Overcurrent Detection Circuit and Digital Power Amplifier Equipment

Abstract

The present application provides an overcurrent detection circuit and a digital power amplifier device, relating to the technical field of digital power amplifiers. The overcurrent detection circuit is connected to a digital power amplifier circuit. In the digital power amplifier circuit, the gate of a field effect transistor is connected to the output end of a pulse signal generation circuit, the source is connected to the power amplifier output end, and the drain is connected to a power supply; the input end of the overcurrent detection circuit is connected to the gate of the field effect transistor, the first detection end is connected to the drain of the field effect transistor, the second detection end is connected to the source of the first field effect transistor, and the first detection end is electrically connected to the input end. The overcurrent detection circuit is configured to output a power amplifier protection signal when the current passing through the field effect transistor detected by the first detection end and the second detection end exceeds a preset value. The embodiments of the present application can achieve timely detection of overcurrent of the field effect transistor, effectively reduce the possibility of damage to the digital power amplifier circuit, and extend the service life of the digital power amplifier circuit.

Description

Technical Field

[0001] This application relates to the technical field of digital power amplifiers. Specifically, this application relates to an overcurrent detection circuit and a digital power amplifier device. Background Art

[0002] A digital power amplifier is an amplifier with characteristics such as low distortion, low noise, and large dynamic range. It is incomparable to traditional power amplifiers in terms of the warmth and coldness of sound quality, resolution, background quietness, and low-frequency shock intensity. Therefore, it is widely used in electronic systems such as home theaters, audio systems, stereo turntables, and servo amplifiers.

[0003] In actual use, a digital power amplifier may have an overcurrent (i.e., excessive current) due to situations such as audio signals, power supplies, or its own abnormal operation. The excessive current can damage the power amplifier transistors (field effect transistors) in the digital power amplifier circuit, resulting in circuit damage. To avoid this situation, it is necessary to promptly detect the overcurrent in the digital circuit for quick handling. Summary of the Invention

[0004] Embodiments of this application provide an overcurrent detection circuit and a digital power amplifier device, which can solve the problem of quickly detecting overcurrent. To achieve this purpose, the embodiments of this application provide the following several solutions.

[0005] According to one aspect of the embodiments of this application, an overcurrent detection circuit is provided. The overcurrent detection circuit is connected to a digital power amplifier circuit. The digital power amplifier circuit includes a pulse signal generation circuit and a field effect transistor that conducts when the input is high. The gate of the field effect transistor is connected to the output terminal of the pulse signal generation circuit, the source is connected to the power amplifier output terminal, and the drain is connected to the power supply;

[0006] The overcurrent detection circuit includes an input terminal, a first detection terminal, and a second detection terminal. The input terminal is connected to the gate of the field effect transistor, the first detection terminal is connected to the drain of the field effect transistor, the second detection terminal is connected to the source of the field effect transistor, and the first detection terminal is electrically connected to the input terminal. The overcurrent detection circuit is configured to output a power amplifier protection signal when it detects that the current passing through the field effect transistor exceeds a preset value through the first detection terminal and the second detection terminal.

[0007] In a possible implementation, the power supply includes a positive power supply and a negative power supply. The output terminals of the digital power amplifier circuit include a first output terminal and a second output terminal. The time periods during which the first output terminal and the second output terminal output high levels in the same PWM cycle are different. The field effect transistors include a first field effect transistor and a second field effect transistor. The gate of the first field effect transistor is connected to the first output terminal, the gate of the second field effect transistor is connected to the second output terminal. The drains of the first field effect transistor and the second field effect transistor are connected to the overcurrent detection circuit, and the drain of the first field effect transistor is connected to the positive power supply, and the drain of the second field effect transistor is connected to the negative power supply.

[0008] In a possible implementation, the overcurrent detection circuit further includes a first detection circuit. The first detection circuit includes a second resistor and a first triode. The first end of the second resistor is connected to the gate of the first field effect transistor and the emitter of the first triode. The second end of the second resistor is connected to the base of the first triode and the source of the first field effect transistor.

