Power-off Detection Circuit, Power Control Circuit and Audio Device

Abstract

The present application relates to a power-down detection circuit, a power control circuit and an audio device. The power-down detection circuit includes: a triode Q2, a storage capacitor C6, a diode D3 and a diode D4; the diode D3 is connected to the base of the triode Q2, and the base is grounded through a resistor R2, and the storage capacitor C6 is connected to the emitter of the triode Q2; the diode D3 is connected between the bases of the triode Q2, and the collector of the triode Q2 outputs a detection signal; in the powered-on state, the standby power supply charges the storage capacitor C6 through the diode D4 and provides a voltage to the base of the triode Q2 through the diode D3; when power is down, the storage capacitor C6 provides a voltage to the emitter of the triode Q2, the base voltage of the triode Q2 drops, and when a voltage difference is generated between the base and the collector of the triode Q2, the triode Q2 conducts, and the collector of the triode Q2 outputs a level signal; this solution realizes the rapid detection of power-down, facilitates timely control of the power amplifier to cut off power when power is down, and plays a role in protecting the power amplifier and the speaker.

Description

Technical Field

[0001] The present application relates to the field of audio technologies, and particularly to a power-off detection circuit, a power control circuit, and an audio device. Background Art

[0002] In an audio device, in order to protect a power amplifier and a speaker, delay start and power-off protection designs are often adopted. When the system is powered on and off, by first turning off the power amplifier and muting the speaker, it is ensured that the impact signal at the front stage of the power amplifier will not be amplified to the speaker, protecting the safety of the power amplifier and also preventing the speaker from being damaged due to excessive impact signals.

[0003] In conventional technologies, generally, delay start and power-off technologies detect the AC power supply. When the AC power supply used as the power supply is powered on or off, rapid detection is performed, and relevant turn-off and mute controls are carried out. However, in many audio devices using a switching power supply, the detection circuit for the AC power is very complex, which is not conducive to the detection. When directly detecting the DC power supply, the power-off voltage of the power supply will drop slowly, and it is easy for the impact signal to reach the power amplifier and the speaker before it has time to be completely powered off, thus failing to achieve the function of protecting the power amplifier and the speaker. Summary of the Invention

[0004] The present application provides a power-off detection circuit, a power control circuit, and an audio device, which can quickly detect when the standby power supply in the audio device is powered off and timely control the power amplifier to cut off the power.

[0005] A power-off detection circuit includes: a triode Q2, a storage capacitor C6, a diode D3, and a diode D4;

[0006] The diode D4 is connected between the standby power supply and the emitter of the triode Q2, and the storage capacitor C6 is connected to the emitter of the triode Q2; the diode D3 is connected to the base of the triode Q2, the base of the triode Q2 is grounded through a resistor R2, and the collector of the triode Q2 outputs a detection signal;

[0007] In the powered-on state, the standby power supply charges the storage capacitor C6 through the diode D4 and provides a voltage to the base of the triode Q2 through the diode D3;

[0008] In the power-off state, the storage capacitor C6 provides a voltage to the emitter of the triode Q2, the base voltage of the triode Q2 drops, and when a voltage difference is generated between the base and the collector of the triode Q2, the triode Q2 conducts, and the collector of the triode Q2 outputs a level signal.

[0009] In one embodiment, the power-down detection circuit further includes an isolation circuit connected between the base of the triode Q2 and the power supply, for suppressing the noise in the control power supply.

[0010] In one embodiment, the power-down detection circuit further includes a resistor R5 connected to the base of the triode Q2;

[0011] The isolation circuit includes an optocoupler. One output terminal of the optocoupler is connected to a diode D3, and the other output terminal is connected to the base of the triode Q2 through the resistor R5.

[0012] A power control circuit includes the above-mentioned power-down detection circuit, a charging circuit, a discharging circuit, and an execution circuit;

[0013] The charging circuit is connected to the standby power supply through the diode D3; the output terminal of the charging circuit is respectively connected to the discharging circuit and the execution circuit; the execution circuit is connected to the power amplifier;

[0014] When power is on, the standby power supply charges the charging circuit through the diode D3. After the charging circuit has a charging delay, it delays to start the execution circuit to turn on the power amplifier;

[0015] When power is off, the power-down detection circuit controls the discharging circuit to quickly discharge the charging circuit, and quickly starts the execution circuit to turn off the power amplifier.

