Voltage limiting circuit

Abstract

The utility model discloses a voltage limiting circuit, and relates to the technical field of circuit control. According to the main technical scheme, the circuit comprises a signal amplification module, a gain constant-voltage amplification module, a rectification and voltage division module, a comparison module and an integration module, wherein the input end of the signal amplification module is used for accessing an audio signal; the input end of the gain constant-voltage amplification module is connected with the input end of the signal amplification module; the input end of the rectification voltage division module is connected with the output end of the gain constant voltage amplification module; the input end of the comparison module is connected with the output end of the rectification and voltage division module; the input end of the integration module is connected with the output end of the comparison module, and the output end of the integration module is connected with the input end of the gain constant-voltage amplification module. Therefore, the purpose of keeping the output of a relatively constant audio signal size so as to realize the voltage limiting effect on the audio signal is achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit control, in particular to a voltage limiting circuit. Background Art

[0002] The voltage limiting circuit in the audio system is mainly used to protect the loudspeaker to prevent the loudspeaker from being damaged by breakdown when the audio output level is too high.

[0003] When the existing compression circuit is activated, the audio signal will suddenly be compressed from a larger signal to a smaller signal, resulting in a sudden change in the volume of the sound. Utility Model Content

[0004] The utility model aims to provide a voltage limiting circuit, which solves the problem that after the current voltage limiting circuit is started, the audio signal is suddenly compressed from a larger signal to a smaller signal, resulting in a sudden change in the volume of the sound.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A voltage limiting circuit includes a signal amplification module, a gain constant voltage amplification module, a rectifier voltage divider module, a comparison module and an integration module, wherein the input end of the signal amplification module is used to receive an audio signal; the input end of the gain constant voltage amplification module is connected to the input end of the signal amplification module; the input end of the rectifier voltage divider module is connected to the output end of the gain constant voltage amplification module; the input end of the comparison module is connected to the output end of the rectifier voltage divider module; the input end of the integration module is connected to the output end of the comparison module, and the output end of the integration module is connected to the input end of the gain constant voltage amplification module.

[0007] A further solution is: the signal amplification module includes a first signal amplification unit and a second signal amplification unit; the first signal amplification unit includes an operational amplifier U10-B, a resistor R94, a resistor R95 and a capacitor C19; pin 6 of the operational amplifier U10-B, one end of the resistor R94, and one end of the capacitor C19 are all used to connect to the audio signal; pin 5 of the operational amplifier U10-B is grounded; pin 7 of the operational amplifier U10-B, the other end of the resistor R94, and the other end of the capacitor C19 are all connected to one end of the resistor R95; the other end of the resistor R95 is connected to the input end of the second signal amplification unit; the output end of the second signal amplification unit is connected to the input end of the gain constant voltage amplification module.

[0008] A further solution is: the second signal amplification unit includes an operational amplifier U10-A, a resistor R48 and a capacitor C15; pin 2 of the operational amplifier U10-A, one end of the resistor R48, and one end of the capacitor C15 are all connected to the other end of the resistor R95; pin 3 of the operational amplifier U10-A is grounded; pin 1 of the operational amplifier U10-A is connected to the other end of the resistor R48, the other end of the capacitor C15, and the input end of the gain constant voltage amplifier module.

[0009] A further solution is: the gain constant voltage amplifier module includes an operational amplifier U5-A, a resistor R52, a resistor R51, a resistor R53, a resistor R54, a capacitor C12 and a field effect transistor T9; pin 2 of the operational amplifier U5-A is connected to one end of the resistor R53, one end of the resistor R54, and one end of the capacitor C12; pin 1 of the operational amplifier U5-A is connected to the other end of the resistor R54, the other end of the capacitor C12, and the input end of the rectifier voltage divider module; pin 3 of the operational amplifier U5-A is grounded; the other end of the resistor R53 is connected to one end of the resistor R52 and one end of the resistor R51; the other end of the resistor R52 is connected to pin 1 of the operational amplifier U10-A; the other end of the resistor R51 is connected to the drain of the field effect transistor T9; the gate of the field effect transistor T9 is connected to the input end of the integration module; and the source of the field effect transistor T9 is grounded.

