An MCU port protection circuit

Abstract

The embodiment of the present application belongs to the field of circuit design, and relates to an MCU port protection circuit, which includes a signal input module, a signal transmission module, a protection module, and a signal output module; the signal input module is used to receive signals; the signal transmission module is connected between the signal input module and the signal output module, and is used to transmit the signal from the signal input module to the signal output module when the voltage of the signal is a normal signal voltage; the protection module includes a first protection unit and a second protection unit, and is connected to the signal transmission module, and the protection module is used to trigger the protection circuit to enter a protection state when the signal voltage of the signal is an abnormal signal voltage; the signal output module is used to output the signal. The technical solution provided by the present application can prevent abnormal signal voltages from entering the interior of electronic products through the MCU port, prevent damage to electronic products, and at the same time, can also play a role in suppressing the influx of static electricity.

Description

Technical Field

[0001] This application relates to the technical field of circuit design, and more specifically, to an MCU port protection circuit. Background Art

[0002] With the popularization of electronic products, many electronic products are equipped with external interfaces, buttons and other product interaction parts. During the use of electronic products, when there is a signal line connection between the MCU (Microcontroller Unit) port inside the product system and the external interface or button, static electricity enters the product system through the parts frequently contacted by the human body such as the external interface and button, causing product damage.

[0003] In the related art, by placing an electrostatic suppression ESD (Electro-Static discharge) device on the signal line near the external interface or button, the ESD device has a good suppression effect on the instantaneous surge voltage and can play a certain protective role for the product. However, during use, due to wiring and other reasons, when an abnormal voltage enters the electronic product system through the external interface for a long time, the function of the ESD device will fail. Summary of the Invention

[0004] The technical problem to be solved by the embodiments of this application is that there is a signal line connection between the MCU port inside the electronic product and the external interface, and due to wiring and other reasons, an abnormal voltage enters the system through the external interface, thereby damaging the product.

[0005] To solve the above technical problem, the embodiments of this application provide an MCU port protection circuit, and adopt the following technical solutions:

[0006] A signal input module, a signal transmission module, a protection module, and a signal output module;

[0007] The signal input module is used to receive signals;

[0008] The signal transmission module is connected between the signal input module and the signal output module, and is used to transmit the signal from the signal input module to the signal output module when the voltage of the signal is a normal signal voltage;

[0009] The protection module includes a first protection unit and a second protection unit, and is connected to the signal transmission module. The protection module is used to trigger the protection circuit to enter a protection state when the voltage of the signal is an abnormal signal voltage; wherein, the first protection unit is used to turn on the protection state when the abnormal signal voltage is less than a first preset threshold; the second protection unit is used to turn on the protection state when the abnormal signal voltage is greater than a second preset threshold;

[0010] The signal output module is used to output the signal.

[0011] Further, the first protection unit includes a first resistor, a second resistor, and a first triode;

[0012] One end of the first resistor is connected to the signal input module, and the other end is respectively connected to one end of the second resistor and the base of the first triode;

[0013] The base of the first triode is connected to the other end of the first resistor, the collector of the first triode is connected to the signal output module, and the emitter of the first triode is grounded;

[0014] One end of the second resistor is connected to the other end of the first resistor, the other end of the second resistor is grounded, and is connected in parallel with the BE pole of the first triode.

[0015] Further, the first triode is specifically a PNP type triode.

[0016] Further, the first protection unit further includes a first diode, the positive pole of the first diode is connected to the base of the first triode, and the negative pole of the first diode is respectively connected to the other end of the first resistor and one end of the second resistor.

[0017] Further, the second protection unit includes a zener diode, a third resistor, a fourth resistor, and a second triode;

[0018] The negative pole of the zener diode is connected to the signal input module, and the positive pole of the zener diode is connected to one end of the third resistor;

[0019] One end of the third resistor is connected to the positive pole of the zener diode, and the other end of the third resistor is respectively connected to the base of the second triode and one end of the fourth resistor;

[0020] The base of the second triode is connected to the other end of the third resistor, the collector of the second triode is connected to the signal output module, and the emitter of the second triode is grounded;

[0021] One end of the fourth resistor is connected to the other end of the third resistor, the other end of the fourth resistor is grounded, and is connected in parallel with the BE pole of the second triode.

[0022] Further, the second triode is specifically an NPN type triode.

