Input protection circuit, circuit board and input protection method

Abstract

The invention discloses an input protection circuit, a circuit board and an input protection method, and relates to the technical field of electronic circuits. The input protection circuit is provided with a voltage input end and a voltage output end. The input protection circuit comprises a monitoring module and a protection module. A power supply branch is formed from the voltage input end to the voltage output end through the monitoring module and the protection module connected with the monitoring module; a first control port of the monitoring module is connected with a first receiving port of the protection module to form a first protection branch; a second control port of the monitoring module is connected with a second receiving port of the protection module to form a second protection branch; and a third control port of the monitoring module is connected with a third receiving port of the protection module to form a third protection branch. The input end is effectively protected, and the transient voltage suppression diode is prevented from being damaged by voltage overshoot; and board burning caused by large current due to capacitor short circuit is avoided.

Description

Technical Field

[0001] The present application relates to the technical field of electronic circuits, and in particular to an input protection circuit, a circuit board and an input protection method. Background Art

[0002] For circuit boards that require an external DC power supply, a transient voltage suppressor (TVS) is usually used at the power input to protect the voltage input and suppress overshoot, and an electronic fuse (EFUSE) is used to protect the back-end circuit. However, this method has certain limitations. Once the overshoot exceeds the maximum clamping voltage of the transient voltage suppressor diode, it will not be recoverable. The transient voltage suppressor diode will show a low resistance state, causing the EFUSE input to short-circuit to the ground, which can seriously burn the circuit board. In addition, a Schottky diode is designed at the output to protect the electronic fuse.

[0003] Typically, transient voltage suppression diodes and Schottky diodes are large in size, often in 7.11×6.22 packages, and take up more space on the circuit board layout. When the circuit board space is tight, it is difficult to set up both diodes at the same time, which weakens the circuit protection effect. In addition, the capacitor between the output end of the external power supply and the electronic fuse is not protected. If the capacitor is damaged by collision and short-circuited, there is a risk of burning the board. Summary of the invention

[0004] In order to implement high reliability protection for the external power input terminal, the present application provides the following technical solutions: In a first aspect, an input protection circuit is provided. The input protection circuit has a voltage input terminal and a voltage output terminal. The input protection circuit includes: a monitoring module and a protection module; From the voltage input end, through the monitoring module and the protection module connected to the monitoring module to the voltage output end, a power supply branch is formed; There are also: The first protection branch is used to protect the voltage output terminal; The second protection branch is used to enable or disconnect the external power supply module; The third protection branch is used to implement surge protection for the voltage input terminal.

[0005] Further, the monitoring module has: a first monitoring port, a second monitoring port, a first control port, a second control port and a third control port; The protection module has: a first receiving port, a second receiving port, a third receiving port, a first output port, a second output port, a third output port and a fourth output port; The first monitoring port is connected to the fourth output port as a voltage input terminal, the second monitoring port is connected to the first output port, the second output port is used as a voltage output terminal, the first control port is connected to the first receiving port to form a first protection branch, the second control port is connected to the second receiving port to form a second protection branch, and the third control port is connected to the third receiving port to form a third protection branch; The third output port is used to provide an enable signal to the external power supply module to enable or disconnect the external power supply module.

[0006] Further, the monitoring module includes: a detection unit, a trigger unit and a first resistor; The detection unit has: a first detection port, a second detection port, a third detection port and a status signal sending port; The trigger unit has: a first signal port, a second signal port, a third signal port and a status signal receiving port; The first detection port is connected to the second detection port and one end of the first resistor as a first monitoring port, the third detection port is connected to the other end of the first resistor as a second monitoring port, the status signal sending port is connected to the status signal receiving port, the first signal port is used as a first control port, the second signal port is used as a second control port, and the third signal port is used as a third control port.

[0007] Furthermore, the detection unit comprises: An analog-to-digital converter, a first voltage register, a first current register, a first selection switch and a first signal interface; The analog-to-digital converter has: a first voltage acquisition port, a first current acquisition port and a second current acquisition port; The first voltage acquisition port is used as the first detection port, the first current acquisition port is used as the second detection port, and the second current acquisition port is used as the third detection port; The first signal transmission port in the first signal interface serves as a status signal sending port; The analog-to-digital converter is connected to the first voltage register and the first current register respectively through the first selection switch, and is used to send the acquired voltage signal to the first voltage register and send the acquired current signal to the first current register.