[0010] A further solution is: the rectifier voltage divider module includes a third signal amplifying unit and a rectifier voltage divider unit; the third signal amplifying unit includes an operational amplifier U6-A, a resistor R55, a resistor R56, a capacitor C11, an electrolytic capacitor EC9 and an electrolytic capacitor EC10; pin 2 of the operational amplifier U6-A is connected to one end of the resistor R56, one end of the capacitor C11 and one end of the resistor R55; pin 3 of the operational amplifier U6-A is grounded; pin 1 of the operational amplifier U6-A is connected to the other end of the resistor R56 The other end of the resistor R55 and the positive electrode of the electrolytic capacitor EC9 are connected to pin 1 of the operational amplifier U5-A; the negative electrode of the electrolytic capacitor EC9 and the negative electrode of the electrolytic capacitor EC10 are used to connect to the subwoofer output socket SUB_OUT; the input end of the rectifier and voltage divider unit are connected to pin 1 of the operational amplifier U6-A and pin 1 of the operational amplifier U5-A; the output end of the rectifier and voltage divider unit is connected to the input end of the comparison module.

[0011] A further solution is: the rectifier voltage divider unit includes a diode group D11, a resistor R92, a resistor R93 and a capacitor C46; the diode group D11 includes two diodes; the two positive poles of the diode group D11 are respectively connected to pin 1 of the operational amplifier U6-A and pin 1 of the operational amplifier U5-A; the two negative poles of the diode group D11 are both connected to one end of the resistor R92; the other end of the resistor R92 is connected to the input end of the comparison module, one end of the resistor R93, and one end of the capacitor C46; the other end of the resistor R93 and the other end of the capacitor C46 are both grounded.

[0012] A further solution is: the comparison module includes an operational amplifier U9-B, a resistor R57, a resistor R73, a resistor R74, a resistor R91, a capacitor C45 and a diode D12; pin 5 of the operational amplifier U9-B is connected to the other end of the resistor R92; pin 7 of the operational amplifier U9-B is connected to the positive electrode of the diode D12; the negative electrode of the diode D12 is connected to the input end of the integration module; pin 6 of the operational amplifier U9-B is connected to one end of the resistor R57, one end of the resistor R73, one end of the resistor R74, and one end of the capacitor C45; the other end of the resistor R57, the other end of the resistor R74, and the other end of the capacitor C45 are all grounded; the other end of the resistor R73 is connected to one end of the resistor R91; and the other end of the resistor R91 is used to connect to VCH.

[0013] A further solution is: the integration module includes a transistor T7, a diode D8, a diode D10, a resistor R63, a resistor R64, a resistor R65, a resistor R66, a resistor R67, a resistor R68, a resistor R69 and an electrolytic capacitor EC17; one end of the resistor R63 and one end of the resistor R64 are both used to connect to 15V+; the other end of the resistor R64 is connected to the positive electrode of the diode D10; the negative electrode of the diode D10 is grounded; the other end of the resistor R63 is connected to the positive electrode of the diode D8; the negative electrode of the diode D8 is connected to the negative electrode of the transistor T7 The collector is connected; the emitter of the transistor T7, one end of the resistor R66, the negative electrode of the electrolytic capacitor EC17, and one end of the resistor R68 are all used to connect to 15V-; the base of the transistor T7 and the other end of the resistor R66 are connected to one end of the resistor R65; the other end of the resistor R65, the positive electrode of the electrolytic capacitor EC17, the other end of the resistor R68, and one end of the resistor R67 are all connected to one end of the resistor R69; the other end of the resistor R67 is connected to the negative electrode of the diode D12; the other end of the resistor R69 is connected to the gate of the field effect transistor T9.

[0014] Compared with the prior art, the beneficial effects of the present invention are:

[0015] When the audio signal is small (the limiter circuit does not work), the gain of the limiter circuit is equal to R54 / (R52+R53), which is approximately 2 times. When the audio signal is large (far exceeding the threshold of the limiter circuit), the gain of the limiter circuit is approximately equal to R54 / R53, which is 91 times. As different audio signals are input, the gain of the variable gain constant voltage amplifier module varies between 2 and 91 times, thereby maintaining a relatively constant output audio signal size and achieving the effect of limiting the audio signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 1 is an electrical block diagram of a voltage limiting circuit in this embodiment;

[0017] Figure 2 FIG. 4 is a circuit topology diagram of a voltage limiting circuit in this embodiment.

