker interface. The speaker uses its low-pass filtering characteristics to filter out the high-frequency carrier and restore the voice signal to play the recorded voice content.

[0027] Throughout the entire process, it met the expected design, and the overall circuit structure was relatively simple, with low requirements for drive current, fast response speed, and high communication rate. It could work normally in both high temperature (80℃) and low temperature (-40℃) environments, and it was also inexpensive, making it highly practical.

[0028] The above embodiments are descriptions of specific implementations of the present invention, and not limitations thereof. Those skilled in the art can make various modifications and changes to obtain corresponding equivalent technical solutions without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions should be included in the patent protection scope of the present invention.

Claims

1. A driving circuit for voice isolation output of a dedicated transformer terminal, characterized in that, It includes a level conversion circuit, a signal transmission circuit, and an isolation output circuit. The level conversion circuit is electrically connected to the signal pin of the transmitting chip to achieve level matching of the communication signal. The output terminal of the signal transmission circuit is connected to the input of the isolation output circuit, and the output of the isolation output circuit is connected to the speaker interface to achieve isolated transmission of the voice signal.

2. The driving circuit for voice isolation output of a dedicated transformer terminal according to claim 1, characterized in that, The level conversion circuit is mainly composed of transistors and MOSFETs. The emitter of the transistor is the unidirectional communication signal input terminal, and the MOSFET is the bidirectional communication terminal. A fast recovery diode is connected in parallel between its drain and source. The source of the MOSFET is the positive signal input terminal, and the drain is the negative signal input terminal.

3. The driving circuit for voice isolation output of a dedicated transformer terminal according to claim 1, characterized in that, The main body of the signal transmission circuit is an integrated chip D1 that supports IIC command configuration and has PWM voice output function. The integrated chip D1 integrates a high-frequency modulation module and a power amplifier module. After receiving the command through the IIC bus, the output terminal of the modulation module outputs a high-frequency modulation signal to modulate the voice analog signal onto the high-frequency carrier. Then, the specified voice signal is amplified by the power amplifier module and output in PWM form, which can directly drive a small speaker.

4. The driving circuit for voice isolation output of a dedicated transformer terminal according to claim 1, characterized in that, The series-connected capacitors C5 and C6 and the isolation transformer T1; one end of capacitors C5 and C6 is electrically connected to the output terminal of the signal transmitting circuit, and the other end is electrically connected to the input terminal of the isolation transformer T1, and the output side of the isolation transformer T1 is electrically connected to the speaker interface.

5. A driving circuit for voice isolation output of a dedicated transformer terminal according to claim 1, characterized in that, The isolation transformer T1 has a turns ratio of 1:1, and the insulation withstand voltage between its primary and secondary windings is not less than 2000VAC. The loudspeaker is connected to the secondary winding of the 1:1 isolation transformer and is used to receive the high-frequency modulated signal transmitted through isolation. It uses its own low-pass filtering characteristics to filter out the high-frequency carrier and restore the voice signal to achieve sound production.

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