[0008] Furthermore, the trigger unit includes: A digital-to-analog converter, a second voltage register, a second current register, a second selection switch, a second signal interface, a first comparator, a second comparator, and a NOR gate; The digital-to-analog converter has: a first voltage output port and a second voltage output port; The NOR gate has: a first logic input port, a second logic input port and a logic output port; The second signal transmission port in the second signal interface serves as a status signal receiving port; The first voltage output port is connected to the non-inverting input port of the first comparator, the inverting input port of the first comparator is connected to the first reference voltage, and the output port of the first comparator is used as the third signal port. The second voltage output port is connected to the non-inverting input port of the second comparator, the inverting input port of the second comparator is connected to the second reference voltage, and the output port of the second comparator is used as the second signal port. The output port of the first comparator is also connected to the first logic input port, the output port of the second comparator is also connected to the second logic input port, and the logic output port serves as a first signal port.

[0009] Furthermore, the first resistor is a precision resistor.

[0010] Further, the protection module includes: an output protection unit, a power protection unit and a surge protection unit; The output protection unit has: a first output protection port, a second output protection port and a third output protection port; The power protection unit has: a first power protection port and a second power protection port; The surge protection unit has: a first surge protection port and a second surge protection port; The first output protection port serves as the first receiving port, the second output protection port serves as the first output port, the third output protection port serves as the second output port, the first power supply protection port serves as the second receiving port, the second power supply protection port serves as the third output port, the first surge protection port serves as the third receiving port, and the second power supply protection port serves as the fourth output port.

[0011] Further, the output protection unit includes a first switching device; The first switch device has: a first switch device first pole, a first switch device second pole and a first switch device third pole; The first pole of the first switch device serves as the first output protection port, the second pole of the first switch device serves as the second output protection port, and the third pole of the first switch device serves as the third output protection port.

[0012] Further, the power protection unit includes a second switch device; The second switch device has: a second switch device first electrode, a second switch device second electrode; The first pole of the second switch device serves as a first power protection port, and the second pole of the second switch device serves as a second power protection port.

[0013] Further, the surge protection unit includes a third switch device and a first diode; The third switch device comprises: a third switch device first electrode and a third switch device second electrode; The first electrode of the third switch device serves as a first surge protection port, the second electrode of the third switch device is connected to the anode of the first diode, and the cathode of the first diode serves as a second power protection port.

[0014] Further, the circuit also includes a second diode; The cathode of the second diode is connected to the voltage output terminal, and the anode of the second diode is grounded.

[0015] Further, the circuit also includes at least one capacitor; One end of any one of the at least one capacitor is connected to the second monitoring port, and the other end of any one of the at least one capacitor is grounded.

[0016] The input protection circuit also includes: an external power supply module; The external power supply module has: a power supply output port and a power supply enable port; The power supply output port is connected to the voltage input port, and the power supply enable port is connected to the third output port.

[0017] Further, the external power supply module includes: a second resistor; One end of the second resistor serves as a power supply enable port, and the other end of the second resistor is connected to a working voltage, so that when the external power supply module works normally, the power supply enable port is at a low level.

[0018] In a second aspect, a circuit board is provided, the circuit board comprising the input protection circuit described in the first aspect; The circuit board has a first surface and a second surface arranged opposite to each other; A first switching device is disposed on the first surface of the circuit board, and a second diode is disposed on the second surface of the circuit board; The pin of the cathode of the second diode is electrically connected to the pin of the third electrode of the first switch device through the same through hole.

[0019] In a third aspect, an input protection method is provided, which is applied to the input protection circuit described in the first aspect, comprising: Connect the power supply output port of the external power supply module to the voltage input terminal; The current flowing through the power supply branch and the voltage at the voltage input terminal are obtained through the monitoring module; Determine whether the current flowing through the power supply branch exceeds the current threshold, and determine whether the voltage at the voltage input terminal exceeds the voltage threshold; In response to the current flowing through the power supply branch not exceeding the current threshold and the voltage at the voltage input terminal not exceeding the voltage threshold, the monitoring module transmits a first control signal to the first receiving port to control the first switching device to turn on, transmits a second control signal to the second receiving port to control the second switching device to turn on, and transmits a third control signal to the third receiving port to control the third switching device to turn on.

