A headphone insertion detection circuit

Abstract

The utility model provides an earphone insertion detection circuit, which belongs to the field of earphone circuits. The earphone insertion detection circuit of the utility model comprises a detection circuit and a signal amplification circuit, wherein the input end of the detection circuit is connected to the MIC pin of the earphone socket, the output end of the detection circuit is connected to the input end of the signal amplification circuit, and the output end of the signal amplification circuit is connected to the detection pin of the processor for outputting the amplified detection signal. The beneficial effect of the utility model is that the reliability and stability of earphone insertion detection are improved.

Description

Technical Field

[0001] The utility model relates to the field of earphone circuits, in particular to an earphone insertion detection circuit. Background Art

[0002] With the development of mobile smart terminals, there are also various solutions for detecting the insertion of headphones, including capacitive sensor solutions, optical detection solutions, reed detection solutions, etc.

[0003] Capacitive sensor solutions and optical detection solutions are rarely used in conventional solutions due to cost reasons. The reed detection solution has been widely used in traditional designs due to its simple implementation and relatively low cost.

[0004] The implementation principle of the reed detection scheme is as follows:

[0005] The headphone detection pin is the 5th pin detection pin of the headphone jack connector JP7000. The detection pin is named HP_DET_L. When the headphone is not inserted, HP_DET_L is connected to the 6th pin, and the 6th pin is grounded. At this time, HP_DET_L is at a low level. When the headphone is inserted, the reed between the 5th and 6th pins will pop open, and HP_DET_L will be pulled up to 1.8V by VCCA1V8_CODEC through R7019. At this time, HP_DET_L is at a high level. HP_DET_L can output two logic states of high and low levels according to the different states of the reed. The CPU uses this to determine whether the headphone is inserted. This method has high requirements for the quality of the headphone jack, and because the quality of the jack on the current market is uneven, especially because the gold-plated tin-plated process technology is not good enough, the reed will be oxidized under long-term friction, which will cause the 5th and 6th pins to always be open, and it is impossible to determine whether the headphone is connected. Utility Model Content

[0006] In order to solve the problems in the prior art, the utility model provides an earphone insertion detection circuit, which can avoid the failure of inaccurate earphone connection detection caused by long-term oxidation of the earphone seat reed, and improve the reliability and stability of earphone detection.

[0007] The utility model discloses an earphone insertion detection circuit, comprising a detection circuit and a signal amplifying circuit, wherein the input end of the detection circuit is connected to the MIC pin of the earphone socket, the output end of the detection circuit is connected to the input end of the signal amplifying circuit, and the output end of the signal amplifying circuit is connected to the detection pin of the processor for outputting the amplified detection signal.

[0008] Furthermore, it also includes a switch circuit, which is arranged between the output end of the signal amplifying circuit and the detection pin of the processor.

[0009] Furthermore, the switching circuit includes an NMOS tube Q59 and a resistor R611, wherein the gate of the NMOS tube Q59 is connected to the output end of the signal amplification circuit, the source is connected to the power ground, the drain is respectively connected to one end of the resistor R611 and the detection pin of the processor, and the other end of the resistor R611 is connected to the power supply.

[0010] Furthermore, the detection circuit includes an impedance matching unit and a filtering unit, wherein the input end of the impedance matching unit is connected to the MIC pin of the headphone socket, the output end is connected to the output end of the filtering unit, and the output end of the filtering unit is connected to the input end of the amplifying unit.

[0011] Furthermore, the impedance matching unit is an impedance matching resistor, and the filtering unit is one or more parallel-connected grounding capacitors.

[0012] Furthermore, the signal amplifying circuit comprises a signal detection processing unit and a signal amplifying unit connected in series, and an output end of the signal amplifying unit outputs an amplified detection signal.

[0013] Furthermore, the signal detection processing unit includes an operational amplifier U51A, a resistor R363, a resistor R379, a resistor R717, a resistor R603, and a resistor R604, wherein the non-phase input terminal of the operational amplifier U51A is respectively connected to one end of the resistor R363 and the resistor R379, the inverting input terminal of the operational amplifier U51A is respectively connected to one end of the resistor R717, the resistor R603, and the resistor R604, the other end of the resistor R379 is grounded, the other ends of the resistor R363 and the resistor R717 are respectively connected to the system power supply, the other end of the resistor R603 is connected to the output end of the detection circuit, and the other end of the resistor R604 is connected to the output end of the operational amplifier U51A.