[0009] In a possible implementation, the first detection circuit further includes a first diode, a first resistor, a second diode, and a third diode. The anode of the first diode is connected to the second end of the first resistor, the anode of the second diode, the first end of the second resistor, and the anode of the third diode. The cathode of the first diode is connected to the drain of the first field effect transistor. The cathode of the third diode is connected to the first end of the first resistor and the gate of the first field effect transistor. The cathode of the second diode is connected to the emitter of the first triode.

[0010] In a possible implementation, the first detection circuit further includes a fourth diode and a fourth resistor. The anode of the fourth diode is connected to the collector of the first triode, and the cathode of the fourth diode is connected to the first end of the fourth resistor.

[0011] In a possible implementation, the overcurrent detection circuit further includes a second detection circuit. The second detection circuit includes a fifth diode, a second triode, and an eighth resistor. The cathode of the fifth diode is connected to the power amplifier output terminal, and the anode is connected to the base of the second triode, the first end of the eighth resistor, and the gate of the second field effect transistor. The emitter of the second triode is connected to the second end of the eighth resistor and the drain of the second triode.

[0012] In a possible implementation, the second detection circuit further includes: a sixth resistor, a seventh resistor, and an operational amplifier. The first end of the sixth resistor is connected to the collector of the second triode. The second end of the sixth resistor is connected to the first end of the seventh resistor and the inverting input terminal of the operational amplifier. The second end of the seventh resistor is connected to a DC power supply. The non-inverting input terminal of the operational amplifier is grounded.

[0013] In a possible implementation, the second detection circuit further includes a fifth resistor, a sixth diode, and a seventh diode. The first end of the fifth resistor is connected to the gate of the second field effect transistor and the cathode of the sixth diode. The second end of the fifth resistor is connected to the anode of the sixth diode and the first end of the eighth resistor. The anode of the seventh diode is connected to the emitter of the second triode. The cathode of the seventh diode is connected to the second end of the eighth resistor.

[0014] According to one aspect of the embodiments of the present application, a digital power amplifier device is provided. The digital power amplifier device includes a digital power amplifier circuit, a power amplifier protection circuit, and the overcurrent detection circuit as described above. The overcurrent detection circuit is connected to the digital power amplifier circuit, and the output terminal of the overcurrent detection circuit is connected to the power amplifier protection circuit. The power amplifier protection circuit is configured to trigger a power amplifier protection operation after receiving a power amplifier protection signal from the overcurrent detection circuit.

[0015] In a possible implementation, the digital power amplifier circuit further includes a first inductor and a first capacitor. The first end of the first inductor is connected to the source of the field effect transistor. The second end of the first inductor is connected to the power amplifier output terminal and the first end of the first capacitor. The second end of the first capacitor is grounded.

[0016] The beneficial effects brought by the technical solution provided by the embodiments of the present application are as follows:

[0017] The overcurrent detection circuit provided by the present application includes an input terminal, a first detection terminal, and a second detection terminal. The input terminal is connected to the gate of the field effect transistor. The first detection terminal is connected to the drain of the first field effect transistor. The second detection terminal is connected to the source of the first field effect transistor. And the first detection terminal is electrically connected to the input terminal. The overcurrent detection circuit is configured to output a power amplifier protection signal when the current passing through the field effect transistor detected through the first detection terminal and the second detection terminal exceeds a preset value. Therefore, the overcurrent detection circuit of the embodiments of the present application can realize the timely detection of overcurrent of the field effect transistor, effectively protect the digital power amplifier circuit, effectively reduce the possibility of damage to the digital power amplifier circuit, and extend the service life of the digital power amplifier circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] To more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments of the present application.