[0020] Furthermore, the circuit input protection method further includes: In response to the current flowing through the power supply branch exceeding the current threshold, the monitoring module transmits a second control signal to the second receiving port, and disconnects the power supply from the external power supply module to the voltage input terminal by turning off the second switch device.

[0021] Furthermore, the circuit input protection method further includes: In response to the voltage at the voltage input terminal exceeding the voltage threshold, the monitoring module transmits a third control signal to the third receiving port to protect the first diode by turning off the third switching device; and transmits a first control signal to the first receiving port to disconnect the power supply branch by turning off the first switching device.

[0022] The beneficial effects brought about by the technical solution provided by the embodiments of the present application are: by implementing an input protection circuit, a circuit board and an input protection method disclosed in the embodiments of the present application, through the coordinated use of a monitoring module and a protection module, when the current of the power supply branch exceeds the current threshold, the power supply of the external power supply module to the voltage input terminal is disconnected; when the voltage at the voltage input terminal exceeds the voltage threshold, the external power supply module is turned off, and the power supply branch is turned off, thereby effectively protecting the input terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 is a schematic diagram of an input protection circuit module provided in an embodiment of the present application; Figure 2 is a schematic diagram of a monitoring module provided in an embodiment of the present application; Figure 3 is a schematic diagram of a detection unit provided in an embodiment of the present application; Figure 4 is a schematic diagram of a trigger unit provided in an embodiment of the present application; Figure 5 is a schematic diagram of a protection module provided in an embodiment of the present application; Figure 6is another input protection circuit schematic provided in an embodiment of the present application; Figure 7 It is a schematic diagram of an input protection circuit including an external power supply module provided in an embodiment of the present application; Figure 8 It is a partial schematic diagram of the circuit board connection provided in the embodiment of the present application; Fig. 9 It is a schematic diagram of a circuit input protection method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in the implementation mode of this application will be clearly and completely described below in conjunction with the drawings in the implementation mode of this application. Obviously, the described implementation mode is only a part of the embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0026] Unless otherwise defined, the technical terms or scientific terms used in the present disclosure shall have the usual meanings understood by persons with ordinary skills in the field to which the present disclosure belongs. The words "first", "second" and similar words used in the present disclosure do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one", "one" or "the" do not indicate a quantity limitation, but indicate that there is at least one. The numbers in the drawings of the specification only indicate the distinction between various functional components or modules, and do not indicate the logical relationship between components or modules. Words such as "include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0027] Hereinafter, various embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. It should be noted that in the accompanying drawings, the same reference numerals are given to components having substantially the same or similar structures and functions, and repeated descriptions thereof will be omitted.

[0028] Unless otherwise specified, the “connection” described in this application refers to electrical connection.

[0029] In order to implement high reliability protection for the external power input terminal, the present application provides the following embodiments: In some embodiments, Figure 1 As shown, an input protection circuit has a voltage input terminal A and a voltage output terminal B.

[0030] The input protection circuit includes: a monitoring module 100 and a protection module 200 .

[0031] From the voltage input terminal A, through the monitoring module 100 and the protection module 200 connected to the monitoring module to the voltage output terminal B, a power supply branch is formed; There is also a first protection branch between the monitoring module 100 and the protection module 200, which is used to protect the voltage output terminal; The second protection branch is used to enable or disconnect the external power supply module; the third protection branch is used to implement surge protection for the voltage input terminal.

[0032] Specifically, Figure 2 As shown, the monitoring module 100 has: a first monitoring port 100a, a second monitoring port 100b, a first control port 100c, a second control port 100d and a third control port 100e; The protection module 200 has: a first receiving port 200a, a second receiving port 200b, a third receiving port 200c, a first output port 200d, a second output port 200e, a third output port 200f and a fourth output port 200g; The first monitoring port 100a is connected to the fourth output port 200g as a voltage input terminal A, the second monitoring port 100b is connected to the first output port 200d, the second output port 200e is used as a voltage output terminal B, the first control port 100c is connected to the first receiving port 200a to form a first protection branch, the second control port 100d is connected to the second receiving port 200b to form a second protection branch, and the third control port 100e is connected to the third receiving port 200c to form a third protection branch; The third output port 200f is used to provide an enable signal to the external power supply module to enable or disconnect the external power supply module.