[0014] Furthermore, the signal amplification unit includes an operational amplifier U51B, a resistor R606, and a resistor R605, wherein the non-inverting input terminal of the operational amplifier U51B is connected to the output terminal of the operational amplifier U51A, the inverting input terminal of the operational amplifier U51B is respectively connected to one end of the resistor R606 and the resistor R605, the other end of the resistor R605 is grounded, and the other end of the resistor R606 is connected to the output terminal of the operational amplifier U51B.

[0015] Compared with the prior art, the utility model has the following beneficial effects: the existing reed detection pin is cleverly abandoned, the physical detection method is avoided, and the MIC pin detection is used instead, and the small voltage difference of the MIC pin when the earphone is not connected and when the earphone is connected is used to detect whether the earphone is inserted, and the detected signal is amplified by the signal amplification circuit, so that the processor can detect it very conveniently;

[0016] By setting up a switch circuit, the analog signal is converted into high and low levels, which improves the reliability and stability of the solution;

[0017] In addition, the utility model adds a detection circuit, a signal amplifying circuit and a switch circuit on the basis of the traditional design, the circuit is simple, the modification is small and the cost is controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the solutions in the present invention or the prior art, a brief introduction will be given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 This is a circuit diagram of the utility model;

[0020] Figure 2 This is the principle diagram of the detection circuit in the utility model;

[0021] Figure 3 This is a circuit schematic diagram of an embodiment of a signal amplification circuit of the utility model;

[0022] Figure 4 This is a circuit schematic diagram of an embodiment of a switch circuit of the utility model. DETAILED DESCRIPTION

[0023] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by technicians in the technical field of the present invention; the terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of the present invention or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0024] Reference to "embodiments" in the present invention means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it mutually exclusive, independent, or alternative to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described in the present invention may be combined with other embodiments.

[0025] In order to enable those skilled in the art to better understand the solution of the utility model, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the accompanying drawings.

[0026] like Figure 1 As shown, the earphone insertion detection circuit of the utility model includes a detection circuit and a signal amplification circuit, wherein the input end of the detection circuit is connected to the MIC pin of the earphone socket, the output end of the detection circuit is connected to the input end of the signal amplification circuit, and the output end of the signal amplification circuit is connected to the detection pin of the processor for outputting the amplified detection signal.

[0027] The utility model takes into account the problem of inaccurate headphone connection detection caused by oxidation of the headphone reed after long-term use. Therefore, the existing reed detection pin is abandoned to avoid physical detection, and the MIC pin is used for detection. For conventional headphones, the MIC pin has a small voltage difference when the headphone is not connected and when it is connected, and the voltage difference is between 0.3V and 0.9V. The CPU main control can be designed to detect the MIC pin voltage difference to determine whether the headphone is inserted. However, since this voltage difference is uncertain, when the voltage difference is very small, there is a higher requirement for the resolution of the ADC. Therefore, the voltage difference can be amplified and the amplified value can be used for detection, thereby improving the reliability and stability of headphone detection.

[0028] Preferably, this example further includes a switch circuit, which is arranged between the output end of the signal amplifying circuit and the detection pin of the processor. By controlling the switch of the MOS tube with the detection signal value amplified by the signal amplifying circuit, the high and low levels of the output signal of the MOS tube are controlled. The CPU main control only needs to judge whether the earphone is connected according to the detected level state, and the implementation method is more stable and reliable.

[0029] like Figure 2 As shown, the detection circuit of this example includes an impedance matching unit and a filtering unit, wherein the input end of the impedance matching unit is connected to the MIC pin of the headphone socket, the output end is connected to the output end of the filtering unit, and the output end MIC_IN_DET of the filtering unit is connected to the input end of the amplifying unit.