[0018] Markings and corresponding parts names in the accompanying drawings:

[0019] 100-Signal amplification module; 200-Gain constant voltage amplification module; 300-Rectification voltage divider module; 400-Comparison module; 500-Integration module. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with the accompanying drawings.

[0021] Embodiment 1: This embodiment provides a voltage limiting circuit, such as Figure 1 As shown, it includes a signal amplification module 100, a gain constant voltage amplification module 200, a rectifier voltage divider module 300, a comparison module 400 and an integration module 500. The input end of the signal amplification module 100 is used to access the audio signal; the input end of the gain constant voltage amplification module 200 is connected to the input end of the signal amplification module 100; the input end of the rectifier voltage divider module 300 is connected to the output end of the gain constant voltage amplification module 200; the input end of the comparison module 400 is connected to the output end of the rectifier voltage divider module 300; the input end of the integration module 500 is connected to the output end of the comparison module 400, and the output end of the integration module 500 is connected to the input end of the gain constant voltage amplification module 200.

[0022] In this embodiment, if Figure 2As shown, the signal amplification module 100 includes a first signal amplification unit and a second signal amplification unit; the first signal amplification unit includes an operational amplifier U10-B, a resistor R94, a resistor R95 and a capacitor C19; pin 6 of the operational amplifier U10-B, one end of the resistor R94 and one end of the capacitor C19 are all used to connect the audio signal; pin 5 of the operational amplifier U10-B is grounded; pin 7 of the operational amplifier U10-B, the other end of the resistor R94 and the other end of the capacitor C19 are all connected to one end of the resistor R95; the other end of the resistor R95 is connected to the input end of the second signal amplification unit; the output end of the second signal amplification unit is connected to the input end of the gain constant voltage amplification module 200.

[0023] In this embodiment, if Figure 2 As shown, the second signal amplification unit includes an operational amplifier U10-A, a resistor R48 and a capacitor C15; pin 2 of the operational amplifier U10-A, one end of the resistor R48, and one end of the capacitor C15 are all connected to the other end of the resistor R95; pin 3 of the operational amplifier U10-A is grounded; pin 1 of the operational amplifier U10-A is connected to the other end of the resistor R48, the other end of the capacitor C15, and the input end of the gain constant voltage amplifier module 200.

[0024] In this embodiment, if Figure 2 As shown, the gain constant voltage amplifier module 200 includes an operational amplifier U5-A, a resistor R52, a resistor R51, a resistor R53, a resistor R54, a capacitor C12 and a field effect transistor T9; pin 2 of the operational amplifier U5-A is connected to one end of the resistor R53, one end of the resistor R54 and one end of the capacitor C12; pin 1 of the operational amplifier U5-A is connected to the other end of the resistor R54, the other end of the capacitor C12 and the input end of the rectifier voltage divider module 300; pin 3 of the operational amplifier U5-A is grounded; the other end of the resistor R53 is connected to one end of the resistor R52 and one end of the resistor R51; the other end of the resistor R52 is connected to pin 1 of the operational amplifier U10-A; the other end of the resistor R51 is connected to the drain of the field effect transistor T9; the gate of the field effect transistor T9 is connected to the input end of the integration module 500; and the source of the field effect transistor T9 is grounded.

[0025] In this embodiment, if Figure 2As shown, the rectifier and voltage divider module 300 includes a third signal amplifying unit and a rectifier and voltage divider unit; the third signal amplifying unit includes an operational amplifier U6-A, a resistor R55, a resistor R56, a capacitor C11, an electrolytic capacitor EC9 and an electrolytic capacitor EC10; pin 2 of the operational amplifier U6-A is connected to one end of the resistor R56, one end of the capacitor C11 and one end of the resistor R55; pin 3 of the operational amplifier U6-A is grounded; pin 1 of the operational amplifier U6-A is connected to the other end of the resistor R56, the capacitor C11 and the electrolytic capacitor EC9 and the electrolytic capacitor EC10. The other end of the capacitor C11 and the positive electrode of the electrolytic capacitor EC10 are connected; the other end of the resistor R55 and the positive electrode of the electrolytic capacitor EC9 are connected to pin 1 of the operational amplifier U5-A; the negative electrode of the electrolytic capacitor EC9 and the negative electrode of the electrolytic capacitor EC10 are used to connect to the subwoofer output socket SUB_OUT; the input end of the rectifier and voltage divider unit are connected to pin 1 of the operational amplifier U6-A and pin 1 of the operational amplifier U5-A; the output end of the rectifier and voltage divider unit is connected to the input end of the comparison module 400.