[0019] Figure 1 It is the structural diagram of the overcurrent detection circuit provided for the embodiments of the present application;

[0020] Figure 2 It is the specific structural diagram of the overcurrent detection circuit provided for the embodiments of the present application;

[0021] Figure 3 It is the circuit diagram of the digital power amplifier circuit provided for the embodiments of the present application;

[0022] Figure 4 It is the circuit diagram of the overcurrent detection circuit provided for the embodiments of the present application;

[0023] Figure 5 It is the structural diagram of the digital power amplifier device provided for the embodiments of the present application.

[0024] Explanation of the reference numerals in the drawings: HO, the first output terminal; LO, the second output terminal; Q1, the first field-effect transistor; Q2, the second field-effect transistor; R2, the second resistor; Q3, the first triode; D1, the first diode; R1, the first resistor; D2, the second diode; D3, the third diode; D4, the fourth diode; R4, the fourth resistor; D5, the fifth diode; Q4, the second triode; R8, the eighth resistor; R6, the sixth resistor; R7, the seventh resistor; U1A, the operational amplifier; R5, the fifth resistor; D6, the sixth diode; D7, the seventh diode; D8, the eighth diode; L1, the first inductor; C1, the first capacitor. Specific embodiments

[0025] The following describes the embodiments of the present application in conjunction with the drawings in the present application. It should be understood that the embodiments described below in conjunction with the drawings are exemplary descriptions for explaining the technical solutions of the embodiments of the present application and do not limit the technical solutions of the embodiments of the present application.

[0026] Those skilled in the art 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 terms "comprising" and "including" used in the embodiments of the present application mean that the corresponding features can be implemented as the presented features, information, data, steps, operations, elements and / or components, but do not exclude being implemented as other features, information, data, steps, operations, elements, components and / or their combinations supported by the technical field of the present application. It should be understood that when we say an element is "connected" or "coupled" to another element, the one element can be directly connected or coupled to the other element, or it can mean that the one element and the other element establish a connection relationship through an intermediate element. In addition, the "connection" or "coupling" used herein may include wireless connection or wireless coupling. The term "and / or" used herein indicates at least one of the items defined by the term, for example, "A and / or B" indicates being implemented as "A", or being implemented as "A", or being implemented as "A and B".

[0027] To make the objectives, technical solutions and advantages of the present application clearer, the following will further describe the embodiments of the present application in detail with reference to the accompanying drawings.

[0028] The technical solutions of the embodiments of the present application and the technical effects produced by the technical solutions of the present application will be described below by describing several exemplary embodiments. It should be noted that the following embodiments can be referred to, learned from or combined with each other. For the same terms, similar features and similar implementation steps in different embodiments, they will not be described repeatedly.

[0029] The overcurrent detection circuit and digital power amplifier device provided by the present application are intended to solve at least one technical problem existing in the prior art.

[0030] In the embodiments of the present application, an overcurrent detection circuit is provided, such as Figures 1 - 4As shown, the overcurrent detection circuit is connected to the digital power amplifier circuit. The digital power amplifier circuit includes a pulse signal generation circuit, a power amplifier output terminal, and a field effect transistor that conducts when the input is high. The gate of the field effect transistor is connected to the output terminal of the pulse signal generation circuit, the source is connected to the power amplifier output terminal, and the drain is connected to the power supply. The overcurrent detection circuit includes an input terminal, a first detection terminal, and a second detection terminal. The input terminal is connected to the gate of the field effect transistor, the first detection terminal is connected to the drain of the field effect transistor, and the second detection terminal is connected to the source of the field effect transistor. Moreover, the first detection terminal is electrically connected to the input terminal. The overcurrent detection circuit is configured to output a power amplifier protection signal when the current passing through the field effect transistor detected by the first detection terminal and the second detection terminal exceeds a preset value. Among them, when a high level is applied to the gate of the field effect transistor, a current loop is formed among the input terminal, the first detection terminal, the second detection terminal, and the field effect transistor, and the overcurrent of the digital power amplifier circuit is detected by detecting the current in this current loop.