[0030] The impedance matching unit in this example is an impedance matching resistor, and the filtering unit is one or more parallel grounded capacitors. Based on the traditional solution, a MIC_IN_DET circuit is added to the MIC pin, which is the DET signal that needs to be amplified. The newly added grounded capacitor C7017 plays a filtering role, reduces high-frequency noise, and avoids overshoot. The series resistor R7012 can achieve impedance matching and reduce signal reflection.

[0031] like Figure 3As shown, the signal amplifying circuit of this example includes a signal detection processing unit and a signal amplifying unit connected in series, and the output end of the signal amplifying unit outputs the amplified detection signal HOPNE_DET.

[0032] The signal detection processing unit in this example includes an operational amplifier U51A, a resistor R363, a resistor R379, a resistor R717, a resistor R603, and a resistor R604, wherein the non-inverting input terminal of the operational amplifier U51A is respectively connected to one end of the resistor R363 and the resistor R379, the inverting input terminal of the operational amplifier U51A is respectively connected to one end of the resistor R717, the resistor R603, and the resistor R604, the other end of the resistor R379 is grounded, the other ends of the resistor R363 and the resistor R717 are respectively connected to the system power supply, the other end of the resistor R603 is connected to the output end of the detection circuit, and the other end of the resistor R604 is connected to the output end of the operational amplifier U51A.

[0033] The signal amplification unit in this example includes an operational amplifier U51B, a resistor R606, and a resistor R605, wherein the non-inverting input terminal of the operational amplifier U51B is connected to the output terminal of the operational amplifier U51A, the inverting input terminal of the operational amplifier U51B is connected to one end of the resistor R606 and the resistor R605 respectively, the other end of the resistor R605 is grounded, and the other end of the resistor R606 is connected to the output terminal of the operational amplifier U51B.

[0034] In this example, the signal detection and processing unit calculates the difference through the operational amplifier U51A, and then amplifies the small voltage through U52B. Assuming that when the earphone is connected, the voltage difference changes to 0.3V. Then, the positive input terminal 3pin of the operational amplifier U51A in this example is divided into 2.5V by resistors R363 and R379. According to the virtual disconnection characteristics of the operational amplifier, the negative input terminal 2pin of the operational amplifier U51A is also 2.5V. When the earphone is not connected, MIC_IN_DET is disconnected from the earphone, and MIC_IN_DET is pulled up to 2.5V by R603. Then both ends of the input of operation U51A are VCC5V0_SYS. At this time, the output of the output 1pin of the operational amplifier U51A is 0V, so the output of the output 7pin of the operational amplifier U52B is also 0V; when the earphone is connected, the MIC_IN_DET pin is pulled down by 0.3V, and the level of the MIC_IN_DET pin is about 2.2V. After calculation, the output of the output 1pin of the operational amplifier U51A, namely Vo, is 0.3V. The operational amplifier U52B sets the amplification factor to 3 through resistors R605 and R606, so the output of the 7pin of U52B is about 0.9V. Of course, this example is just an example, and the operational amplifier U52B can also be set to other multiples according to the feedback values ​​of resistors R605 and R606.

[0035] In this example, a triode or other amplifier circuit can also be used to realize the detection signal amplification function, so that it can be better detected by the processor.

[0036] like Figure 4 As shown, the switch circuit of this example includes an NMOS tube Q59 and a resistor R611, wherein the gate of the NMOS tube Q59 is connected to the output end of the signal amplification circuit, the source is connected to the power ground, the drain is respectively connected to one end of the resistor R611 and the detection pin of the processor, and the other end of the resistor R611 is connected to the power supply.

[0037] In this example, HPONE_DET is the amplified detection signal, the minimum turn-on voltage of NMOS tube Q59 is 0.4V, and HP_DET_SEND is output to the CPU and other processors. From the signal amplification circuit, it can be seen that HPONE_DET has two states: 0V and 0.9V. When HPONE_DET is 0V, 0V<0.4V, NMOS tube Q59 is turned off, and HP_DET_SEND outputs a high level. When HPONE_DET is 0.9V, 0.9V>0.4V, NMOS tube Q59 is turned on, and HP_DET_SEND outputs a low level. The CPU can detect whether the headset is involved according to the high and low states of HP_DET_SEND.

