Hot plug protection circuit and keyboard

Abstract

The utility model discloses a hot plug protection circuit and a keyboard, and relates to the hot plug technology field, the hot plug protection circuit comprises a first switch circuit, a voltage sampling circuit, a current sampling circuit and a comparison circuit, an input end of the first switch circuit is electrically connected with a power supply input end, and an output end of the first switch circuit is electrically connected with a power supply output end. The output end of the first switching circuit is electrically connected with the power output end, the sampling end of the voltage sampling circuit is electrically connected with the power input end, the controlled end of the first switching circuit is electrically connected with the output end of the voltage sampling circuit, and the sampling end of the current sampling circuit is electrically connected with the power input end. A first input end of the comparison circuit is electrically connected with an output end of the current sampling circuit, a second input end of the comparison circuit is connected with a preset voltage value, and an output end of the comparison circuit is electrically connected with a controlled end of the first switching circuit; the utility model aims to avoid the influence of surge current or transient voltage generated by the USB connector in the hot plug process on the internal circuit of the keyboard.

Description

Technical Field

[0001] The utility model relates to the technical field of hot plugging, and particularly relates to a hot plugging protection circuit and a keyboard. Background Art

[0002] When plugging or unplugging a USB connector, for example, when a keyboard is connected to or disconnected from a host computer through a USB connector, since there are components such as capacitors or inductors inside the interface of the host computer for connecting the USB connector, surge current and transient voltage may be generated during the discharge process of the capacitor or inductor. The surge current and transient voltage can damage the main board and other circuits of the keyboard. Summary of the Utility Model

[0003] The main object of the utility model is to propose a hot plugging protection circuit and a keyboard, aiming to avoid the influence of surge current or transient voltage generated during the hot plugging of the USB connector on the internal circuit of the keyboard.

[0004] To achieve the above object, a hot plugging protection circuit proposed by the utility model is applied to a keyboard. The keyboard includes a power input terminal and a power output terminal. The hot plugging protection circuit includes:

[0005] A first switch circuit, the input end of the first switch circuit is electrically connected to the power input terminal, and the output end of the first switch circuit is electrically connected to the power output terminal;

[0006] A voltage sampling circuit, the sampling end of the voltage sampling circuit is electrically connected to the power input terminal, the controlled end of the first switch circuit is electrically connected to the output end of the voltage sampling circuit, and the voltage sampling circuit is used to detect the voltage of the power input terminal and output a corresponding voltage detection signal to control the conduction / turn-off of the first switch circuit;

[0007] A current sampling circuit, the sampling end of the current sampling circuit is electrically connected to the power input terminal, and the current sampling circuit is used to sample the current of the power input terminal and output a corresponding current detection signal;

[0008] A comparison circuit, the first input end of the comparison circuit is electrically connected to the output end of the current sampling circuit, the second input end of the comparison circuit is connected to a preset voltage value, and the output end of the comparison circuit is electrically connected to the controlled end of the first switch circuit. The comparison circuit is used to compare the magnitudes of the current detection signal and the preset voltage value and control the conduction / turn-off of the first switch circuit according to the comparison result.

[0009] In an embodiment, the voltage sampling circuit includes:

[0010] A second switching circuit and a first voltage dividing circuit, wherein the input end and the controlled end of the second switching circuit are both electrically connected to the power input end, the output end of the second switching circuit and the output end of the comparison circuit are both electrically connected to the first end of the first voltage dividing circuit, and the second end of the first voltage dividing circuit is electrically connected to the controlled end of the first switching circuit.

[0011] In one embodiment, the second switching circuit includes:

[0012] A first zener diode, a second zener diode, a first resistor, a second resistor, a third resistor and a first switching transistor, wherein the first end of the first resistor is electrically connected to the power input end, the second end of the first resistor is respectively electrically connected to the first end of the second resistor and the cathode of the first zener diode, the anode of the first zener diode is grounded, the second end of the second resistor is respectively electrically connected to the anode of the second zener diode and the controlled end of the first switching transistor, the cathode of the second zener diode and the input end of the first switching transistor are both electrically connected to the power input end, the output end of the first switching transistor is respectively electrically connected to the second end of the third resistor and the first end of the first voltage dividing circuit, and the first end of the third resistor is electrically connected to the power input end.

[0013] In one embodiment, the first voltage dividing circuit includes:

[0014] A fourth resistor and a fifth resistor, wherein the first end of the fourth resistor is electrically connected to the controlled end of the first switching circuit, the second end of the fourth resistor is electrically connected to the first end of the fifth resistor, the first end of the fifth resistor is also respectively electrically connected to the output end of the comparison circuit and the output end of the first switching transistor, and the second end of the fifth resistor is grounded.