[0033] Specifically, the monitoring module 100 includes: a detection unit 110 , a trigger unit 120 and a first resistor R1 .

[0034] Since the first resistor R1 is used to collect the current flowing through the power supply branch, preferably, a precision resistor is selected as the first resistor R1. A precision resistor is a resistor component with high precision, low temperature drift, and high reliability. The precision can reach 0.01%, and the temperature drift can reach 1PPM. By using a precision resistor, the sampling accuracy of the detection unit 110 for the power supply branch current can be improved.

[0035] The detection unit 110 has: a first detection port 110a, a second detection port 110b, a third detection port 110c and a status signal sending port 110d; The trigger unit 120 has: a first signal port 120a, a second signal port 120b, a third signal port 120c and a state signal receiving port 120d; The first detection port 110a is connected to the second detection port 110b and one end of the first resistor R1 as the first monitoring port 100a, the third detection port 110c is connected to the other end of the first resistor R1 as the second monitoring port 100b, the status signal sending port 110d is connected to the status signal receiving port 120d, the first signal port 120a is used as the first control port 100c, the second signal port 120b is used as the second control port 100d, and the third signal port 120c is used as the third control port 100e.

[0036] like Figure 3 As shown, the detection unit 110 includes: Analog-to-digital converter 111, first voltage register 112, first current register 113, first selection switch K1 and first signal interface 114; analog-to-digital converter 111 has: first voltage acquisition port 111a, first current acquisition port 111b and second current acquisition port 111c; first voltage acquisition port 111a serves as first detection port 110a, first current acquisition port 111b serves as second detection port 110b, second current acquisition port 111c serves as third detection port 110c; first signal transmission port in first signal interface 114 serves as status signal sending port 110d.

[0037] The analog-to-digital converter 111 is connected to the first voltage register 112 and the first current register 113 respectively through the first selection switch K1 , and is used to send the acquired voltage signal to the first voltage register 112 , and send the acquired current signal to the first current register 113 .

[0038] The first current acquisition port 111b and the second current acquisition port 111c are connected to the two ends of the first resistor R1 respectively. The current flowing through the first resistor R1, that is, the current of the power supply branch, can be calculated by the voltage difference between the two ends of the first resistor R1 and the resistance value of the first resistor R1:

[0039] in, I D1 represents the current value flowing through the first resistor R1, V 1 represents the voltage value of the first current acquisition port 111b, V 2 represents the voltage value of the second current acquisition port 111c,R 1 represents the resistance value of the first resistor R1.

[0040] The first voltage acquisition port 111 a is used to acquire the cathode voltage of the first diode D1 .

[0041] The analog-to-digital converter 111 is used to convert the collected analog quantity into a digital quantity, and save the converted voltage value in the first voltage register 112 and the converted current value in the first current register 113 through the first selection switch K1. The voltage value saved in the first voltage register 112 and the current value saved in the first current register 113 are transmitted through I 2 C bus is transmitted to the trigger unit 120.

[0042] like Figure 4 As shown, the trigger unit 120 includes: A digital-to-analog converter 121, a second voltage register 122, a second current register 123, a second selection switch K2, a second signal interface 124, a first comparator 125, a second comparator 126 and a NOR gate 127; The digital-to-analog converter 121 has: a first voltage output port 121 a and a second voltage output port 121 b ; The NOR gate 127 has: a first logic input port 127a, a second logic input port 127b and a logic output port 127c; The second signal transmission port in the second signal interface 124 serves as a status signal receiving port 120d; The first voltage output port 121a is connected to the non-inverting input port of the first comparator 125, and the inverting input port of the first comparator 125 is connected to the first reference voltage V ref1 , the output port of the first comparator 125 serves as the third signal port 120c, The second voltage output port 121b is connected to the non-inverting input port of the second comparator 126, and the inverting input port of the second comparator is connected to the second reference voltage V ref2 , the output port of the second comparator 126 serves as the second signal port 120b, The output port of the first comparator 125 is also connected to the first logic input port 127 a , the output port of the second comparator is also connected to the second logic input port 127 b , and the logic output port 127 c serves as the first signal port 120 a .

[0043] The trigger unit 120 uses I 2 C bus, the detection unit receives the digitized voltage and current.

