CN221240474U - Shutdown mute circuit of power amplifier integrated circuit - Google Patents

Abstract

The utility model relates to a shutdown mute circuit of a power amplifier integrated circuit, which comprises a PNP triode Q4, NPN triodes Q6 and Q9, a power amplifier board U8, a startup delay circuit, a voltage stabilizing diode ZD1, resistors R60, R35, R36 and R39, wherein an emitter of the Q4 is connected with one end of the R35 and the U8, a collector of the Q4 is connected with the startup delay circuit, the other end of the R35 is respectively connected with a base electrode of one end Q4 of the R60 and one end of the R36, the other end of the R60 is connected with a base electrode of the Q9, an emitter of the Q9 is grounded, a collector of the Q9 is respectively connected with a cathode of the startup delay circuit, ZD1 and the U8, the other end of the R36 is connected with a collector of the Q6, and an emitter of the Q6 is grounded, and the base electrode of the Q6 is connected with one end of the resistor R39. The shutdown silencing circuit of the power amplifier integrated circuit realizes the product silencing at the shutdown moment, does not need to be additionally provided with a relay with larger volume and a singlechip which needs to be programmed, has the advantages of low cost of required materials and small volume, and also avoids the direct current output by the power amplifier integrated circuit from damaging the loudspeaker voice coil.

Description

Shutdown mute circuit of power amplifier integrated circuit

Technical Field

The utility model relates to the technical field of power amplifier circuits, in particular to a shutdown mute circuit of a power amplifier integrated circuit.

Background

When the power amplifier integrated circuit is applied, many products directly connect the output end of the power amplifier with the loudspeaker, so as to reduce the cost, but the following problems exist: (1) When the power amplifier is used, a consumer is powered off instantly, because potential abrupt change exists in the integrated circuit, direct-current voltage is easily output at the output end of the power amplifier integrated circuit, and after the loudspeaker converts the voltage into sound, the sound of collision is easily heard, so that bad experience is brought to the consumer; (2) When the dc voltage exceeds a certain level, the voice coil inside the horn may be damaged.

Therefore, for the occasion with higher requirement, a Relay is added between the output end of the power amplifier integrated circuit and the loudspeaker for control, as shown in fig. 1, a Relay is added between the 4 th pin of the output end of the 'LM 1875' power amplifier integrated circuit and the loudspeaker for controlling the on and off of the output end of the power amplifier integrated circuit and the loudspeaker: when the loudspeaker is powered off, the loudspeaker is disconnected firstly, the output end of the power amplifier integrated circuit is cut off from the loudspeaker, the direct-current voltage at the output end of the integrated circuit cannot be output to the loudspeaker, the loudspeaker is prevented from generating a 'bump' sound during the power off, and the voice coil inside the loudspeaker is prevented from being damaged by the direct-current voltage. This requires adding control circuitry to the relay. The relay is large in size, occupies a larger space after being added with a control circuit, and meanwhile, the cost is greatly increased; or the power amplifier integrated circuit with the MUTE function is selected, the pin is controlled by the singlechip to realize shutdown MUTE, as shown in fig. 2, the MUTE pin is added to part of the power amplifier integrated circuit, and the power amplifier integrated circuit is controlled to realize shutdown MUTE function by controlling the pin. As shown in fig. two, the 22 nd pin of the TDA7850 power amplifier integrated circuit is a "MUTE" pin, and when the pin is at a low level, the power amplifier integrated circuit is in a "MUTE" state. Therefore, at the moment of shutting down the product, the pin is in a low level state, so that shutdown 'silence' can be realized and the voice coil in the loudspeaker can be prevented from being damaged. Therefore, a control circuit is needed to be added to the pin, and the pin is commonly matched with a singlechip control circuit. However, the singlechip also needs to occupy a certain space, and meanwhile, the singlechip needs to be programmed.

Accordingly, the prior art has shortcomings and needs improvement.

Disclosure of utility model

Aiming at the defects existing in the prior art, the utility model aims to provide a shutdown mute circuit of a power amplifier integrated circuit.