[0015] In one embodiment, the current sampling circuit includes:

[0016] a third switching transistor, a fourth switching transistor, a fifth switching transistor, a first operational amplifier, and a sixth resistor. The input end of the third switching transistor is electrically connected to the power input end. The output end of the third switching transistor is electrically connected to the input end of the first switching circuit. The input end of the fourth switching transistor is electrically connected to the power input end. The controlled end of the fourth switching transistor is electrically connected to the controlled end of the third switching transistor. The output end of the fourth switching transistor is electrically connected to the input end of the fifth switching transistor. The output end of the fifth switching transistor is electrically connected to the first end of the sixth resistor. The second end of the sixth resistor is grounded. The first input end of the comparison circuit is electrically connected to the first end of the sixth resistor. The inverting end of the first operational amplifier is electrically connected to the output end of the third switching transistor. The non-inverting end of the first operational amplifier is electrically connected to the output end of the fourth switching transistor. The output end of the first operational amplifier is electrically connected to the controlled end of the fifth switching transistor.

[0017] In one embodiment, the first switching circuit includes:

[0018] a sixth switching transistor, a seventh resistor, and a first capacitor. The input end of the sixth switching transistor is electrically connected to the power input end. The output end of the sixth switching transistor is electrically connected to the power output end. The controlled end of the sixth switching transistor is electrically connected to the output ends of the current sampling circuit and the voltage sampling circuit respectively. The first end of the first capacitor is electrically connected to the input end of the sixth switching transistor. The second end of the first capacitor is electrically connected to the controlled end of the sixth switching transistor. The first end of the seventh resistor is electrically connected to the controlled end of the sixth switching transistor. The second end of the seventh resistor is grounded.

[0019] In one embodiment, the hot-swap protection circuit further includes:

[0020] an eighth resistor and a ninth resistor. The first end of the eighth resistor is electrically connected to the power output end. The second end of the eighth resistor is electrically connected to the first end of the ninth resistor. The second end of the ninth resistor is grounded.

[0021] In one embodiment, the keyboard further includes a plurality of signal transmission ends, and the hot-swap protection circuit further includes:

[0022] a plurality of the transient suppression diodes. The first ends of the plurality of transient suppression diodes are electrically connected to the power input end and the plurality of signal transmission ends one by one. The second ends of the plurality of transient suppression diodes are all grounded.

[0023] The present utility model further provides a keyboard, including the hot-swap protection circuit described in any one of the above.

[0024] The technical solution of the present utility model samples the current at the power input end through a current sampling circuit and outputs a corresponding current detection signal. The comparison circuit is used to compare the voltage of the current detection signal with a preset voltage value. When the voltage of the current detection signal is greater than the preset voltage value, it indicates that the current at the power input end is too large. The comparison circuit outputs a corresponding control signal (such as high / low level) to control the first switch circuit to turn off, so as to disconnect the path between the power input end and the power output end, and avoid the surge current flowing through the power output end to the subsequent circuit and affecting the subsequent circuit. It also samples the voltage at the power input end through a voltage sampling circuit and outputs a corresponding voltage detection signal. When the voltage at the power input end is too large, the voltage detection signal also becomes larger / smaller and is higher / lower than the conduction threshold of the first switch circuit, so that the first switch circuit is disconnected, and the path between the power input end and the power output end is disconnected, avoiding the impact of transient voltage on the subsequent circuit. With such a setting, in practical applications, when the keyboard is connected to or disconnected from the host computer through a USB connector, it will no longer be affected by transient voltage or surge current, which can significantly improve the safety, stability, service life and user experience of the keyboard. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following described drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0026] Figure 1 It is a schematic diagram of modules according to an embodiment of the present utility model;

[0027] Figure 2 It is a schematic diagram of the circuit structure according to an embodiment of the present utility model;

[0028] Figure 3 It is a schematic diagram of the circuit structure according to another embodiment of the present utility model;

[0029] Figure 4 It is a schematic diagram of the circuit structure according to still another embodiment of the present utility model;

[0030] Figure 5 It is a schematic diagram of the circuit structure according to yet another embodiment of the present utility model.

[0031] Explanation of the reference numerals in the drawings:

[0032] 10. First switch circuit; 20. Voltage sampling circuit; 21. Second switch circuit; 22. First voltage dividing circuit; 30. Current sampling circuit; 40. Comparison circuit.