[0023] Further, the second protection unit further includes a second diode. The positive electrode of the second diode is respectively connected to the other end of the third resistor and one end of the fourth resistor, and the negative electrode of the second diode is connected to the base of the second triode.

[0024] Further, the signal transmission module includes a fifth resistor, which connects the signal input module and the signal output module.

[0025] Further, the signal transmission module further includes a filtering unit, which is connected to the fifth resistor and is used to suppress the spike pulses in the signal.

[0026] Further, the filtering unit includes a filtering resistor and a capacitor;

[0027] One end of the filtering resistor is connected to the signal input module, the other end of the filtering resistor is respectively connected to one end of the fifth resistor and one end of the capacitor, and the other end of the capacitor is grounded.

[0028] Compared with the prior art, the embodiments of the present application mainly have the following beneficial effects:

[0029] The present application provides an MCU port protection circuit. When the voltage of the signal input by the signal input module is an abnormal signal voltage, the protection module triggers the protection circuit to enter the protection state, so that the signal cannot be output through the signal output module. In this way, the signal input module and the signal output module can be isolated, and further, it can be avoided that the abnormal signal voltage enters the internal part of the electronic product through the MCU port, preventing damage to the electronic product. At the same time, it can also play a role in suppressing the influx of static electricity. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the solutions in the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained according to these drawings without creative efforts.

[0031] Figure 1 Schematic structural diagram of the MCU port protection circuit provided by the embodiments of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this application belongs; the terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above drawings are intended to cover non-exclusive inclusion. The terms "first", "second", etc. in the specification and claims of this application or the above drawings are used to distinguish different objects and not to describe a specific order.

[0033] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in connection with the embodiments can be included in at least one embodiment of this application. The phrase does not necessarily refer to the same embodiment at every occurrence in the specification, nor is it an independent or alternative embodiment mutually exclusive of other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0034] In order to enable those skilled in the technical field to better understand the solution of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the drawings.

[0035] In order to solve the problem that in the related art, there is a signal line connection between the internal MCU port of an electronic product and an external interface, and due to reasons such as wiring, an abnormal voltage enters the system through the external interface, thereby damaging the product, the embodiments of this application provide an MCU port protection circuit. For the specific structural schematic diagram, see Figure 1 as shown, including: a signal input module 1, a signal transmission module 2, a protection module, and a signal output module 4.

[0036] The signal input module 1 is used to receive signals. There is a signal line connection between the internal MCU port of the electronic product system and an external interface or a button, and the signal can be input to the MCU port through the external interface or the button. For specific reference, see Figure 1 as shown, the signal input module 1 is SIGNAL_INPUT.

[0037] The signal transmission module 2 is connected between the signal input module 1 and the signal output module 4, and transmits the signal from the signal input module 1 to the signal output module 4, so as to input it into the electronic product.

[0038] It should be noted that the signal transmission module 2 only transmits the signal when the voltage of the input signal is a normal signal voltage, and this signal is used for the communication of the electronic product. Whether the input voltage is a normal value is determined according to the circuit designed according to actual needs.

[0039] The protection module is connected to the signal transmission module 2. The protection module is used to trigger the protection circuit to enter the protection state when the voltage of the signal is an abnormal signal voltage, and the signal cannot be transmitted through the signal transmission module 2, thereby isolating the signal input module 1 and the signal output module 4.

[0040] In this embodiment, the abnormal signal voltage is any one of less than the first preset threshold or greater than the first preset threshold. Specifically, the parameters of the MCU port protection circuit in this embodiment are suitable for 3.3V signal voltage communication. When the signal voltage is less than -1.2V or greater than 4.5V, it is recognized as an abnormal signal voltage by the protection circuit. At this time, the protection function of the protection circuit is activated, so that the amplitude of the signal reaching the GPIO (General Purpose I / O Port) of the electronic product chip rapidly decays to about 0V, playing a protective role.

[0041] In this embodiment, the protection module includes a first protection unit 31 and a second protection unit 32. When the abnormal signal voltage is less than the first preset threshold, the first protection unit 31 is turned on, and the protection circuit enters the protection state; when the abnormal signal voltage is greater than the second preset threshold, the second protection unit 32 is turned on, and the protection circuit enters the protection state.