[0016] In one embodiment, the charging circuit includes a resistor R3 and an energy storage capacitor C1; the discharging circuit includes a resistor R7 and a triode Q3; the execution circuit includes a resistor R6, a resistor R9, and a triode Q1;

[0017] The energy storage capacitor C1 is connected to the standby power supply through the resistor R3; the energy storage capacitor C1 is connected to the base of the triode Q1 through the resistor R9;

[0018] The collector of the triode Q3 is connected to the energy storage capacitor C1. The base of the triode Q3 is connected to the emitter of the triode Q2 through the resistor R7; the emitter of the triode Q3 is grounded;

[0019] The collector of the triode Q1 is connected to the standby power supply through the resistor R6, and the collector of the triode Q1 is connected to the power amplifier.

[0020] In one embodiment, the charging circuit further includes a resistor R4 and an energy storage capacitor C3; wherein, the energy storage capacitor C1 and the energy storage capacitor C3 are connected in parallel to achieve the charging delay function.

[0021] In one embodiment, an energy storage capacitor C7 and a resistor R8 are respectively connected between the base and the emitter of the triode Q3.

[0022] In one embodiment, the base of the triode Q1 is also connected to a plurality of cascaded diodes for generating a voltage drop on the base of the triode Q1.

[0023] An audio device includes: at least one of the above-mentioned power control circuits, a power amplifier, and a speaker.

[0024] In one embodiment, the device includes at least two power control circuits connected in parallel; wherein, the output terminal of at least one power control circuit is connected to the mute circuit of the power amplifier, and the output terminal of the other power control circuit is connected to the power switch of the power amplifier.

[0025] The above technical solution of the present application has the following beneficial effects:

[0026] (1) The power-off detection circuit of the present application is unidirectionally powered by the diode D3 and the diode D4 respectively. The diode D4 and the energy storage capacitor C6 form a power supply. When the power is off, the energy storage capacitor C6 can provide voltage to the emitter of the triode Q2. The base of the triode Q2 slowly drops in voltage due to being connected to the standby power supply. Thus, a voltage difference is generated between the base and the collector of the triode Q2, causing the triode Q2 to conduct, and the collector of the triode Q2 outputs a level signal; this technical solution realizes the rapid detection of the power-off of the standby power supply, facilitating the timely control of the power amplifier to cut off the power when the standby power supply in the audio device is powered off, and playing a role in protecting the power amplifier and the speaker.

[0027] (2) The power control circuit of the present application, through the power-off detection circuit, the charging circuit, the discharging circuit, and the execution circuit, when powered on, can be charged by the charging circuit, and the execution circuit is delayed to start to turn on the power amplifier, playing a role in protecting the power amplifier and the speaker; when powered off, the power-off detection circuit can quickly detect the voltage change state of the standby power supply, control the discharging circuit to discharge the charging circuit, thereby controlling the execution circuit to control the power amplifier to turn off, playing a role in protecting the power amplifier and the speaker.

[0028] Further, the base of the triode Q1 of the execution circuit is connected in series with a plurality of cascaded diodes, so that a voltage drop can be generated at the base of the triode Q1, increasing the voltage value of the PN junction of the base and delaying the charging delay time.

[0029] (3) The audio device of the present application can include a power control circuit, a power amplifier, and a speaker. Through the power control circuit, the power-off of the standby power supply can be quickly detected, and the power amplifier can be timely controlled to cut off the power when the DC power supply is powered off, playing a role in protecting the power amplifier and the speaker.

[0030] Further, through a plurality of power control circuits connected in parallel, the power amplifier can be subjected to mute control and power switch control, etc., to ensure the safety of the power amplifier and the speaker.