In order to achieve the above objective, the present utility model provides a shutdown mute circuit of an integrated circuit of a power amplifier, which comprises a PNP triode Q4, NPN triodes Q6 and Q9, a power amplifier board U8, a startup delay circuit, a zener diode ZD1, resistors R60, R35, R36, and R39, wherein the emitter of Q4 is connected with one end of R35 and U8, the collector of Q4 is connected with the startup delay circuit, the other end of R35 is connected with the base of one end Q4 and one end of R36 of R60, the other end of R60 is connected with the base of Q9, the emitter of Q9 is grounded, the collector of Q9 is connected with the cathode of the startup delay circuit, ZD1 and U8, the other end of R36 is connected with the collector of Q6, the emitter of Q6 is grounded, and the base of Q6 is connected with one end of resistor R39.

Preferably, the start-up delay circuit includes a resistor R57, a capacitor C49, and a diode D4, wherein the collector of Q4 is connected to one end of R57 and the cathode of D4, the anode of D4 is connected to the other end of R57, one end of C49, the cathode of ZD1, and the collector of Q9, and the other end of C49 is connected to the anode of ZD1 and grounded.

Preferably, the shutdown and mute circuit of the power amplifier integrated circuit further comprises a filter circuit, wherein the filter circuit comprises a resistor R40 and a capacitor C55, and the base electrodes of the Q6 are respectively connected with one end of the resistor R40 and one end of the capacitor C55, and the other end of the resistor R40 and the other end of the capacitor C55 are grounded.

Preferably, the model number of Q4 is B1260.

Preferably, the Q6 is of type B1898.

Preferably, the model of Q9 is C2412.

Preferably, the resistance value of R35 is 10kΩ.

Compared with the prior art, the utility model has the beneficial effects that:

The control level is led out to connect with the mute pin of the power amplifier integrated circuit by utilizing the high-low variation characteristic of the triode pin potential, so that the product is muted in the shutdown moment, a relay with larger volume and a singlechip which needs programming are not needed to be additionally arranged, and the loudspeaker voice coil is low in material cost, convenient to purchase and small in size, and meanwhile, the direct current output by the power amplifier integrated circuit is prevented from damaging the loudspeaker voice coil.

Drawings

In order to more clearly illustrate the solution of the present utility model, a brief description will be given below of the drawings required for the description of the embodiments of the present utility model, it being apparent that the drawings in the following description are some embodiments of the present utility model, and that other drawings may be obtained from these drawings without the exercise of inventive effort for a person of ordinary skill in the art.

Fig. 1 shows a shutdown mute circuit with a relay added to the market.

Fig. 2 shows a shutdown mute circuit added with a singlechip in the market.

Fig. 3 is a shutdown mute circuit of a power amplifier integrated circuit according to the present utility model.

Detailed Description

The preferred embodiments of the present utility model will be described in detail below with reference to the accompanying drawings so that the advantages and features of the present utility model can be more easily understood by those skilled in the art, thereby making clear and defining the scope of the present utility model. It will be apparent that the described embodiments are only some, but not all, embodiments of the utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to fall within the scope of the utility model.

The terms "comprising" and "having" and any variations thereof in the description of the utility model and the claims and the description of the drawings above are intended to cover a non-exclusive inclusion. The terms first, second and the like in the description and in the claims or in the above-described figures, are used for distinguishing between different objects and not necessarily for describing a sequential or chronological order.

Referring to fig. 3, the utility model provides a shutdown mute circuit of an integrated circuit of a power amplifier, which comprises a PNP triode Q4, NPN triode Q6, Q9, a power amplifier board U8, a startup delay circuit, a zener diode ZD1, resistors R60, R35, R36, R39 and a filter circuit, wherein the emitter of Q4 is connected with one end of R35 and U8, the collector of Q4 is connected with the startup delay circuit, the other end of R35 is connected with the base of one end Q4 and one end of R36 of R60, the other end of R60 is connected with the base of Q9, the emitter of Q9 is grounded, the collector of Q9 is connected with the cathode of the startup delay circuit, ZD1 and U8, the other end of R36 is connected with the collector of Q6, the base of Q6 is grounded, the filter circuit comprises a resistor R40, a capacitor C55, the base of Q6 is connected with one end of R40 and one end of C55, and the other end of C55 is grounded. The other end of R39 is connected with the product control port, and the emitter of Q4 is also connected with the product total power supply port; q4 and Q6 form an electronic switch.

Preferably, Q4 is model B1260; q6 is model B1898; q9 has a model C2412R35 of 10KΩ; the model of U8 is TDA7850, and the collector of Q9 is specifically connected with the 22 nd MUTE end of U8; the filter circuit is used for filtering.