[0038] The switching circuit of the present invention can also use PMOS tubes and other switching elements. The various components in each module of the present invention can be selected according to actual use requirements, and the operational amplifier in the signal amplification circuit can be configured and calculated according to actual conditions, and is not limited to the voltage difference and voltage value in the present invention.

[0039] The utility model has the following innovative features:

[0040] 1. The existing reed detection pin is cleverly abandoned to avoid physical detection. MIC pin detection is used instead to design the detection circuit of the utility model;

[0041] 2. The utility model converts analog signals into high and low levels by setting a switch circuit, thereby improving the reliability and stability of the scheme;

[0042] 3. The utility model adds a detection circuit, a signal amplification circuit and a switch circuit on the basis of the traditional design, the circuit is simple, the modification is small and the cost is controllable.

[0043] The specific implementation methods described above are preferred implementation methods of the present utility model, and are not intended to limit the specific implementation scope of the present utility model. The scope of the present utility model includes but is not limited to the specific implementation methods. All equivalent changes made in accordance with the present utility model are within the protection scope of the present utility model.

Claims

1. A headphone insertion detection circuit, characterized in that: It includes a detection circuit and a signal amplification circuit, wherein the input end of the detection circuit is connected to the MIC pin of the headphone socket, the output end of the detection circuit is connected to the input end of the signal amplification circuit, and the output end of the signal amplification circuit is connected to the detection pin of the processor for outputting the amplified detection signal.

2. The headphone insertion detection circuit according to claim 1, characterized in that: It also includes a switch circuit, which is arranged between the output end of the signal amplifying circuit and the detection pin of the processor.

3. The earphone insertion detection circuit according to claim 2, characterized in that: The switch circuit includes an NMOS tube Q59 and a resistor R611, wherein the gate of the NMOS tube Q59 is connected to the output end of the signal amplification circuit, the source is connected to the power ground, the drain is respectively connected to one end of the resistor R611 and the detection pin of the processor, and the other end of the resistor R611 is connected to the power supply.

4. The headphone insertion detection circuit according to any one of claims 1 to 3, characterized in that: The detection circuit includes an impedance matching unit and a filtering unit, wherein the input end of the impedance matching unit is connected to the MIC pin of the headphone socket, the output end is connected to the output end of the filtering unit, and the output end of the filtering unit is connected to the input end of the signal amplification circuit.

5. The earphone insertion detection circuit according to claim 4, characterized in that: The impedance matching unit is an impedance matching resistor, and the filtering unit is one or more parallel-connected grounding capacitors.

6. The earphone insertion detection circuit according to any one of claims 1 to 3, characterized in that: The signal amplifying circuit comprises a signal detection processing unit and a signal amplifying unit connected in series, and an output end of the signal amplifying unit outputs an amplified detection signal.

7. The earphone insertion detection circuit according to claim 6, characterized in that: The signal detection processing unit includes an operational amplifier U51A, a resistor R363, a resistor R379, a resistor R717, a resistor R603, and a resistor R604, wherein the non-inverting input terminal of the operational amplifier U51A is respectively connected to one end of the resistor R363 and the resistor R379, the inverting input terminal of the operational amplifier U51A is respectively connected to one end of the resistor R717, the resistor R603, and the resistor R604, the other end of the resistor R379 is grounded, the other ends of the resistor R363 and the resistor R717 are respectively connected to the system power supply, the other end of the resistor R603 is connected to the output end of the detection circuit, and the other end of the resistor R604 is connected to the output end of the operational amplifier U51A.

8. The earphone insertion detection circuit according to claim 7, characterized in that: The signal amplification unit includes an operational amplifier U51B, a resistor R606, and a resistor R605, wherein the non-inverting input terminal of the operational amplifier U51B is connected to the output terminal of the operational amplifier U51A, the inverting input terminal of the operational amplifier U51B is connected to one end of the resistor R606 and the resistor R605 respectively, the other end of the resistor R605 is grounded, and the other end of the resistor R606 is connected to the output terminal of the operational amplifier U51B.

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