[0031] Additional aspects and advantages of the present application will be given in part in the following description, will become apparent from the following description, or will be learned through the practice of the present application. Description of the Drawings

[0032] The above-mentioned and / or additional aspects and advantages of the present application will become apparent and easy to understand from the following description of embodiments in conjunction with the drawings, where:

[0033] Figure 1 is a schematic structural diagram of a power-down detection circuit of an embodiment;

[0034] Figure 2 is a schematic structural diagram of a power-down detection circuit of another embodiment;

[0035] Figure 3 is a schematic structural diagram of a power control circuit of an embodiment;

[0036] Figure 4 is a schematic structural diagram of a power control circuit of another embodiment;

[0037] Figure 5 is a schematic structural diagram of an audio device of an embodiment. Detailed Description of the Embodiments

[0038] Embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present application and should not be construed as limiting the present application.

[0039] Those skilled in the art of the present technology can understand that unless specifically stated otherwise, the singular forms "a", "an", "the", and "said" used herein may also include the plural forms. It should be further understood that the term "comprising" used in the specification of the present application means the presence of the described features, integers, steps, operations, but does not exclude the presence or addition of one or more other features, integers, steps, operations.

[0040] The technical solution of this application is mainly used in audio devices, in scenarios where power-off signals need to be detected when protecting power amplifiers and speakers. For example, this technical solution can be applied to an audio-video integrated machine, which is an audio-video processing device with highly integrated software and hardware, multi-scenario applications, and convenient on-site deployment. Its power supply system is connected to the power supply line of the power supply (such as AC 220V) through a power plug, and then separate switching power supplies are designed on each circuit board for power supply. Therefore, a standby power supply will be used for power supply. After the device is powered on, the power amplifier board enters the standby state, and the power amplifier board uses the standby power supply. Therefore, the standby power supply is used for example in the following text of this application. In actual applications, the standby power supply can refer to any power supply that provides electrical energy to the power amplifier. By adopting the technical solution of this application, the standby power supply can be directly inspected, thereby providing a timely control signal for protecting the power amplifier and speakers.

[0041] Reference Figure 1 , Figure 1 Figure 7 is a schematic structural diagram of a power-off detection circuit of an embodiment. As shown in the figure, the power-off detection circuit includes: a triode Q2, a storage capacitor C6, a diode D3, and a diode D4; the diode D4 is connected between the standby power supply and the emitter of the triode Q2, and the storage capacitor C6 is connected to the emitter of the triode Q2; the diode D3 is connected to the base of the triode Q2, the base of the triode Q2 is grounded through a resistor R2, and the collector of the triode Q2 outputs a detection signal.

[0042] In the powered-on state, the standby power supply charges the storage capacitor C6 through the diode D4, and provides voltage to the base of the triode Q2 through the diode D3; when power-off occurs, the storage capacitor C6 provides voltage to the emitter of the triode Q2, the base voltage of the triode Q2 drops, and when a voltage difference is generated between the base and the collector of the triode Q2, the triode Q2 conducts, and the collector of the triode Q2 outputs a level signal.

[0043] The power-off detection circuit of this embodiment is powered unidirectionally through the diodes D3 and D4 respectively. The diode D4 and the storage capacitor C6 form a power supply. When power-off occurs, the storage capacitor C6 can provide voltage to the emitter of the triode Q2. The base of the triode Q2 slowly drops in voltage due to its connection to the standby power supply. As a result, a voltage difference is generated between the base and the collector of the triode Q2, causing the triode Q2 to conduct. The collector of the triode Q2 outputs a level signal, realizing the rapid detection of the power-off of the standby power supply, facilitating the timely control of the power amplifier to cut off power when the standby power supply of the audio device is powered off, and playing a role in protecting the power amplifier and speakers.

[0044] The following elaborates more embodiments of the technical solution of this application.

[0045] Reference Figure 2 , Figure 2It is a schematic structural diagram of a power-down detection circuit of another embodiment.

[0046] In this embodiment, the power-down detection circuit may further include: an isolation circuit connected between the base of the triode Q2 and the power supply, for suppressing the noise in the control power supply. The base of the triode Q2 is connected to the resistor R5; the isolation circuit includes an optocoupler, one output terminal 4 of the optocoupler is connected to the diode D3, and the other output terminal 3 is connected to the base of the triode Q2 through the resistor R5.