[0033] The realization, functional features, and advantages of the purpose of the present utility model will be further described in conjunction with embodiments and with reference to the accompanying drawings. Specific embodiments

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present utility model with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present utility model.

[0035] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present utility model, then such directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If this specific posture changes, then the directional indications will also change accordingly.

[0036] In addition, if there are descriptions such as "first", "second", etc. involved in the embodiments of the present utility model, then such descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or a solution where A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present utility model.

[0037] When plugging and unplugging a USB connector, for example, when a keyboard is connected to or disconnected from a host computer through a USB connector, since there are components such as capacitors or inductors inside the interface of the host computer for connecting the USB connector, surge current and transient voltage may be generated during the discharge process of the capacitor or inductor. The surge current and transient voltage can damage the main board and other circuits of the keyboard.

[0038] For this reason, the present utility model proposes a hot-swap protection circuit and a keyboard, aiming to avoid the influence of surge current or transient voltage generated during the hot-swap process of the USB connector on the internal circuit of the keyboard.

[0039] Reference Figure 1, in an embodiment of the present utility model, a hot-swap protection circuit is applied to a keyboard. The keyboard includes a power input terminal and a power output terminal. The hot-swap protection circuit includes:

[0040] A first switch circuit 10, the input terminal of the first switch circuit 10 is electrically connected to the power input terminal, and the output terminal of the first switch circuit 10 is electrically connected to the power output terminal;

[0041] A voltage sampling circuit 20, the sampling terminal of the voltage sampling circuit 20 is electrically connected to the power input terminal, the controlled terminal of the first switch circuit 10 is electrically connected to the output terminal of the voltage sampling circuit 20, and the voltage sampling circuit 20 is used to detect the voltage of the power input terminal and output a corresponding voltage detection signal to control the conduction / shutdown of the first switch circuit 10;

[0042] A current sampling circuit 30, the sampling terminal of the current sampling circuit 30 is electrically connected to the power input terminal, and the current sampling circuit 30 is used to sample the current of the power input terminal and output a corresponding current detection signal;

[0043] A comparison circuit 40, the first input terminal of the comparison circuit 40 is electrically connected to the output terminal of the current sampling circuit 30, the second input terminal of the comparison circuit 40 is connected to a preset voltage value, and the output terminal of the comparison circuit 40 is electrically connected to the controlled terminal of the first switch circuit 10. The comparison circuit 40 is used to compare the magnitudes of the current detection signal and the preset voltage value and control the conduction / shutdown of the first switch circuit 10 according to the comparison result.

[0044] In this embodiment, the current sampling circuit 30 can be implemented by any one of a current transformer, a Hall sensor, or a shunt resistor sampling. The voltage sampling circuit 20 can be implemented by any one of a resistor voltage division circuit, a voltage transformer, or an analog-to-digital converter.

[0045] In this embodiment, the comparison circuit 40 can be implemented by a main controller, such as an MCU (Microcontroller Unit, micro control unit), a DSP (Digital Signal Process, digital signal processing chip), an FPGA (Field Programmable Gate Array, programmable logic gate array chip), an SOC (System On Chip, system-level chip), etc.; it can also be implemented by a comparator circuit. The non-inverting terminal of the comparator circuit is connected to the output terminal of the current sampling circuit 30, and the inverting terminal is connected to the preset voltage value. When the current detection signal is greater than the preset voltage value, the comparator circuit outputs a high-level signal to control the shutdown of the first switch circuit 10.

[0046] In this embodiment, the first switch circuit 10 may adopt at least one switching device such as a triode, a MOS transistor, or an IGBT transistor. The comparison circuit 40 or the voltage detection signal can control the on / off of the switching device by controlling the controlled end of the switching device, and turn on / off the path between the power input terminal and the power output interface.

[0047] In this embodiment, specifically, the technical solution of the present utility model samples the current at the power input terminal through the current sampling circuit 30 and outputs a corresponding current detection signal. The comparison circuit 40 is used to compare the voltage of the current detection signal with a preset voltage value. When the voltage of the current detection signal is greater than the preset voltage value, it indicates that the current at the power input terminal is too large. The comparison circuit 40 outputs a corresponding control signal (such as high / low level) to control the first switch circuit 10 to turn off, so as to disconnect the path between the power input terminal and the power output terminal, and avoid the surge current flowing through the power output terminal to the subsequent circuit and affecting the subsequent circuit. It also samples the voltage at the power input terminal through the voltage sampling circuit 20 and outputs a corresponding voltage detection signal. When the voltage at the power input terminal is too large, the voltage detection signal also becomes larger / smaller and is higher / lower than the conduction threshold of the first switch circuit 10, so that the first switch circuit 10 is disconnected, and the path between the power input terminal and the power output terminal is disconnected, avoiding the impact of transient voltage on the subsequent circuit. With such a setting, in practical applications, when the keyboard is connected to or disconnected from the host computer through the USB connector, it will no longer be affected by transient voltage or surge current, which can significantly improve the safety, stability, service life, and user experience of the keyboard.