[0026] In this embodiment, if Figure 2 As shown, the rectifier voltage divider unit includes a diode group D11, a resistor R92, a resistor R93 and a capacitor C46; the diode group D11 includes two diodes; the two positive poles of the diode group D11 are respectively connected to pin 1 of the operational amplifier U6-A and pin 1 of the operational amplifier U5-A; the two negative poles of the diode group D11 are both connected to one end of the resistor R92; the other end of the resistor R92 is connected to the input end of the comparison module 400, one end of the resistor R93, and one end of the capacitor C46; the other end of the resistor R93 and the other end of the capacitor C46 are both grounded.

[0027] In this embodiment, if Figure 2 As shown, the comparison module includes an operational amplifier U9-B, a resistor R57, a resistor R73, a resistor R74, a resistor R91, a capacitor C45 and a diode D12; pin 5 of the operational amplifier U9-B is connected to the other end of the resistor R92; pin 7 of the operational amplifier U9-B is connected to the positive electrode of the diode D12; the negative electrode of the diode D12 is connected to the input end of the integration module 500; pin 6 of the operational amplifier U9-B is connected to one end of the resistor R57, one end of the resistor R73, one end of the resistor R74 and one end of the capacitor C45; the other end of the resistor R57, the other end of the resistor R74 and the other end of the capacitor C45 are all grounded; the other end of the resistor R73 is connected to one end of the resistor R91; and the other end of the resistor R91 is used to connect to VCH.

[0028] Among them, VCH refers to the operating voltage of the power amplifier, usually 65V+.

[0029] In this embodiment, if Figure 2 As shown, the integration module 500 includes a transistor T7, a diode D8, a diode D10, a resistor R63, a resistor R64, a resistor R65, a resistor R66, a resistor R67, a resistor R68, a resistor R69 and an electrolytic capacitor EC17; one end of the resistor R63 and one end of the resistor R64 are both used to connect to 15V+; the other end of the resistor R64 is connected to the positive electrode of the diode D10; the negative electrode of the diode D10 is grounded; the other end of the resistor R63 is connected to the positive electrode of the diode D8; the negative electrode of the diode D8 is connected to the collector of the transistor T7 The electrodes are connected; the emitter of the transistor T7, one end of the resistor R66, the negative electrode of the electrolytic capacitor EC17, and one end of the resistor R68 are all used to connect to 15V-; the base of the transistor T7 and the other end of the resistor R66 are connected to one end of the resistor R65; the other end of the resistor R65, the positive electrode of the electrolytic capacitor EC17, the other end of the resistor R68, and one end of the resistor R67 are all connected to one end of the resistor R69; the other end of the resistor R67 is connected to the negative electrode of the diode D12; the other end of the resistor R69 is connected to the gate of the field effect transistor T9.

[0030] This embodiment provides the working principle of the voltage limiting circuit:

[0031] After being amplified by signal amplifier module 100, the audio signal undergoes full-wave rectification through diode group D11 and is then divided by resistors R92 and R93 before being sent to pin 5 of operational amplifier U9-B. This voltage is then compared with the reference voltage at pin 6 of operational amplifier U9-B (U9-B forms a comparator circuit). The compared audio signal then passes through integrator module 500, consisting of resistors R67, R68, electrolytic capacitor EC17, and R65, to form a DC voltage proportional to the input signal. A portion of this DC voltage drives field-effect transistor T9 through resistor R69, causing its on-state internal resistance (denoted as resistance R0) to change with the DC voltage. Resistors R52, R51, R0 (actually field-effect transistor T9), R53, R54, and operational amplifier U5-A form variable-gain constant-voltage amplifier module 200, enabling the entire circuit to maintain a constant audio signal level. When the audio signal is small (the voltage limiter circuit does not work), the gain of the voltage limiter circuit is equal to R54 / (R52+R53), which is approximately 2 times. When the audio signal is large (far exceeding the threshold of the voltage limiter circuit), the gain of the voltage limiter circuit is approximately equal to R54 / R53, which is 91 times. As different audio signals are input, the gain of the variable gain constant voltage amplifier module 200 varies between 2 and 91 times, thereby maintaining a relatively constant output audio signal size to limit the audio signal.