[0047] As shown in the figure, an energy storage capacitor C4 and a capacitor C5 may also be connected at the front end of the isolation circuit, and the input terminal of the optocoupler is connected to the host system through the resistor R1. For example, the host system outputs a 5V power supply, and the standby power supply STANDBY POWER is 5V DC power.

[0048] In specific operation: The host system outputs a 5V power supply to control the optocoupler U1 to conduct. The standby power supply STANDBY POWER outputs a 5V DC power supply to the base of the triode Q5 through the diode D3. On the other path, the standby power supply STANDBY POWER outputs a 5V DC power supply to charge the energy storage capacitor C6 through the diode D4 and provides a 5V voltage to the emitter of the triode Q2; at this time, the triode Q2 is in a cut-off state. When a power-down occurs, the host system shuts down the control power supply. At this time, the standby power supply STANDBY POWER slowly drops; the standby power supply STANDBY POWER slowly drops the voltage to the base of the triode Q2 through the diode D3, the optocoupler U1, and the resistor R5; the energy storage capacitor C6 maintains a power supply close to 5V, the diode D4 is reversely cut off, and the energy storage capacitor C6 provides a voltage close to 5V to the triode Q2. When a voltage difference is generated between the base and the collector of the triode Q2, when the voltage difference is a certain value (such as 0.2 - 0.3V for a germanium triode, 0.5 - 0.6V for a silicon triode), the triode Q2 conducts, and at this time, a level signal can be output from the emitter, so as to quickly detect the power-down state of the standby power supply STANDBY POWER.

[0049] The embodiments of the power control circuit are described below. The power control circuit of the present application is mainly used to perform relevant control on the power-on and power-off of the audio device to protect the safety of the power amplifier and the speaker.

[0050] Refer to Figure 3 , Figure 3 It is a schematic structural diagram of a power control circuit of an embodiment; as shown in the figure, the power control circuit of this embodiment mainly includes: a power-down detection circuit, a charging circuit, a discharging circuit, and an execution circuit; the charging circuit is connected to the standby power supply through the diode D3; the output terminal of the charging circuit is respectively connected to the discharging circuit and the execution circuit; the execution circuit is connected to the power amplifier.

[0051] When powered on, the standby power supply charges the charging circuit through diode D3. After a charging delay in the charging circuit, the execution circuit is delayed to start and turn on the power amplifier. When powered off, the power-off detection circuit controls the discharge circuit to quickly discharge the charging circuit, and the execution circuit is quickly started to turn off the power amplifier.

[0052] The power supply control circuit of this embodiment, through the power-off detection circuit, charging circuit, discharge circuit and execution circuit, when powered on, can be charged by the charging circuit, and the execution circuit is delayed to start to turn on the power amplifier, playing a role in protecting the power amplifier and speaker; when powered off, the power-off detection circuit can quickly detect the voltage change state of the standby power supply, control the discharge circuit to discharge the charging circuit, so as to control the execution circuit to control the power amplifier to turn off, playing a role in protecting the power amplifier and speaker.

[0053] The following describes more embodiments of the power supply control circuit.

[0054] Reference Figure 4 , Figure 4 is a schematic structural diagram of the power supply control circuit of another embodiment; in this embodiment, the charging circuit includes resistor R3 and energy storage capacitor C1; the discharge circuit includes resistor R7 and triode Q3; the execution circuit includes resistor R6, resistor R9 and triode Q1.

[0055] Among them, the energy storage capacitor C1 is connected to the standby power supply through resistor R3; the energy storage capacitor C1 is connected to the base of triode Q1 through resistor R9; the collector of triode Q3 is connected to the energy storage capacitor C1, the base of triode Q3 is connected to the emitter of triode Q2 through resistor R7; the emitter of triode Q3 is grounded; the collector of triode Q1 is connected to the standby power supply through resistor R6, and the collector of triode Q1 is connected to the power amplifier.