[0044] The digitized voltage and current are converted into analog quantities by a digital-to-analog converter, and the analog voltage and current are processed by a first comparator 125 and a second comparator 126 respectively. ref1 and the second reference voltage V ref2 The specific value of can be set according to the actual situation. The first reference voltage V ref1 and the second reference voltage V ref2 It can respond to voltage overshoot and current overflow in a timely manner. The maximum overshoot voltage is usually set to the maximum clamping voltage of the transient voltage suppression diode, which should be 1.1~1.2 times the cathode voltage of the first diode when the circuit is working normally. The maximum current is usually set to the maximum current when the circuit is working normally.

[0045] like Figure 5 As shown, the protection module 200 includes: an output protection unit 210, a power protection unit 220 and a surge protection unit 230; The output protection unit 210 has: a first output protection port 210a, a second output protection port 210b and a third output protection port 210c; The power protection unit 220 has: a first power protection port 220a and a second power protection port 220b; The surge protection unit 230 has: a first surge protection port 230a and a second surge protection port 230b; The first output protection port 210a serves as the first receiving port 200a, the second output protection port 210b serves as the first output port 200d, the third output protection port 210c serves as the second output port 200e, the first power protection port 220a serves as the second receiving port 200b, the second power protection port 220b serves as the third output port 200f, the first surge protection port 230a serves as the third receiving port 200c, and the second surge protection port 230b serves as the fourth output port 200g.

[0046] Specifically, the output protection unit 210 includes a first switch device T1; The first switch device T1 has: a first electrode T 11 , the second electrode T of the first switching device 12 and the third electrode T of the first switching device 13 ; The first switch device first electrode T 11 As the first output protection port 210a, the second electrode T of the first switch device 12 As the second output protection port 210b, the third electrode T of the first switch device 13 As the third output protection port 210c.

[0047] Preferably, the first switch device is an N-channel metal-oxide-semiconductor transistor. When an N-channel metal-oxide-semiconductor transistor is used as the first switch device, the first electrode T of the first switch device 11 is the gate, the second pole T of the first switching device 12 is the drain, the third electrode T of the first switching device 13 When the gate-source voltage of the first switch device is greater than the threshold voltage, the first switch device is turned on; when the gate-source voltage of the first switch device is less than the threshold voltage, the first switch device is turned off.

[0048] Specifically, the power protection unit 220 includes a second switch device T2; The second switch device T2 has: a first electrode T 21 , the second switch device second electrode T 22 ; The first electrode T of the second switching device 21 As the first power protection port 220a, the second switch device second electrode T 22 As the second power protection port 220b. The third pole T of the second switch device 23 Ground.

[0049] Preferably, the second switch device is an N-channel metal-oxide-semiconductor transistor. When an N-channel metal-oxide-semiconductor transistor is used as the second switch device, the first electrode T of the second switch device 21 is the gate, the second electrode T of the second switching device 22 is the drain, the third electrode T of the second switching device 23 When the gate-source voltage of the second switch device is greater than the threshold voltage, the second switch device is turned on; when the gate-source voltage of the second switch device is less than the threshold voltage, the second switch device is turned off.

[0050] Specifically, the surge protection unit 230 includes a third switching device T3 and a first diode D1; The third switch device T3 has: a first electrode T 31 , the second electrode T of the third switching device 32 ; The first electrode T of the third switching device 31 As the first surge protection port 230a, the second electrode T of the third switch device 32 Being connected to the anode of the first diode D1 , the cathode of the first diode D1 serves as the second surge protection port 230 b .

[0051] Preferably, the third switch device is an N-channel metal-oxide-semiconductor transistor. When an N-channel metal-oxide-semiconductor transistor is used as the third switch device, the first electrode T of the third switch device 31 is the gate, the second pole T of the third switching device 32 is the drain, the third electrode T of the third switch device 33 When the gate-source voltage of the third switch device is greater than the threshold voltage, the third switch device is turned on; when the gate-source voltage of the third switch device is less than the threshold voltage, the third switch device is turned off.

[0052] The first diode D1 is a transient voltage suppression diode, which is used to protect the back-end electronic components from being damaged by voltage spikes.

[0053] Preferably, if Figure 6 As shown, the circuit also includes a second diode D2; A cathode of the second diode D2 is connected to the voltage output terminal B, and an anode of the second diode D2 is grounded.

