CN209982469U

CN209982469U - Analog conversion circuit of audio PWM pulse modulation signal

Info

Publication number: CN209982469U
Application number: CN201920934567.4U
Authority: CN
Inventors: 黄世勇
Original assignee: Shenzhen City Jin Westri Electronics Co Ltd
Current assignee: Shenzhen City Jin Westri Electronics Co Ltd
Priority date: 2019-06-20
Filing date: 2019-06-20
Publication date: 2020-01-21
Anticipated expiration: 2029-06-20

Abstract

The utility model discloses an analog conversion circuit of audio frequency PWM pulse modulation signal. The voice control circuit comprises a voice chip, a forward conduction diode and a clamping diode, wherein the PWM pulse output end of the voice chip is connected with a loudspeaker and is connected with the anode of the forward conduction diode through a current-limiting resistor, the cathode of the forward conduction diode is connected with the cathode of the clamping diode and outputs an analog signal through an integrating resistor, the anode of the clamping diode is grounded, a discharge resistor is connected between the integrating resistor and the forward conduction diode and is grounded, and the output end of the integrating resistor is grounded through an integrating capacitor. The utility model discloses a current-limiting resistor, forward conducting diode, clamper diode, discharge resistance, integral resistance and integral capacitance carry out AD conversion to PWM pulse audio signal to with the analog signal output that lasts.

Description

Analog conversion circuit of audio PWM pulse modulation signal

Technical Field

The utility model belongs to the technical field of the electronic circuit technique and specifically relates to an audio frequency PWM pulse modulation signal's analog-to-digital conversion circuit.

Background

With the development of economy and the improvement of technology, products with voice functions are seen everywhere, such as doorbells, intelligent sound boxes, toys and the like, but some of the products only play voice when playing voice, and are monotonous. If can cooperate the pilot lamp when broadcasting sound, follow the music rhythm and carry out synchronous scintillation, make light and sound combine together, reach one kind and dazzle the effect, can promote the selling point and the user experience of product greatly.

However, in most of the speech chips on the market at present, audio signals are pulse modulation signals of PWM, which are digital signals and are difficult to be acquired through an AD (analog-to-digital converter) of a single chip, so that information such as music tempo and volume of the speech chip is difficult to be acquired. Therefore, the flashing effect is realized for the single chip microcomputer, and the synchronization with the music rhythm is difficult. The sound that appears on the present market is synchronous with the flashing light, mostly controls the flashing light through an output foot of pronunciation chip self, and this kind of way can only single control the scintillation of a lamp, can't realize that a plurality of lamps follow the change of music rhythm, comes to be synchronous with the music rhythm through the lamp of lighting different numbers, similar and the effect of stereo set volume strip beat from top to bottom.

Disclosure of Invention

To the deficiencies that exist among the above-mentioned prior art, the utility model aims to provide an audio frequency PWM pulse modulation signal's analog conversion circuit.

In order to achieve the above purpose, the utility model adopts the following technical scheme:

an analog conversion circuit of audio PWM (pulse-width modulation) signals comprises a voice chip, a forward conducting diode and a clamping diode, wherein a PWM pulse end of the voice chip is connected with PWM pulse audio signals and connected with a loudspeaker and is connected with the anode of the forward conducting diode through a current-limiting resistor, the cathode of the forward conducting diode is connected with the cathode of the clamping diode and outputs analog signals through an integrating resistor, the anode of the clamping diode is grounded, a discharging resistor is connected between the integrating resistor and the forward conducting diode and is grounded, and the output end of the integrating resistor is grounded through an integrating capacitor.

Preferably, the forward conducting diode and the clamping diode are both 1N4148 diodes.

Due to the adoption of the scheme, the utility model discloses a current-limiting resistor, forward conduction diode, clamping diode, discharge resistor, integral resistor and integral capacitor carry out AD conversion to PWM pulse audio signal to with lasting analog signal output, wherein, through current-limiting resistor control current, prevent that the electric current is too big, and burn out other components on the circuit; the forward conduction diode is used for preventing the backflow of the analog signal and blocking the backflow of the signal; the clamping diode is utilized to effectively prevent negative pressure; discharging the integrating capacitor by using a discharging resistor to ensure that the analog signal output end has voltage conversion; an integrating circuit is formed by an integrating resistor and an integrating capacitor, so that the PWM pulse audio signal is changed into a continuous analog signal.