[0048] In an embodiment of the present utility model, the voltage sampling circuit 20 includes:

[0049] A second switch circuit 21 and a first voltage dividing circuit 22. The input terminal and the controlled end of the second switch circuit 21 are both electrically connected to the power input terminal. The output terminal of the second switch circuit 21 and the output terminal of the comparison circuit 40 are electrically connected to the first end of the first voltage dividing circuit 22. The second end of the first voltage dividing circuit 22 is electrically connected to the controlled end of the first switch circuit 10.

[0050] In this embodiment, the second switching circuit 21 can adopt at least one switching device such as a triode, a MOS transistor, or an IGBT transistor. The second switching circuit 21 can adjust the conduction threshold of the switching device in the second switching circuit 21 in the form of resistor voltage division, so that when the voltage at the power input terminal is greater than or equal to a preset value, the voltage at the controlled terminal of the second switching circuit 21 is greater than or equal to the conduction threshold, the second switching circuit 21 conducts, and part of the current at the power input terminal flows through the second switching circuit 21 to the first voltage dividing circuit 22 and then to the ground through the first voltage dividing circuit 22. At this time, the voltage value of the first voltage dividing circuit 22 increases. When the first switching circuit 10 adopts a PMOS transistor or a PNP triode, since the controlled terminal of the first switching circuit 10 is connected to the first voltage dividing circuit 22, the first switching circuit 10 turns off, and the path between the power input terminal and the power output terminal is disconnected, thereby avoiding the impact of transient voltage on the subsequent circuit.

[0051] In this embodiment, the second switching circuit 21 includes:

[0052] A first zener diode D1, a second zener diode D2, a first resistor R1, a second resistor R2, a third resistor R3, and a first switching transistor Q1. The first end of the first resistor R1 is electrically connected to the power input terminal. The second end of the first resistor R1 is respectively electrically connected to the first end of the second resistor R2 and the cathode of the first zener diode D1. The anode of the first zener diode D1 is grounded. The second end of the second resistor R2 is respectively electrically connected to the anode of the second zener diode D2 and the controlled terminal of the first switching transistor Q1. The cathode of the second zener diode D2 and the input terminal of the first switching transistor Q1 are both electrically connected to the power input terminal. The output terminal of the first switching transistor Q1 is respectively electrically connected to the second end of the third resistor R3 and the first end of the first voltage dividing circuit 22. The first end of the third resistor R3 is electrically connected to the power input terminal.

[0053] The first voltage dividing circuit 22 includes:

[0054] A fourth resistor R4 and a fifth resistor R5. The first end of the fourth resistor R4 is electrically connected to the controlled terminal of the first switching circuit 10. The second end of the fourth resistor R4 is electrically connected to the first end of the fifth resistor R5. The first end of the fifth resistor R5 is also respectively electrically connected to the output terminal of the comparison circuit 40 and the output terminal of the first switching transistor Q1. The second end of the fifth resistor R5 is grounded.

[0055] In this embodiment, the first switching transistor Q1 can adopt one of a triode, a MOS transistor, or an IGBT transistor.

[0056] In this embodiment, the first switching transistor Q1 is a PNP bipolar junction transistor. When the voltage at the power input terminal is too high, the first zener diode D1 conducts, and part of the current at the power input terminal flows to the ground through the first zener diode D1, so that the voltage at the control terminal of the first switching transistor Q1 is pulled down, and the first switching transistor Q1 conducts. Part of the current at the power input terminal flows through the first switching transistor Q1 to the fifth resistor R5, and the voltage of the fifth resistor R5 increases. When the first switching circuit 10 uses a PMOS transistor or a PNP bipolar junction transistor, the first switching circuit 10 is turned off, thereby turning off the path between the power input terminal and the power output terminal, thus avoiding the impact of the transient voltage on the subsequent circuit.

[0057] In this embodiment, the second zener diode D2 is used to protect the first switching transistor Q1 by limiting the reverse voltage between the base and the emitter of the first switching transistor Q1.