[0056] Furthermore, in this embodiment, the charging circuit may further include resistor R4 and energy storage capacitor C3; among them, the energy storage capacitor C1 and the energy storage capacitor C3 are connected in parallel to achieve the charging delay function. A energy storage capacitor C7 and a resistor R8 can be respectively connected between the base and the emitter of the triode Q3. That is, two groups of energy storage capacitors can be used for charging to increase the charging time.

[0057] In specific operation:

[0058] When powered on, since the transistor Q1 is connected to the standby power supply STANDBY POWER through the pull-up resistor R6, the transistor Q1 is in the cut-off state when powered on. At this time, the output terminal POWER ON outputs a high-level signal to the power amplifier, turning off the power amplifier and the speaker; at the same time, the standby power supply STANDBY POWER slowly charges the energy storage capacitor C1 through the diode D3, the photocoupler U1, and the resistor R3, and slowly charges the energy storage capacitor C3 through the resistor R4. After the energy storage capacitors C1 and C3 are fully charged, a voltage is provided to the base of the transistor Q1 through the resistor R9; when the voltage reaches a certain value, the transistor Q1 is turned on, and at this time, the output terminal POWERON outputs a low-level signal to the power amplifier, starting the power amplifier and the speaker; thereby, the function of delaying the start of the power amplifier and the speaker is realized, and the power amplifier and the speaker can be protected when the power is turned on.

[0059] When power is off (such as shutdown operation, accidental power off, etc.), energy storage capacitor C6 provides voltage to the emitter of transistor Q2, and the base voltage of transistor Q2 drops. When a voltage difference is generated between the base and collector of transistor Q2, transistor Q2 is turned on, and the collector of transistor Q2 outputs a high-level signal to the base of transistor Q3. Transistor Q3 is turned on. Since the emitter of transistor Q3 is grounded, energy storage capacitors C1 and C3 are quickly discharged through transistor Q3. After discharge, the base voltage of transistor Q1 drops rapidly. At this time, transistor Q1 quickly enters the cut-off state. Correspondingly, the output terminal POWER ON outputs a high-level signal to the power amplifier, and the power amplifier and the speaker are quickly turned off; thereby avoiding the situation where the standby power supply voltage drops slowly and cannot be detected in time, and ensuring that the power amplifier and the speaker are completely powered off before the impact signal reaches the power amplifier and the speaker, thereby protecting the power amplifier and the speaker.

[0060] In one embodiment, the base of the transistor Q1 is further connected to a plurality of cascaded diodes to generate a voltage drop on the base of the transistor Q1. Figure 4 As shown in the figure, a diode D1, a diode D2 and a diode D5 are added. Of course, different numbers of diodes can also be cascaded according to actual conditions.

[0061] In this embodiment, a voltage drop can be generated on the base of transistor Q1 by cascading diodes, because when the energy storage capacitors C1 and C3 are charged, the more fully charged, the longer the delay, and the transistor Q1 can be turned on when the base voltage of the transistor is generally low. In order to prevent the transistor Q1 from turning on too early, multiple diodes are cascaded to divide the voltage, increase the voltage value of the PN junction of the base, and delay the charging delay time. In this way, when the energy storage capacitors C1 and C3 are charged to a higher voltage, the transistor Q1 will be turned on, and a longer delay time can be set. Compared with the use of voltage-stabilizing diodes, this technical solution has a simple circuit and achieves more accurate delay control.

[0062] Embodiments of the audio device of the present application will be described below.

[0063] The audio device provided by the present application includes at least one power control circuit, a power amplifier, and a speaker. As an embodiment, the audio device includes at least two power control circuits connected in parallel; wherein, the output end of at least one power control circuit is connected to the mute circuit of the power amplifier, and the output end of the other power control circuit is connected to the power switch of the power amplifier.