[0054] The second diode D2 is a Schottky diode, which is usually used for freewheeling of the output circuit.

[0055] Preferably, the circuit further comprises at least one capacitor C; One end of any capacitor C among the at least one capacitor C is connected to the second monitoring port 100 b , and the other end of any capacitor C among the at least one capacitor C is grounded.

[0056] The capacitor mounted on the circuit board is a fragile electronic component. If it is physically hit or bumped, it is easy to cause a short circuit in the internal structure of the capacitor. When the external power supply module is connected to the input protection circuit, if no special protection is given, the capacitor short circuit will cause the voltage output terminal of the external power supply module to short to the ground, and the large current generated will burn the circuit board.

[0057] Alternatively, if Figure 7 As shown, the input protection circuit further includes: an external power supply module 300; The external power supply module 300 has: a power supply output port 300a and a power supply enable port 300b; The power output port 300a is connected to the voltage input terminal A, and the power enable port 300b is connected to the third output port 200f.

[0058] Preferably, the external power supply module 300 includes: a second resistor R2; One end of the second resistor R2 is used as the power supply enable port 300b, and the other end of the second resistor R2 is connected to the working voltage V CC , so that when the external power supply module 300 works normally, the power supply enable port 300b is at a low level.

[0059] When the circuit works normally, the power supply enable port 300 b is at a low level, and the low level enables the external power supply module 300 to supply power to the voltage input terminal A when in place.

[0060] When either the first switch device T1 or the third switch device T3 is turned off, the power supply enable port 300 b is at a high level, and the power supply from the external power supply module 300 to the voltage input terminal A is cut off.

[0061] Through the coordinated use of the monitoring module and the protection module, when the current of the power supply branch exceeds the current threshold, the power supply of the external power supply module to the voltage input terminal is disconnected; when the voltage at the voltage input terminal exceeds the voltage threshold, the external power supply module is turned off, and the power supply branch is turned off to implement effective protection for the input terminal: to avoid voltage overshoot damaging the transient voltage suppression diode; to avoid capacitor short circuit causing large current and burning the board.

[0062] In other embodiments, Figure 8 As shown, a circuit board comprises the input protection circuit described in the first aspect.

[0063] Preferably, the circuit board is a printed circuit board.

[0064] The circuit board has a first surface and a second surface arranged opposite to each other; A first switching device T1 is disposed on the first surface of the circuit board, and a second diode D2 is disposed on the second surface of the circuit board; The pin of the cathode of the second diode D2 is connected to the third electrode T of the first switch device. 13 The pins are electrically connected through the same through hole.

[0065] By arranging the transient voltage suppression diode and the Schottky diode on the surface opposite to the surface on which the first switch device is arranged, the transient voltage suppression diode and the Schottky diode can be accommodated at the same time, thus saving the circuit board area.

[0066] In other embodiments, Fig. 9 As shown, a circuit input protection method is applied to the input protection circuit described above, comprising: S100: Connecting the power supply output port of the external power supply module to the voltage input terminal; S200: Acquire the current flowing through the power supply branch and the voltage at the voltage input terminal through the monitoring module; S300: Determine whether the current flowing through the power supply branch exceeds a current threshold, and determine whether the voltage at the voltage input terminal exceeds a voltage threshold; S400: In response to the current flowing through the power supply branch not exceeding the current threshold and the voltage at the voltage input terminal not exceeding the voltage threshold, the monitoring module transmits a first control signal to the first receiving port to control the first switching device to be turned on, transmits a second control signal to the second receiving port to control the second switching device to be turned on, and transmits a third control signal to the third receiving port to control the third switching device to be turned on.

[0067] Optionally, the circuit input protection method further includes: S400ʹ: In response to the current flowing through the power supply branch exceeding the current threshold, the monitoring module transmits a second control signal to the second receiving port, and disconnects the power supply from the external power supply module to the voltage input terminal by turning off the second switch device.

[0068] Optionally, the circuit input protection method further includes: S400ʹʹ: In response to the voltage at the voltage input terminal exceeding the voltage threshold, the monitoring module transmits a third control signal to the third receiving port to protect the first diode by turning off the third switch device; and transmits a first control signal to the first receiving port to disconnect the power supply branch by turning off the first switch device.