[0031] Optionally, the preset value is determined based on the current value of the current passing through the field effect transistor when the digital power amplifier circuit has an overcurrent, and the digital power amplifier circuit is protected by outputting a power amplifier protection signal when the current exceeds the preset value.

[0032] Optionally, the pulse signal generation circuit includes a PWM modulation circuit and a gate drive circuit, and a drive signal for driving the conduction and cutoff of the field effect transistor is output through the PWM modulation circuit and the gate drive circuit, so as to control the conduction and cutoff of the field effect transistor, and an audio signal after power amplification is output at the power amplifier output terminal.

[0033] Optionally, the output terminal of the digital power amplifier circuit includes a first output terminal HO and a second output terminal LO. The power supply includes a positive power supply and a negative power supply. The time periods during which the first output terminal HO and the second output terminal LO output high levels are different in the same pwm cycle. The field effect transistor includes a first field effect transistor Q1 and a second field effect transistor Q2. The gate of the first field effect transistor Q1 is connected to the first output terminal HO, the gate of the second field effect transistor Q2 is connected to the second output terminal LO, and the drains of the first field effect transistor Q1 and the second field effect transistor Q2 are connected to the overcurrent detection circuit. Among them, the drain of the first field effect transistor Q1 is connected to the positive power supply, and the drain of the second field effect transistor Q2 is connected to the negative power supply. The first field effect transistor Q1 serves as the upper half-bridge power amplifier transistor of the digital power amplifier circuit, and the second field effect transistor Q2 serves as the lower half-bridge power amplifier transistor of the digital power amplifier circuit. The upper half-bridge power amplifier transistor and the lower half-bridge power amplifier transistor conduct and cutoff correspondingly based on the level changes of the first output terminal HO and the second output terminal LO.

[0034] Optionally, the overcurrent detection circuit further includes a first detection circuit for detecting overcurrent of the first field-effect transistor Q1. The first detection circuit includes a second resistor R2 and a first triode Q3. The first end of the second resistor R2 is connected to the gate of the first field-effect transistor Q1 and the emitter of the first triode Q3. The second end of the second resistor R2 is connected to the base of the first triode Q3 and the source of the first field-effect transistor Q1. After the first triode Q3 is turned on, an amplifier protection signal is output through the collector of the first triode Q3. The resistance value of the second resistor R2 is determined according to the resistance value after the first field-effect transistor Q1 is turned on and the preset value.

[0035] Optionally, the first detection circuit further includes a first diode D1, a first resistor R1, a second diode D5, and a third diode D3. The anode of the first diode D1 is connected to the second end of the first resistor R1, the anode of the second diode D5, the first end of the second resistor R2, and the anode of the third diode D3. The cathode of the first diode D1 is connected to the drain of the first field-effect transistor Q1. The cathode of the third diode D3 is connected to the first end of the first resistor R1 and the gate of the first field-effect transistor Q1. The cathode of the second diode D5 is connected to the emitter of the first triode Q3.

[0036] Optionally, the first detection circuit further includes a fourth diode D4 and a fourth resistor R4. The anode of the fourth diode D4 is connected to the collector of the first triode Q3. The cathode of the fourth diode D4 is connected to the first end of the fourth resistor R4. The second end of the fourth resistor R4 is connected to the signal receiving end. The signal output from the collector of the first triode Q3 is transmitted to the signal receiving end after passing through the fourth diode D4 and the fourth resistor R4.

[0037] Optionally, the overcurrent detection circuit further includes a second detection circuit for detecting overcurrent of the second field-effect transistor Q2. The second detection circuit includes a fifth diode D5, a second triode Q4, and an eighth resistor R8. The cathode of the fifth diode D5 is connected to the power amplifier output end. The anode is connected to the base of the second triode Q4, the first end of the eighth resistor R8, and the gate of the second field-effect transistor Q2. The emitter of the second triode Q4 is connected to the second end of the eighth resistor R8 and the drain of the second triode Q4.

