Circuit for eliminating startup and shutdown impact sound of audio equipment

Abstract

The utility model discloses a circuit for eliminating startup and shutdown impact sound of audio equipment, which comprises a triode T1, a base electrode of the triode T1 is connected with a power supply VDD after passing through a resistor R1, an emitting electrode of the triode T1 is connected with the power supply VDD after passing through a resistor R2 and a diode D1, the emitting electrode of the triode T1 is grounded after passing through a resistor R3, the emitting electrode of the triode T1 is grounded after passing through a capacitor C1, and the emitting electrode of the triode T1 is grounded after passing through a resistor R2. A collector electrode of the triode T1 is grounded after passing through a mute pin entry point and a resistor R4, the mute pin entry point is connected with a power supply VDD after passing through a capacitor C2 and a diode D2, and the mute pin entry point is connected with the power supply VDD after passing through a resistor R5 and the diode D2. The circuit for eliminating the startup and shutdown impact sound of the audio equipment is directly connected to the MUTE pin of the audio power amplifier chip, so that the MUTE end is pulled down after a while and the power amplifier outputs at late time when the power is on, and the MUTE end is set up immediately and the power amplifier is shut down immediately when the power is off, and the startup and shutdown impact sound is prevented.

Description

Technical Field

[0001] The utility model relates to a circuit, and more precisely, to a circuit for eliminating the impact sound during the power - on and power - off of an audio device. Background Art

[0002] Most audio power amplifier chips have a MUTE pin. When MUTE is at a high level, the power amplifier is in an automatic mute state. When the MUTE pin is at a low level, the mute is cancelled and the power amplifier works normally. However, if the MUTE pin is directly connected to a low level, during power - on, since it takes time for the power amplifier circuit to establish, there will be unstable output during the process of the circuit establishing a stable operating point, resulting in a popping sound. Also, during power - off, the same situation occurs. Since the minimum operating voltages of various components in the power amplifier are different, one may hear the music gradually weaken instead of the output being immediately turned off, which affects the user experience. Summary of the Utility Model

[0003] Based on this, it is necessary to provide a circuit for eliminating the impact sound during the power - on and power - off of an audio device in view of the above - mentioned technical problems.

[0004] To solve the above - mentioned technical problems, the utility model adopts the following technical solutions:

[0005] A circuit for eliminating the impact sound during the power - on and power - off of an audio device, the circuit for eliminating the impact sound during the power - on and power - off of an audio device includes a triode T1. The base of the triode T1 is connected to the power supply VDD through a resistor R1. The emitter of the triode T1 is connected to the power supply VDD through a resistor R2 and a diode D1. The emitter of the triode T1 is grounded through a resistor R3. The emitter of the triode T1 is grounded through a capacitor C1. The collector of the triode T1 is grounded through a mute pin entry point and a resistor R4. The mute pin entry point is connected to the power supply VDD through a capacitor C2 and a diode D2. The mute pin entry point is connected to the power supply VDD through a resistor R5 and a diode D2.

[0006] As a preferred embodiment of the utility model, the mute pin entry point is connected to the MUTE pin of the audio power amplifier chip.

[0007] As a preferred embodiment of the utility model, the triode T1 is a PNP - type triode.

[0008] As a preferred embodiment of the utility model, the anode of the diode D1 is connected to the power supply VDD.

[0009] As a preferred embodiment of the utility model, the anode of the diode D2 is connected to the power supply VDD.

[0010] Compared with the prior art, the utility model has the following beneficial effects:

[0011] The utility model provides a circuit for eliminating the switching impact sound of an audio device. The circuit for eliminating the switching impact sound of the audio device is directly connected to the MUTE pin of the audio power amplifier chip, realizing that the MUTE terminal is pulled low after a while when power is on, so that the power amplifier outputs later, and when power is off, the MUTE is immediately set high, so that the power amplifier is immediately turned off, preventing the thumping sound during switching on and off, with obvious effect and strong practicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] In order to more clearly illustrate the solutions in the utility model, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following described drawings are some embodiments of the utility model. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0013] Figure 1 It is a three-dimensional structure diagram of the circuit for eliminating the switching impact sound of the audio device of the utility model;

[0014] Figure 2 It is a working voltage diagram of the circuit for eliminating the switching impact sound of the audio device of the utility model. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] In order to enable those skilled in the art of this technology to better understand the solutions of the utility model, the following will clearly and completely describe the technical solutions in the embodiments of the utility model with reference to the drawings in the embodiments of the utility model.