[0069] By implementing an input protection circuit, circuit board and input protection method disclosed in the embodiment of the present application, through the coordinated use of the monitoring module and the protection module, when the current of the power supply branch exceeds the current threshold, the power supply of the external power supply module to the voltage input terminal is disconnected; when the voltage at the voltage input terminal exceeds the voltage threshold, the external power supply module is turned off, and the power supply branch is turned off, so as to implement effective protection for the input terminal: avoid damage to the transient voltage suppression diode caused by voltage overshoot, surge phenomenon, etc.; avoid burning the board due to large current caused by capacitor short circuit. By arranging the transient voltage suppression diode and the Schottky diode on the surface opposite to the surface of the first switch device, the transient voltage suppression diode and the Schottky diode can be accommodated at the same time, saving the circuit board area.

[0070] All the above optional technical solutions can be arbitrarily combined to form optional embodiments of the present application, which will not be described one by one here.

[0071] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made to those skilled in the art without departing from the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of this application should be included in the scope of protection of this application. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may also include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. An input protection circuit, characterized in that: The input protection circuit has a voltage input terminal and a voltage output terminal, and the input protection circuit includes: a monitoring module and a protection module; A power supply branch is formed from the voltage input end, through the monitoring module and the protection module connected to the monitoring module to the voltage output end; The first control port of the monitoring module is connected to the first receiving port of the protection module to form a first protection branch, and the first protection branch is used to protect the voltage output terminal; The second control port of the monitoring module is connected to the second receiving port of the protection module to form a second protection branch, and the second protection branch is used to enable or disconnect the external power supply module; The third control port of the monitoring module is connected to the third receiving port of the protection module to form a third protection branch, and the third protection branch is used to implement surge protection for the voltage input terminal.

2. The input protection circuit according to claim 1, characterized in that: The monitoring module also has: a first monitoring port and a second monitoring port; The protection module further has: a first output port, a second output port, a third output port and a fourth output port; The first monitoring port is connected to the fourth output port as the voltage input port, the second monitoring port is connected to the first output port, and the second output port is used as the voltage output port; The third output port is used to provide an enable signal to the external power supply module to enable or disconnect the external power supply module.

3. The input protection circuit according to claim 2, characterized in that: The monitoring module includes: a detection unit, a trigger unit and a first resistor; The detection unit has: a first detection port, a second detection port, a third detection port and a status signal sending port; The trigger unit has: a first signal port, a second signal port, a third signal port and a status signal receiving port; The first detection port is connected to the second detection port and one end of the first resistor as the first monitoring port, the third detection port is connected to the other end of the first resistor as the second monitoring port, the status signal sending port is connected to the status signal receiving port, the first signal port is used as the first control port, the second signal port is used as the second control port, and the third signal port is used as the third control port.

4. The input protection circuit according to claim 3, characterized in that: The detection unit comprises: An analog-to-digital converter, a first voltage register, a first current register, a first selection switch and a first signal interface; The analog-to-digital converter has: a first voltage acquisition port, a first current acquisition port and a second current acquisition port; The first voltage acquisition port serves as the first detection port, the first current acquisition port serves as the second detection port, and the second current acquisition port serves as the third detection port; The first signal transmission port in the first signal interface serves as a status signal sending port; The analog-to-digital converter is connected to the first voltage register and the first current register respectively through the first selection switch, and is used to send the acquired voltage signal to the first voltage register and send the acquired current signal to the first current register.

5. The input protection circuit according to claim 3, characterized in that: The trigger unit comprises: A digital-to-analog converter, a second voltage register, a second current register, a second selection switch, a second signal interface, a first comparator, a second comparator, and a NOR gate; The digital-to-analog converter has: a first voltage output port and a second voltage output port; The NOR gate has: a first logic input port, a second logic input port and a logic output port; The second signal transmission port in the second signal interface serves as the status signal receiving port; The first voltage output port is connected to the non-inverting input port of the first comparator, the inverting input port of the first comparator is connected to a first reference voltage, and the output port of the first comparator serves as a third signal port. The second voltage output port is connected to the non-inverting input port of the second comparator, the inverting input port of the second comparator is connected to the second reference voltage, and the output port of the second comparator is used as the second signal port. The output port of the first comparator is also connected to the first logic input port, the output port of the second comparator is also connected to the second logic input port, and the logic output port serves as the first signal port.