[0042] Specifically, the first protection unit 31 includes a first resistor R101, a second resistor R105, and a first triode D102. The first resistor R101, the second resistor R105, and the first triode D102 are electrically connected. One end of the first resistor R100 is connected to the signal input module 1, and the other end of the first resistor R101 is respectively connected to one end of the second resistor R105 and the base B of the first triode D102.

[0043] The base B of the first triode D102 is connected to the other end of the first resistor R101. The collector C of the first triode D102 is connected to the signal output module 4, and the emitter E of the first triode is grounded.

[0044] One end of the second resistor R105 is connected to the other end of the first resistor R101. The other end of the second resistor R105 is grounded and forms a parallel connection with the BE pole of the first triode D102.

[0045] In this embodiment, the functions of the first resistor R101 and the second resistor R105 are both voltage division.

[0046] In this embodiment, the first triode D102 is specifically a PNP type triode. The current flow direction of the PNP type triode is from the emitter E to the base B and from the emitter E to the collector C. When the voltage between the BE poles of the first triode D102 is greater than 0.7V, the first triode D102 is in the conduction state.

[0047] In this embodiment, the first protection unit 31 further includes a first diode D105. The positive electrode of the first diode D105 is connected to the base B of the first triode D102, and the negative electrode of the first diode D105 is respectively connected to the other end of the first resistor R101 and one end of the second resistor R105.

[0048] It should be noted that the first diode D105 is used to protect the first triode D102. When a relatively large positive abnormal signal voltage is input, the voltage cannot pass through the first diode D105, and the first diode D105 is in an open state, thereby isolating it from the BE electrode of the first triode D102 to avoid damage to the first triode D102.

[0049] As a specific implementation manner, the first protection unit 31 includes a first resistor R101, a second resistor R105, a first diode D105, and a first triode D102. When the signal voltage is less than the first preset threshold, for example, when the signal voltage is less than -1.2V, the signal forms a path through the EB electrode of the first triode D102, the first diode D105, and the first resistor R101. At this time, both the emitter E and the collector C of the first triode D102 are forward-biased, reaching the saturation conduction state, and the CE electrode is in a linearly connected state. The voltage of the signal output module SIGNAL_OUTPUT is close to the ground level, and the signal cannot be output through SIGNAL_OUTPUT, playing a protective role.

[0050] In this embodiment, the second protection unit 32 includes a zener diode D100, a third resistor R103, a fourth resistor R104, and a second triode D101, and the zener diode D100, the third resistor R103, the fourth resistor R104, and the second triode D101 are electrically connected.

[0051] The negative electrode of the zener diode D100 is connected to the signal input module 1, and the positive electrode of the zener diode D100 is connected to one end of the third resistor R103.

[0052] It should be noted that the zener diode needs to reach a certain voltage value to conduct, which can avoid mis-triggering the protection circuit under normal voltage signals. In addition, it also has the function of maintaining voltage stability.

[0053] One end of the third resistor R103 is connected to the positive electrode of the zener diode D100, and the other end of the third resistor R103 is respectively connected to the base B of the second triode D101 and one end of the fourth resistor R104;

[0054] The collector C of the second triode D101 is connected to the signal output module 4, and the emitter E of the second triode D101 is grounded and forms a parallel connection with the BE electrode of the second triode D101.

[0055] In this embodiment, the functions of the third resistor R103 and the fourth resistor R104 are voltage division.

[0056] In this embodiment, the second triode D101 is specifically an NPN-type triode. In an NPN-type triode, there are two current flow directions. One is the base current flowing from the base B to the emitter E, and the other is the collector current flowing from the collector C to the emitter E. When the voltage between the BE electrodes of the second triode D101 is greater than 0.7V, the second triode D101 is in the conducting state.

[0057] In this embodiment, the second protection unit 32 further includes a second diode D106. The positive electrode of the second diode D106 is respectively connected to the other end of the third resistor R103 and one end of the fourth resistor R104, and the negative electrode of the second diode D106 is connected to the base B of the second triode D101.

[0058] It should be noted that the second diode D106 is used to protect the second triode D101. When a negative abnormal signal voltage with a large amplitude is input, the voltage cannot pass through the second diode D106, and the second diode D106 is in the off state, thereby isolating it from the BE electrodes of the second triode D101 to avoid damage to the second triode D101.