[0064] As Figure 5 shown, Figure 5 is a schematic structural diagram of an audio device according to an embodiment; it can be seen from the figure that the output terminal POWER ON of one path of the power control circuit 1 can output a level signal to the power amplifier to control the mute circuit of the power amplifier, so as to mute the speaker and avoid damage to the speaker caused by impact signals. The output terminal MUTE of the other path of the power control circuit 2 can output a level signal to the power amplifier to control the power switch of the power amplifier, turn on / off the power amplifier, and avoid damage to the power amplifier caused by impact signals.

[0065] The audio device of this embodiment can quickly detect the power failure of the standby power supply through the power control circuit, and timely control the power amplifier to cut off the power when the DC power supply fails, playing a role in protecting the power amplifier and the speaker. Moreover, multiple power control circuits connected in parallel can control the mute control and power switch of the power amplifier, etc., to ensure the safety of the power amplifier and the speaker.

[0066] The above are only some embodiments of the present application. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present application, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present application.

Claims

1. A power control circuit, characterized in that, It includes a power-off detection circuit, a charging circuit, a discharging circuit and an execution circuit; The power-off detection circuit includes: a triode Q2, a storage capacitor C6, a diode D3 and a diode D4; the diode D4 is connected between the standby power supply and the emitter of the triode Q2, and the storage capacitor C6 is connected to the emitter of the triode Q2; the diode D3 is connected to the base of the triode Q2, the base of the triode Q2 is grounded through a resistor R2, and the collector of the triode Q2 outputs a detection signal; The charging circuit is connected to the standby power supply through the diode D3; the charging circuit includes a resistor R3 and a storage capacitor C1; the discharging circuit includes a resistor R7 and a triode Q3; the execution circuit includes a resistor R6, a resistor R9 and a triode Q1; The storage capacitor C1 is connected to the standby power supply through a resistor R3; the storage capacitor C1 is connected to the base of the triode Q1 through a resistor R9; The collector of the triode Q3 is connected to the storage capacitor C1, the base of the triode Q3 is connected to the emitter of the triode Q2 through a resistor R7; the emitter of the triode Q3 is grounded; The collector of the triode Q1 is connected to the standby power supply through a resistor R6, and the collector of the triode Q1 is connected to the power amplifier; When powered on, the standby power supply charges the storage capacitor C6 through the diode D4, and provides voltage to the base of the triode Q2 through the diode D3; the standby power supply charges the charging circuit through the diode D3, and after charging delay, the execution circuit is delayed to start to turn on the power amplifier; When powered off, the storage capacitor C6 provides voltage to the emitter of the triode Q2, the base voltage of the triode Q2 drops, when a voltage difference is generated between the base and the collector of the triode Q2, the triode Q2 conducts, and the collector of the triode Q2 outputs a level signal; the power-off detection circuit controls the discharging circuit to quickly discharge the charging circuit, and quickly starts the execution circuit to turn off the power amplifier.

2. The power control circuit according to claim 1, wherein It further includes: An isolation circuit connected between the base of the triode Q2 and the power supply, which is used to suppress the noise in the control power supply.

3. The power control circuit according to claim 2, wherein It further includes a resistor R5 connected to the base of the triode Q2; The isolation circuit includes an optocoupler, one output terminal of the optocoupler is connected to the diode D3, and the other output terminal is connected to the base of the triode Q2 through a resistor R5.

4. The power control circuit according to claim 1, wherein The charging circuit further includes a resistor R4 and a storage capacitor C3; wherein, the storage capacitor C1 and the storage capacitor C3 are connected in parallel to realize the charging delay function.

5. The power control circuit according to claim 1, wherein A storage capacitor C7 and a resistor R8 are respectively connected between the base and the emitter of the triode Q3.

6. The power control circuit according to claim 1, wherein The base of the triode Q1 is also connected to a cascade of multiple diodes, which is used to generate a voltage drop on the base of the triode Q1.

7. An audio device, characterized in that, It includes: At least one power control circuit according to any one of claims 1 to 6, a power amplifier and a speaker.

8. The audio device according to claim 7, wherein The device includes at least two power control circuits connected in parallel; wherein, the output terminal of at least one power control circuit is connected to the mute circuit of the power amplifier, and the output terminal of the other power control circuit is connected to the power switch of the power amplifier.

Images