[0038] Optionally, to ensure that the second detection circuit outputs the same power amplifier protection signal as the first detection circuit, the second detection circuit further includes: a sixth resistor R6, a seventh resistor R7, and an operational amplifier U1A. The first end of the sixth resistor R6 is connected to the collector of the second triode Q4. The second end of the sixth resistor R6 is connected to the first end of the seventh resistor R7 and the inverting input terminal of the operational amplifier U1A. The second end of the seventh resistor R7 is connected to the DC power supply. The non-inverting input terminal of the operational amplifier U1A is grounded. Wherein, the output terminal of the operational amplifier U1A is connected to a signal receiving terminal for receiving the power amplifier protection signal. When the voltage at the inverting input terminal of the operational amplifier U1A is lower than that at the non-inverting input terminal, the output terminal of the operational amplifier U1A outputs a high-level signal, and this high-level signal is transmitted to the signal receiving terminal as the power amplifier protection signal.

[0039] Optionally, the second detection circuit further includes a fifth resistor R5, a sixth diode D6, and a seventh diode D7. The first end of the fifth resistor R5 is connected to the gate of the second field-effect transistor Q2 and the cathode of the sixth diode D6. The second end of the fifth resistor R5 is connected to the anode of the sixth diode D6 and the first end of the eighth resistor R8. The anode of the seventh diode D7 is connected to the emitter of the second triode Q4. The cathode of the seventh diode D7 is connected to the second end of the eighth resistor R8.

[0040] In one embodiment, the second detection circuit further includes an eighth diode D8. The anode of the eighth diode D8 is connected to the output terminal of the operational amplifier U1A. The cathode of the eighth diode D8 is connected to the output terminal of the first detection circuit.

[0041] The following combines Figure 3 、 Figure 4 to illustrate the overcurrent detection circuit of the present application.

[0042] In one embodiment, the signal receiving end is the port PROTECT. The first output end HO is connected to the gate of the first field-effect transistor Q1. The first output end HO takes the pulse node as the reference point. When the first output end HO outputs a low level, the potential difference between the first output end HO and the pulse node is zero, the first field-effect transistor Q1 is turned off, the first diode D1 is reversely cut off, there is no potential difference across the second resistor R2, the first triode Q3 is turned off, the circuit does not operate. When the first output end HO outputs a high level, the first field-effect transistor Q1 is turned on. The first output end HO passes through the first resistor R1, the first diode D1, the source and drain of the first field-effect transistor Q1, and the second resistor R2 is connected in parallel to the first diode D1 and the first field-effect transistor Q1 to form a path. When a large current (the current exceeds the preset value) flows through the first field-effect transistor Q1, the conduction voltage drop of the first field-effect transistor Q1 increases, the second resistor R2 is connected in parallel to the first diode and the first field-effect transistor Q1, the voltage across the second resistor R2 increases, the first triode Q3 is forward-biased from the emitter to the base, the first triode Q3 is turned on, and the collector outputs a power amplifier protection signal. This signal passes through the fourth diode D4 and the fourth resistor R4 to the port PROTCET to start power amplifier protection.

[0043] When the second output end LO outputs a low level, the second output end LO is pulled low with the negative power supply as the reference point, the fifth diode D5 is reversely cut off, there is no potential difference across the eighth resistor R8, the second triode Q4 is turned off, and the circuit does not operate. When the second output end LO outputs a high level, the second field-effect transistor Q2 is turned on, the current flows through the fifth resistor R5, the fifth diode D5, the source and drain of the second field-effect transistor Q2, and the fifth diode D5 is connected in parallel to the eighth resistor R8 and the source-drain of the second field-effect transistor Q2. When a large current flows through the second field-effect transistor Q2, the voltage across the eighth resistor R8 increases, the second triode Q4 is forward-biased from the emitter to the base, the second triode Q4 is turned on, the collector voltage is pulled low, the voltage at the inverting input terminal of the operational amplifier U1A is lower than the voltage at the non-inverting input terminal, the operational amplifier U1A outputs a high level, and this high level passes through the eighth diode D8 to the port PROTCET to start power amplifier protection.