[0059] As a specific implementation manner, the second protection unit 32 includes a zener diode D100, a third resistor R103, a fourth resistor R104, a second diode D106, and a second triode D101. When the signal voltage is greater than the second preset threshold, for example, when the signal voltage is greater than 4.5V, the signal forms a path through the zener diode D100, the third resistor R103, the second diode D106, and the BE electrodes of the second triode D101. At this time, both the emitter E and the collector C of the second triode D101 are forward-biased, reaching the saturation conduction state, and the CE electrodes are in a linearly connected state. The voltage of the signal output module SIGNAL_OUTPUT is close to the ground level, and the signal cannot be output through SIGNAL_OUTPUT, playing a protective role.

[0060] In this embodiment, the signal transmission module 2 includes a fifth resistor R102, and the fifth resistor R102 connects the signal input module 1 and the signal output module 4. When the voltage of the signal received by the signal transmission module 2 is a normal signal voltage, the signal is transmitted to the signal output module 4 through the fifth resistor R102.

[0061] It should be noted that the fifth resistor R102 can also isolate the input and output of the signal, and at the same time, when the first triode D101 and the second triode D102 are saturated and conducting, it bears the voltage drop of most of the abnormal signal voltage.

[0062] In some alternative implementation manners of this embodiment, the signal transmission module 2 further includes a filtering unit. The filtering unit is connected to the fifth resistor R102 and is used to suppress the spike pulses in the signal and maintain the stability of the circuit operation.

[0063] Specifically, the filtering unit includes a filtering resistor R100 and a capacitor C100. One end of the filtering resistor R100 is connected to the signal input module 1, the other end of the filtering resistor R100 is connected to one end of the fifth resistor R102, one end of the capacitor C100 is connected to the other end of the filtering resistor R100, and the other end of the capacitor C100 is grounded.

[0064] The first resistor R100 and the capacitor C100 form a first - order RC filtering network to perform primary suppression on the spike pulses in the signal, avoiding mis - triggering of the protection circuit and affecting the normal communication of the signal.

[0065] It should be understood that the high - order harmonic components of the spike pulses are rich, appear frequently, and have a high amplitude. They are a main interference noise polluting the low - voltage 220V power - frequency power grid and bring many adverse effects to the AC - powered electronic system. Therefore, suppression is required.

[0066] In this embodiment, the signal output module 4 is used to output the signal. Specifically, see Figure 1 As shown, the signal output module is SIGNAL_OUTPUT. When the voltage of SIGNAL_OUTPUT is close to the low level, it can play a protection role.

[0067] It should be noted that when an abnormal signal voltage is input to the protection circuit, the protection circuit activates the protection function, making the voltage of the signal output module SIGNAL_OUTPUT close to the level and the signal unable to be output. The abnormal signal can be isolated. Similarly, for abnormal signals such as static electricity, it can also play an isolation role to prevent static electricity from entering the product interior.

[0068] As a specific implementation manner, the MCU port protection circuit includes a signal input module SIGNAL_INPUT, a filtering resistor R100, a capacitor C100, a first resistor R101, a second resistor R105, a first diode D105, a first triode D102, a zener diode D100, a third resistor R103, a fourth resistor R104, a second diode D106, a second triode D101, a fifth resistor R102, and a signal output module SIGNAL_OUTPUT.

[0069] When the voltage of the signal received by the signal input module 1 is a normal signal voltage, the signal forms a path through the filtering resistor R100 and the fifth resistor R102 and is transmitted to the signal output module 4.

[0070] When the voltage of the signal received by the signal input module 1 is an abnormal signal voltage and the abnormal signal voltage is less than the first preset threshold, the signal forms a path through the EB pole of the first triode D102, the first diode D105, the first resistor R101, and the filter resistor R100. The voltage of the signal output module SIGNAL_OUTPUT is close to the ground level, and the signal cannot be output through SIGNAL_OUTPUT, thus playing a protective role.

[0071] When the voltage of the signal received by the signal input module 1 is an abnormal signal voltage and the abnormal signal voltage is greater than the second preset threshold, the signal forms a path through the filter resistor R100, the voltage stabilizing diode D100, the third resistor R103, the second diode D106, and the BE pole of the second triode D101. The voltage of the signal output module SIGNAL_OUTPUT is close to the ground level, and the signal cannot be output through SIGNAL_OUTPUT, thus playing a protective role.