[0016] As Figure 1 shown, the circuit for eliminating the switching impact sound of the audio device includes a triode T1. The base of the triode T1 is connected to the power supply VDD through a resistor R1. The emitter of the triode T1 is connected to the power supply VDD through a resistor R2 and a diode D1. The emitter of the triode T1 is grounded through a resistor R3. The emitter of the triode T1 is grounded through a capacitor C1. The collector of the triode T1 enters the ground through a mute pin entry point MUTE and a resistor R4. The mute pin entry point MUTE is connected to the power supply VDD through a capacitor C2 and a diode D2. The mute pin entry point MUTE is connected to the power supply VDD through a resistor R5 and a diode D2.

[0017] It should be noted that the mute pin entry point MUTE is connected to the MUTE pin of the audio power amplifier chip.

[0018] In addition, the triode T1 is a PNP type triode. The anode of the diode D1 is connected to the power supply VDD. The anode of the diode D2 is connected to the power supply VDD.

[0019] The working mode of the circuit for eliminating the impact sound during the power-on and power-off of the audio device will be described below.

[0020] As Figure 2 shown, it is a simulation schematic diagram of the working voltage of the circuit for eliminating the impact sound during the power-on and power-off of the audio device. Among them, the solid line represents the power supply VDD, and the dotted line represents the terminal voltage of the mute pin entry point MUTE.

[0021] At the moment of power-on, the power supply VDD becomes high level. However, the voltage of capacitor C2 cannot change suddenly, similar to a short circuit. At the very beginning moment, the voltage of the mute pin entry point MUTE is slightly lower than that of the power supply VDD and is at high level. Then, capacitor C2 starts to charge, and the terminal voltage of the mute pin entry point MUTE gradually decreases to low level. At this time, the triode T is in the cut-off state.

[0022] At the moment of power-off, the base potential of the triode T drops suddenly, and the emitter potential also drops. However, due to the discharge of capacitor C1, the speed of the emitter voltage drop is slower than that of the base. At a certain moment during the drop process, the triode T changes from the cut-off state to the amplification state, and the collector and emitter currents suddenly increase. The sudden increase in the collector current causes the terminal voltage of the mute pin entry point MUTE to suddenly rise to high level. Therefore, at the moment of power-off, the terminal voltage of the mute pin entry point MUTE suddenly changes to high level first. It should be noted that adjusting the resistance and capacitance values in the circuit can adjust the delay or advance of the mute enable / disable time.

[0023] It should be noted that for some power amplifier chips, when their MUTE pins are at high level, the power amplifier works normally, and when the MUTE is at low level, the power amplifier is in the mute state. A level inversion circuit, such as a triode, can be connected to the MUTE of the designed circuit, and the level is inverted and then output.

[0024] The circuit for eliminating the impact sound during the power-on and power-off of the audio device is directly connected to the MUTE pin of the audio power amplifier chip, realizing that the MUTE terminal is pulled low after a while during power-on, so that the power amplifier outputs later, and the MUTE is immediately set high during power-off, so that the power amplifier is immediately turned off, preventing the thump sound during power-on and power-off, with obvious effect and strong practicability.

[0025] Obviously, the above-described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The preferred embodiments of the present application are given in the drawings, but they do not limit the patent scope of the present application.

Claims

1. An audio device power-on / off impact noise elimination circuit, characterized in that, The described circuit for eliminating the switching impact sound of the audio device includes a triode T1. The base of the triode T1 is connected to the power supply VDD through a resistor R1. The emitter of the triode T1 is connected to the power supply VDD through a resistor R2 and a diode D1. The emitter of the triode T1 is grounded through a resistor R3. The emitter of the triode T1 is grounded through a capacitor C1. The collector of the triode T1 is grounded through a mute pin input point (MUTE) and a resistor R4. The mute pin input point (MUTE) is connected to the power supply VDD through a capacitor C2 and a diode D2. The mute pin input point (MUTE) is connected to the power supply VDD through a resistor R5 and a diode D2.

2. The circuit for eliminating the on / off impact sound of an audio device according to claim 1, wherein The mute pin input point (MUTE) is connected to the MUTE pin of the audio power amplifier chip.

3. The circuit for eliminating the on / off impact sound of an audio device according to claim 1, characterized in that, The triode T1 is a PNP type triode.

4. The circuit for eliminating the switching impact sound of an audio device according to claim 1, characterized in that, The anode of the diode D1 is connected to the power supply VDD.

5. The circuit for eliminating the switching impact sound of an audio device according to claim 1, wherein The anode of the diode D2 is connected to the power supply VDD.

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