[0044] The overcurrent detection circuit of the present application synchronously detects the voltage drops of the first field-effect transistor Q1 and the second field-effect transistor Q2 when the first output end HO and the second output end LO output high and low levels, so as to be able to achieve fast detection of overcurrent cycle by cycle. Moreover, the overcurrent detection circuit consumes less electric energy, has low detection loss and detection cost, and reduces the cost of overcurrent protection.

[0045] According to one aspect of the embodiments of the present application, a digital power amplifier device is provided, such as Figures 1 - 5As shown, the digital power amplifier device includes a digital power amplifier circuit, a power amplifier protection circuit, and an overcurrent detection circuit as described in the above embodiment. The overcurrent detection circuit is connected to the digital power amplifier circuit, and the output end of the overcurrent detection circuit is connected to the power amplifier protection circuit. The power amplifier protection circuit is used to trigger a power amplifier protection operation after receiving the power amplifier protection signal from the overcurrent detection circuit. Among them, the power amplifier protection circuit can be connected to at least one of the digital power amplifier circuit, the power supply of the digital power amplifier circuit, and the circuit for inputting an audio signal to the digital power amplifier circuit, and reduce the current in the digital power amplifier circuit or turn off the digital power amplifier circuit through the power amplifier protection circuit.

[0046] Optionally, as Figure 3 shown, the digital power amplifier circuit further includes a first inductor L1 and a first capacitor C1. The first end of the first inductor L1 is connected to the source electrode of the field effect transistor, the second end of the first inductor L1 is connected to the power amplifier output end and the first end of the first capacitor C1, and the second end of the first capacitor C1 is grounded. An LC filter circuit is formed by the first inductor L1 and the first capacitor C1.

[0047] The terms "first", "second", "third", "fourth", "1", "2", etc. (if any) in the specification, claims and above drawings of this application are used to distinguish similar objects and do not necessarily have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of this application described here can be implemented in an order other than the illustrated or textually described order.

[0048] It should be understood that although the flowchart of the embodiments of this application indicates each operation step by an arrow, the execution order of these steps is not limited to the order indicated by the arrow. Unless there is a clear description in this article, in some implementation scenarios of the embodiments of this application, the implementation steps in each flowchart can be executed in other orders according to requirements. In addition, some or all of the steps in each flowchart may include multiple sub-steps or multiple stages based on the actual implementation scenario. Some or all of these sub-steps or stages can be executed at the same time, and each sub-step or stage among these sub-steps or stages can also be executed at different times respectively. In the scenario where the execution times are different, the execution order of these sub-steps or stages can be flexibly configured according to requirements, and the embodiments of this application do not limit this.

[0049] The above are only optional implementation manners of some implementation scenarios of this application. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the technical concept of the solution of this application, adopting other similar implementation means based on the technical idea of this application also belongs to the protection scope of the embodiments of this application.

Claims

1. An overcurrent detection circuit, characterized in that: The overcurrent detection circuit is connected to the digital power amplifier circuit, the digital power amplifier circuit includes a pulse signal generating circuit and a field effect transistor that is turned on at a high level, the output end of the pulse signal generating circuit includes a first output end and a second output end, the first output end and the second output end have different time periods for outputting a high level in the same PWM cycle, the field effect transistor includes a first field effect transistor and a second field effect transistor, the gate of the first field effect transistor is connected to the first output end, the gate of the second field effect transistor is connected to the second output end, the source of the first field effect transistor and the drain of the second field effect transistor are connected to the overcurrent detection circuit and the power amplifier output end, and the drain of the first field effect transistor is connected to a positive power supply in a power supply, and the source of the second field effect transistor is connected to a negative power supply in the power supply; The overcurrent detection circuit includes an input end, a first detection end, and a second detection end. The input end is connected to the gate of the first field effect transistor and the gate of the second field effect transistor, the first detection end is connected to the drain of the first field effect transistor and the drain of the second field effect transistor, the second detection end is connected to the source of the first field effect transistor and the source of the second field effect transistor, and the first detection end is electrically connected to the input end. The overcurrent detection circuit is used to output a power amplifier protection signal when the first detection end and the second detection end detect that the current passing through the first field effect transistor and / or the second field effect transistor exceeds a preset value.