Drawings

Fig. 1 is a schematic diagram of the structural principle of the embodiment of the present invention.

Detailed Description

The embodiments of the invention will be described in detail below with reference to the drawings, but the invention can be implemented in many different ways as defined and covered by the claims.

As shown in fig. 1, the analog conversion circuit of the audio PWM pulse modulation signal provided in this embodiment includes a voice chip U3, a forward conducting diode D4, and a clamping diode D6, where the voice chip U3 may be a KS-F6 chip, a PWM pulse end of the voice chip U3 is connected to a PWM pulse audio signal and is connected to a speaker and is connected to an anode of the forward conducting diode D4 through a current limiting resistor R2, a cathode of the forward conducting diode D4 is connected to a cathode of the clamping diode D6 and outputs an analog signal through an integrating resistor R5, an anode of the clamping diode D6 is grounded, a discharging resistor R3 is grounded between the integrating resistor R5 and the forward conducting diode D4, and an output end of the integrating resistor R5 is grounded through an integrating capacitor C5.

During specific work, the current of the PWM pulse audio signal can directly drive a loudspeaker, so that the current of the PWM pulse audio signal is large, the current is limited through the current limiting resistor R2, the PWM pulse audio signal is prevented from burning other elements on a circuit due to the fact that the current is too large, and the resistance value of the current limiting resistor R2 is 470 ohms.

Further, the forward conducting diode D4 is a 1N4148 diode, and when the digital audio signal is converted into an analog signal by the circuit, the analog signal is prevented from flowing back to the audio output terminal, because the audio signal is a PWM modulated pulse signal that is a digital signal and has a signal voltage of either VDD or GND, and when the signal is GND, if there is no forward conducting diode D4, the signal flows back to the audio output terminal, and due to the forward conducting characteristic of the forward conducting diode D4, the forward conducting diode D4 blocks the signal from flowing back.

Furthermore, in the circuit, because the existence of the capacitor can cause the output of the analog signal to have a negative voltage lower than that of the loudspeaker (GNG) and cause the error of the output analog voltage signal, a clamping diode D6 is added, the clamping diode D6 can be used for preventing the negative voltage from occurring in a limited way, the clamping diode D6 is also a 1N4148 diode,

further, due to the existence of the forward conducting diode D4, the whole circuit has no discharging loop, which will cause that the integrating capacitor C5 cannot discharge after being fully charged, the output voltage of the whole circuit will be maintained at the VDD voltage all the time, the voltage of the analog signal output end does not change, and the single chip microcomputer used for receiving the analog signal externally cannot detect the signal. The discharge resistor R3 can consume the extra power to generate voltage variation at the analog signal output terminal. The resistance of the discharge resistor R3 cannot be too small, otherwise it may cause too fast discharge and weak voltage change at the output terminal, so the value is about 100K.

Furthermore, the integrating resistor R5 and the integrating capacitor C5 form an integrating circuit, so that the pulse modulation signal output by the PWM end can be converted into a continuous analog signal, the PWM signal at the audio output end is a pulse modulation signal and is a discontinuous digital signal, the voltage has only two values of VDD and GND, and the voltage can be converted into a continuous analog voltage signal between GND and VDD through the integrating circuit formed by the integrating resistor R5 and the integrating capacitor C5.

The above is only the preferred embodiment of the present invention, and not the scope of the present invention, all the equivalent structures or equivalent flow changes made by the contents of the specification and the drawings or the direct or indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An analog conversion circuit of an audio PWM pulse modulation signal, characterized in that: the voice control circuit comprises a voice chip, a forward conducting diode and a clamping diode, wherein the PWM pulse output end of the voice chip is connected with a loudspeaker and is connected with the anode of the forward conducting diode through a current-limiting resistor, the cathode of the forward conducting diode is connected with the cathode of the clamping diode and outputs an analog signal through an integrating resistor, the anode of the clamping diode is grounded, a discharging resistor is connected between the integrating resistor and the forward conducting diode and is grounded, and the output end of the integrating resistor is grounded through an integrating capacitor.

2. An analog conversion circuit for an audio PWM pulse modulated signal according to claim 1, wherein: the forward conducting diode and the clamping diode are both 1N4148 diodes.