[0032] Among them, the DC reference voltage of pin 6 of the operational amplifier U9-B mainly determines the size of the output audio signal, and the resistors R92, R93, and R67 have a certain influence on the size of the output audio signal.

[0033] This voltage limiting circuit can maintain a relatively constant audio signal output within an overload range exceeding 20dB, and keep the audio signal distortion low (THD less than 0.05%), thereby effectively protecting the sound system, maintaining high sound fidelity, and reducing sudden sound changes.

[0034] Although the present invention has been described herein with reference to a number of illustrative embodiments thereof, it will be understood that numerous other modifications and implementations may be devised by those skilled in the art that fall within the scope and spirit of the principles disclosed herein. More specifically, within the scope of the present disclosure, the drawings, and the claims, numerous variations and modifications may be made to the components and / or arrangement of the subject combination arrangement. In addition to variations and modifications to the components and / or arrangement, other uses will also be apparent to those skilled in the art.

Claims

1. A voltage limiting circuit, characterized in that: include: A signal amplification module (100), wherein an input end of the signal amplification module (100) is used to receive an audio signal; a gain constant-voltage amplifying module (200), wherein an input end of the gain constant-voltage amplifying module (200) is connected to an input end of the signal amplifying module (100); A rectifier and voltage divider module (300), wherein the input end of the rectifier and voltage divider module (300) is connected to the output end of the gain constant voltage amplification module (200); A comparison module (400), wherein an input end of the comparison module (400) is connected to an output end of the rectification and voltage division module (300); An integration module (500), wherein the input end of the integration module (500) is connected to the output end of the comparison module (400), and the output end of the integration module (500) is connected to the input end of the gain constant voltage amplification module (200).

2. The voltage limiting circuit according to claim 1, wherein: The signal amplification module (100) comprises a first signal amplification unit and a second signal amplification unit; The first signal amplifying unit includes an operational amplifier U10-B, a resistor R94, a resistor R95 and a capacitor C19; Pin 6 of the operational amplifier U10-B, one end of the resistor R94, and one end of the capacitor C19 are all used to receive audio signals; Pin 5 of the operational amplifier U10-B is grounded; Pin 7 of the operational amplifier U10-B, the other end of the resistor R94, and the other end of the capacitor C19 are all connected to one end of the resistor R95; The other end of the resistor R95 is connected to the input end of the second signal amplifying unit; The output end of the second signal amplifying unit is connected to the input end of the gain constant voltage amplifying module (200).

3. The voltage limiting circuit according to claim 2, wherein: The second signal amplifying unit includes an operational amplifier U10-A, a resistor R48 and a capacitor C15; Pin 2 of the operational amplifier U10-A, one end of the resistor R48, and one end of the capacitor C15 are connected to the other end of the resistor R95; Pin 3 of the operational amplifier U10-A is grounded; Pin 1 of the operational amplifier U10-A is connected to the other end of the resistor R48, the other end of the capacitor C15, and the input end of the gain constant voltage amplification module (200).

4. The voltage limiting circuit according to claim 3, wherein: The gain constant voltage amplification module (200) comprises an operational amplifier U5-A, a resistor R52, a resistor R51, a resistor R53, a resistor R54, a capacitor C12 and a field effect transistor T9; Pin 2 of the operational amplifier U5-A is connected to one end of the resistor R53, one end of the resistor R54, and one end of the capacitor C12; Pin 1 of the operational amplifier U5-A is connected to the other end of the resistor R54, the other end of the capacitor C12, and the input end of the rectifier and voltage divider module (300); Pin 3 of the operational amplifier U5-A is grounded; The other end of the resistor R53 is connected to one end of the resistor R52 and one end of the resistor R51; The other end of the resistor R52 is connected to pin 1 of the operational amplifier U10-A; The other end of the resistor R51 is connected to the drain of the field effect transistor T9; The gate of the field effect transistor T9 is connected to the input end of the integration module (500); The source of the field effect transistor T9 is grounded.