Further, the start-up delay circuit comprises a resistor R57, a capacitor C49 and a diode D4, wherein the collector of the Q4 is respectively connected with one end of the R57 and the cathode of the D4, the anode of the D4 is respectively connected with the other end of the R57, one end of the C49, the cathode of the ZD1 and the collector of the Q9, and the other end of the C49 is connected with the anode of the ZD1 and grounded.

When the product is started, the product control port is at a high level, the Q6 is conducted, the base electrode of the Q4 is pulled down, the Q4 is conducted, the collector electrode of the Q4 outputs a high level, and the U8 works after the startup level is impacted through the startup delay circuit, so that startup silence is realized, and the startup voltage is stabilized at 4.7V by ZD1 so as to avoid damaging the U8; when the product is shut down, the product control port is at a low level, the Q6 is cut off, the Q4 base electrode is at a high level, the product control port is connected to the Q9 base electrode through the R60, the Q9 is conducted, the 22 nd mute pin of the U8 is pulled down immediately, and the U8 is in a mute state at the moment, so that the shutdown 'mute' function is realized.

Compared with the prior art, the utility model has the beneficial effects that:

The control level is led out to be connected with the mute pin of the power amplifier integrated circuit by utilizing the high-low variation characteristic of the triode pin potential, so that the product is muted at the moment of shutdown. The power amplifier can realize mute during shutdown, does not need to be additionally provided with a relay with larger volume and a singlechip which needs to be programmed, has the advantages of low cost of required materials, convenient purchase and small volume, and simultaneously avoids direct current output by the power amplifier integrated circuit from damaging the loudspeaker voice coil.

The foregoing is merely illustrative of the present utility model and is not to be construed as limiting thereof; although the utility model has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced with equivalents; all equivalent structures or equivalent flow changes made by the specification and the attached drawings of the utility model or directly or indirectly applied to other related technical fields are included in the protection scope of the utility model.

Claims (7)

1. A shutdown mute circuit of a power amplifier integrated circuit is characterized in that: the power amplifier comprises a PNP type triode Q4, NPN type triode Q6, Q9, a power amplifier board U8, a startup delay circuit, a voltage stabilizing diode ZD1, resistors R60, R35, R36 and R39, wherein an emitter of the Q4 is connected with one end of the R35 and the U8, a collector of the Q4 is connected with the startup delay circuit, the other end of the R35 is respectively connected with a base electrode of one end Q4 of the R60 and one end of the R36, the other end of the R60 is connected with a base electrode of the Q9, an emitter of the Q9 is grounded, a collector of the Q9 is respectively connected with a cathode of the startup delay circuit, a cathode of the ZD1 and the U8, the other end of the R36 is connected with a collector of the Q6, and an emitter of the Q6 is grounded, and a base electrode of the Q6 is connected with one end of the resistor R39.

2. The shutdown mute circuit of the power amplifier integrated circuit of claim 1, wherein: the start-up delay circuit comprises a resistor R57, a capacitor C49 and a diode D4, wherein the collector of the Q4 is respectively connected with one end of the R57 and the cathode of the D4, the anode of the D4 is respectively connected with the other end of the R57, one end of the C49, the cathode of the ZD1 and the collector of the Q9, and the other end of the C49 is connected with the anode of the ZD1 and grounded.

3. The shutdown mute circuit of the power amplifier integrated circuit of claim 1, wherein: the shutdown mute circuit of the power amplifier integrated circuit further comprises a filter circuit, wherein the filter circuit comprises a resistor R40 and a capacitor C55, and the base electrodes of the Q6 are respectively connected with one end of the resistor R40 and one end of the capacitor C55, and the other end of the resistor R40 and the other end of the capacitor C55 are grounded.

4. The shutdown mute circuit of the power amplifier integrated circuit of claim 1, wherein: the model number of Q4 is B1260.

5. The shutdown mute circuit of the power amplifier integrated circuit of claim 1, wherein: the model of Q6 is B1898.

6. The shutdown mute circuit of the power amplifier integrated circuit of claim 1, wherein: the model of Q9 is C2412.

7. The shutdown mute circuit of the power amplifier integrated circuit of claim 1, wherein: the resistance value of R35 is 10KΩ.