2. The overcurrent detection circuit according to claim 1, characterized in that: The overcurrent detection circuit also includes a first detection circuit, which includes a second resistor and a first transistor, wherein the first end of the second resistor is connected to the gate of the first field effect transistor and the emitter of the first transistor, and the second end of the second resistor is connected to the base of the first transistor and the source of the first field effect transistor.

3. The overcurrent detection circuit according to claim 2, characterized in that: The first detection circuit also includes a first diode, a first resistor, a second diode and a third diode, the anode of the first diode is connected to the second end of the first resistor, the anode of the second diode, the first end of the second resistor, and the anode of the third diode, the cathode of the first diode is connected to the drain of the first field effect transistor, the cathode of the third diode is connected to the first end of the first resistor and the gate of the first field effect transistor, and the cathode of the second diode is connected to the emitter of the first transistor.

4. The overcurrent detection circuit according to claim 2, characterized in that: The first detection circuit further includes a fourth diode and a fourth resistor. The anode of the fourth diode is connected to the collector of the first transistor, and the cathode of the fourth diode is connected to the first end of the fourth resistor.

5. The overcurrent detection circuit according to claim 1, characterized in that: The overcurrent detection circuit also includes a second detection circuit, which includes a fifth diode, a second transistor and an eighth resistor, the cathode of the fifth diode is connected to the output end of the power amplifier, the anode is connected to the base of the second transistor, the first end of the eighth resistor, and the gate of the second field effect transistor, and the emitter of the second transistor is connected to the second end of the eighth resistor and the source of the second field effect transistor.

6. The overcurrent detection circuit according to claim 5, characterized in that: The second detection circuit also includes: a sixth resistor, a seventh resistor, and an operational amplifier, the first end of the sixth resistor is connected to the collector of the second transistor, the second end of the sixth resistor is connected to the first end of the seventh resistor and the inverting input terminal of the operational amplifier, the second end of the seventh resistor is connected to a DC power supply, and the non-inverting input terminal of the operational amplifier is grounded.

7. The overcurrent detection circuit according to claim 5, characterized in that: The second detection circuit also includes a fifth resistor, a sixth diode and a seventh diode. The first end of the fifth resistor is connected to the gate of the second field effect transistor and the cathode of the sixth diode, the second end of the fifth resistor is connected to the anode of the sixth diode and the first end of the eighth resistor, the anode of the seventh diode is connected to the emitter of the second transistor, and the cathode of the seventh diode is connected to the second end of the eighth resistor.

8. A digital power amplifier device, characterized in that: The digital power amplifier device includes a digital power amplifier circuit, a power amplifier protection circuit and an overcurrent detection circuit as described in any one of claims 1 to 7, the overcurrent detection circuit is connected to the digital power amplifier circuit, and the output end of the overcurrent detection circuit is connected to the power amplifier protection circuit, and the power amplifier protection circuit is used to trigger a power amplifier protection operation after receiving a power amplifier protection signal from the overcurrent detection circuit.

9. The digital power amplifier device according to claim 8, characterized in that: The digital power amplifier circuit also includes a first inductor and a first capacitor, wherein the first end of the first inductor is connected to the source of the field effect transistor, the second end of the first inductor is connected to the power amplifier output end and the first end of the first capacitor, and the second end of the first capacitor is grounded.

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