5. The voltage limiting circuit according to claim 4, wherein: The rectification and voltage dividing module (300) comprises a third signal amplification unit and a rectification and voltage dividing unit; The third signal amplifying unit includes an operational amplifier U6-A, a resistor R55, a resistor R56, a capacitor C11, an electrolytic capacitor EC9 and an electrolytic capacitor EC10; Pin 2 of the operational amplifier U6-A is connected to one end of the resistor R56, one end of the capacitor C11, and one end of the resistor R55; Pin 3 of the operational amplifier U6-A is grounded; Pin 1 of the operational amplifier U6-A is connected to the other end of the resistor R56, the other end of the capacitor C11, and the positive electrode of the electrolytic capacitor EC10; The other end of the resistor R55 and the positive electrode of the electrolytic capacitor EC9 are connected to pin 1 of the operational amplifier U5-A; The negative electrode of the electrolytic capacitor EC9 and the negative electrode of the electrolytic capacitor EC10 are both used to connect to the subwoofer output socket SUB_OUT; The input end of the rectifier voltage divider unit is connected to pin 1 of the operational amplifier U6-A and pin 1 of the operational amplifier U5-A; The output end of the rectifying and voltage dividing unit is connected to the input end of the comparison module (400).

6. The voltage limiting circuit according to claim 5, wherein: The rectifier voltage divider unit includes a diode group D11, a resistor R92, a resistor R93 and a capacitor C46; The diode group D11 includes two diodes; The two anodes of the diode group D11 are connected to the pin 1 of the operational amplifier U6-A and the pin 1 of the operational amplifier U5-A respectively; Both cathodes of the diode group D11 are connected to one end of the resistor R92; The other end of the resistor R92 is connected to the input end of the comparison module (400), one end of the resistor R93, and one end of the capacitor C46; The other end of the resistor R93 and the other end of the capacitor C46 are both grounded.

7. The voltage limiting circuit according to claim 6, wherein: The comparison module includes an operational amplifier U9-B, a resistor R57, a resistor R73, a resistor R74, a resistor R91, a capacitor C45 and a diode D12; Pin 5 of the operational amplifier U9-B is connected to the other end of the resistor R92; Pin 7 of the operational amplifier U9-B is connected to the anode of the diode D12; The cathode of the diode D12 is connected to the input end of the integration module (500); Pin 6 of the operational amplifier U9-B is connected to one end of the resistor R57, one end of the resistor R73, one end of the resistor R74, and one end of the capacitor C45; The other end of the resistor R57, the other end of the resistor R74, and the other end of the capacitor C45 are all grounded; The other end of the resistor R73 is connected to one end of the resistor R91; The other end of the resistor R91 is connected to VCH.

8. The voltage limiting circuit according to claim 7, wherein: The integration module (500) includes a transistor T7, a diode D8, a diode D10, a resistor R63, a resistor R64, a resistor R65, a resistor R66, a resistor R67, a resistor R68, a resistor R69 and an electrolytic capacitor EC17; One end of the resistor R63 and one end of the resistor R64 are both used to connect to 15V+; The other end of the resistor R64 is connected to the anode of the diode D10; The cathode of the diode D10 is grounded; The other end of the resistor R63 is connected to the anode of the diode D8; The cathode of the diode D8 is connected to the collector of the transistor T7; The emitter of the transistor T7, one end of the resistor R66, the negative electrode of the electrolytic capacitor EC17, and one end of the resistor R68 are all used to connect to 15V-; The base of the transistor T7 and the other end of the resistor R66 are connected to one end of the resistor R65; The other end of the resistor R65, the positive electrode of the electrolytic capacitor EC17, the other end of the resistor R68, and one end of the resistor R67 are all connected to one end of the resistor R69; The other end of the resistor R67 is connected to the cathode of the diode D12; The other end of the resistor R69 is connected to the gate of the field effect transistor T9.

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