[0072] The MCU port protection circuit provided by this application triggers the protection circuit to enter the protection state when the voltage of the signal input by the signal input module is an abnormal signal voltage through the protection module, so that the signal cannot be output through the signal output module. In this way, the signal input module and the signal output module can be isolated, and further, the abnormal signal voltage can be prevented from entering the internal part of the electronic product through the MCU port to prevent damage to the electronic product. At the same time, it can also play a role in suppressing the influx of static electricity.

[0073] Obviously, the embodiments described above are only a part of the embodiments of this application, rather than all of them. The drawings give the preferred embodiments of this application, but do not limit the patent scope of this application. This application can be implemented in many different forms. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosed content of this application more thorough and comprehensive. Although this application has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions recorded in the foregoing specific embodiments, or perform equivalent replacements for some of the technical features. Any equivalent structure directly or indirectly using the content of the specification and drawings of this application in other related technical fields is equally within the scope of the patent protection of this application.

Claims

1. An MCU port protection circuit, characterized in that, It includes: a signal input module, a signal transmission module, a protection module, and a signal output module; The signal input module is used to receive signals; The signal transmission module is connected between the signal input module and the signal output module, and is used to transmit the signal from the signal input module to the signal output module when the voltage of the signal is a normal signal voltage; The protection module includes a first protection unit and a second protection unit, and is connected to the signal transmission module. The protection module is used to trigger the protection circuit to enter the protection state when the voltage of the signal is an abnormal signal voltage; wherein, the first protection unit is used to turn on the protection state when the abnormal signal voltage is less than a first preset threshold; the second protection unit is used to turn on the protection state when the abnormal signal voltage is greater than a second preset threshold; The signal output module is used to output the signal; Among them, the first protection unit includes a first resistor, a second resistor, and a first triode; One end of the first resistor is connected to the signal input module, and the other end is respectively connected to one end of the second resistor and the base of the first triode; The base of the first triode is connected to the other end of the first resistor, the collector of the first triode is connected to the signal output module, and the emitter of the first triode is grounded; One end of the second resistor is connected to the other end of the first resistor, the other end of the second resistor is grounded, and is connected in parallel with the BE pole of the first triode.

2. The MCU port protection circuit according to claim 1, wherein The first triode is specifically a PNP type triode.

3. The MCU port protection circuit according to claim 1, wherein The first protection unit further includes a first diode, the positive electrode of the first diode is connected to the base of the first triode, and the negative electrode of the first diode is respectively connected to the other end of the first resistor and one end of the second resistor.

4. The MCU port protection circuit according to claim 1, wherein, The second protection unit includes a zener diode, a third resistor, a fourth resistor, and a second triode; The negative electrode of the zener diode is connected to the signal input module, and the positive electrode of the zener diode is connected to one end of the third resistor; One end of the third resistor is connected to the positive electrode of the zener diode, and the other end of the third resistor is respectively connected to the base of the second triode and one end of the fourth resistor; The base of the second triode is connected to the other end of the third resistor, the collector of the second triode is connected to the signal output module, and the emitter of the second triode is grounded; One end of the fourth resistor is connected to the other end of the third resistor, the other end of the fourth resistor is grounded, and is connected in parallel with the BE pole of the second triode.

5. The MCU port protection circuit according to claim 4, wherein, The second triode is specifically an NPN type triode.

6. The MCU port protection circuit according to claim 4, wherein The second protection unit further includes a second diode, the positive electrode of the second diode is respectively connected to the other end of the third resistor and one end of the fourth resistor, and the negative electrode of the second diode is connected to the base of the second triode.

7. The MCU port protection circuit according to any one of claims 1-6, characterized in that, The signal transmission module includes a fifth resistor, connecting the signal input module and the signal output module.

8. The MCU port protection circuit according to claim 7, wherein The signal transmission module further includes a filtering unit, connected to the fifth resistor, for suppressing spike pulses in the signal.

9. The MCU port protection circuit according to claim 8, wherein The filtering unit includes a filtering resistor and a capacitor; One end of the filtering resistor is connected to the signal input module, the other end of the filtering resistor is respectively connected to one end of the fifth resistor and one end of the capacitor, and the other end of the capacitor is grounded.

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