6. The input protection circuit according to claim 3, characterized in that: The first resistor is a precision resistor.

7. The input protection circuit according to claim 2, characterized in that: The protection module includes: an output protection unit, a power protection unit and a surge protection unit; The output protection unit has: a first output protection port, a second output protection port and a third output protection port; The power protection unit has: a first power protection port and a second power protection port; The surge protection unit has: a first surge protection port and a second surge protection port; The first output protection port serves as the first receiving port, the second output protection port serves as the first output port, the third output protection port serves as the second output port, the first power supply protection port serves as the second receiving port, the second power supply protection port serves as the third output port, the first surge protection port serves as the third receiving port, and the second power supply protection port serves as the fourth output port.

8. The input protection circuit according to claim 7, characterized in that: The output protection unit includes a first switching device; The first switch device comprises: a first switch device first pole, a first switch device second pole and a first switch device third pole; The first pole of the first switch device serves as the first output protection port, the second pole of the first switch device serves as the second output protection port, and the third pole of the first switch device serves as the third output protection port.

9. The input protection circuit according to claim 7, characterized in that: The power protection unit includes a second switch device; The second switch device comprises: a second switch device first pole and a second switch device second pole; The first pole of the second switch device serves as the first power protection port, and the second pole of the second switch device serves as the second power protection port.

10. The input protection circuit according to claim 7, characterized in that: The surge protection unit includes a third switch device and a first diode; The third switch device comprises: a third switch device first electrode and a third switch device second electrode; The first electrode of the third switch device serves as the first surge protection port, the second electrode of the third switch device serves as a connection to the anode of the first diode, and the cathode of the first diode serves as the second power protection port.

11. The input protection circuit according to claim 1, characterized in that: The circuit also includes a second diode; A cathode of the second diode is connected to the voltage output terminal, and an anode of the second diode is grounded.

12. The input protection circuit according to claim 1, characterized in that: The circuit further comprises at least one capacitor; One end of any one of the at least one capacitor is connected to the second monitoring port, and the other end of any one of the at least one capacitor is grounded.

13. The input protection circuit according to any one of claims 1 to 12, characterized in that: The circuit further comprises: an external power supply module; The external power supply module has: a power supply output port and a power supply enable port; The power supply output port is connected to the voltage input terminal, and the power supply enable port is connected to the third output port.

14. The input protection circuit according to claim 13, characterized in that: The external power supply module includes: a second resistor; One end of the second resistor serves as the power supply enable port, and the other end of the second resistor is connected to a working voltage, so that when the external power supply module works normally, the power supply enable port is at a low level.

15. A circuit board, characterized in that: The circuit board comprises the input protection circuit according to any one of claims 1 to 14; The circuit board has a first surface and a second surface arranged opposite to each other; A first switching device is disposed on the first surface of the circuit board, and a second diode is disposed on the second surface of the circuit board; The pin of the cathode of the second diode is electrically connected to the pin of the third electrode of the first switch device through the same through hole.

16. An input protection method, characterized in that: The method is applied to the input protection circuit according to any one of claims 1 to 14, comprising: Connect the power supply output port of the external power supply module to the voltage input terminal; The current flowing through the power supply branch and the voltage at the voltage input terminal are obtained through the monitoring module; Determine whether the current flowing through the power supply branch exceeds the current threshold, and determine whether the voltage at the voltage input terminal exceeds the voltage threshold; In response to the current flowing through the power supply branch not exceeding the current threshold and the voltage at the voltage input terminal not exceeding the voltage threshold, the monitoring module transmits a first control signal to the first receiving port to control the first switching device to turn on, transmits a second control signal to the second receiving port to control the second switching device to turn on, and transmits a third control signal to the third receiving port to control the third switching device to turn on.

17. The input protection method according to claim 16, characterized in that: The method further comprises: In response to the current flowing through the power supply branch exceeding the current threshold, the monitoring module transmits a second control signal to the second receiving port, and disconnects the power supply from the external power supply module to the voltage input terminal by turning off the second switch device.

18. The input protection method according to claim 16, characterized in that: The method further comprises: In response to the voltage at the voltage input terminal exceeding the voltage threshold, the monitoring module transmits a third control signal to the third receiving port to protect the first diode by turning off the third switching device; and transmits a first control signal to the first receiving port to disconnect the power supply branch by turning off the first switching device.

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