[0058] Reference Figure 2 , in an embodiment of the present invention, the current sampling circuit includes:

[0059] A third switching transistor Q3, a fourth switching transistor Q4, a fifth switching transistor Q5, a first operational amplifier U1, and a sixth resistor R6. The input terminal of the third switching transistor Q3 is electrically connected to the power input terminal, the output terminal of the third switching transistor Q3 is electrically connected to the input terminal of the first switching circuit 10, the input terminal of the fourth switching transistor Q4 is electrically connected to the power input terminal, the control terminal of the fourth switching transistor Q4 is electrically connected to the control terminal of the third switching transistor Q3, the output terminal of the fourth switching transistor Q4 is electrically connected to the input terminal of the fifth switching transistor Q5, the output terminal of the fifth switching transistor Q5 is electrically connected to the first end of the sixth resistor R6, the second end of the sixth resistor R6 is grounded, the first input terminal of the comparison circuit 40 is electrically connected to the first end of the sixth resistor R6, the inverting terminal of the first operational amplifier U1 is electrically connected to the output terminal of the third switching transistor Q3, the non-inverting terminal of the first operational amplifier U1 is electrically connected to the output terminal of the fourth switching transistor Q4, and the output terminal of the first operational amplifier U1 is electrically connected to the control terminal of the fifth switching transistor Q5.

[0060] In this embodiment, the third switching transistor Q3, the fourth switching transistor Q4, and the fifth switching transistor Q5 can each be one of a bipolar junction transistor, a MOS transistor, or an IGBT transistor.

[0061] In this embodiment, the third switching transistor Q3, the fourth switching transistor Q4, and the fifth switching transistor Q5 are all NMOS transistors. The on-resistance of the fourth switching transistor Q4 is much larger than that of the third switching transistor Q3, so that the fourth switching transistor Q4 reduces the impact on the main circuit during the process of collecting current. Since the first operational amplifier U1 and the fifth switching transistor Q5 form a negative feedback structure, and due to the virtual short characteristic of the first operational amplifier U1, the first operational amplifier U1 clamps the voltage at the output terminal of the third switching transistor Q3 to the voltage at the output terminal of the fourth switching transistor Q4, so that the voltage at the output terminal of the third switching transistor Q3 is equal to the voltage at the output terminal of the fourth switching transistor Q4. Also, since the control terminal of the third switching transistor Q3 is connected to the control terminal of the fourth switching transistor Q4, the voltage difference (gate-source voltage difference) between the control terminal and the output terminal of the third switching transistor Q3 is equal to the voltage difference between the control terminal and the output terminal of the fourth switching transistor Q4, so that the current collected by the fourth switching transistor Q4 always maintains a proportional relationship with the current flowing through the third switching transistor Q3, and the ratio is the ratio of the on-resistance of the fourth switching transistor Q4 to the on-resistance of the third switching transistor Q3. The first operational amplifier U1 outputs a high-level signal according to the voltages at the non-inverting terminal and the inverting terminal to control the fifth switching transistor Q5 to conduct, so that the current collected by the fourth switching transistor Q4 flows through the fifth switching transistor Q5 to the sixth resistor R6. The comparison circuit 40 obtains the corresponding voltage through the sixth resistor R6. When the obtained voltage is greater than the preset voltage value, it indicates that the current at the power input terminal is too large and has exceeded the preset current value. The comparison circuit 40 outputs a corresponding control signal to control the first switching circuit 10 to turn off, so as to disconnect the path between the power input terminal and the power output terminal, thereby avoiding the impact of inrush current on the subsequent circuit.

[0062] Reference Figure 3 , in an embodiment of the present invention, the first switching circuit 10 includes:

[0063] A sixth switching transistor Q6, a seventh resistor R7, and a first capacitor C1. The input terminal of the sixth switching transistor Q6 is electrically connected to the power input terminal, the output terminal of the sixth switching transistor Q6 is electrically connected to the power output terminal, the control terminal of the sixth switching transistor Q6 is respectively electrically connected to the output terminals of the current sampling circuit and the voltage sampling circuit, the first end of the first capacitor C1 is electrically connected to the input terminal of the sixth switching transistor Q6, the second end of the first capacitor C1 is electrically connected to the control terminal of the sixth switching transistor Q6, the first end of the seventh resistor R7 is electrically connected to the control terminal of the sixth switching transistor Q6, and the second end of the seventh resistor R7 is grounded.

[0064] In this embodiment, the sixth switching transistor Q6 is a PMOS transistor. When the current at the power input terminal is too large, the voltage of the current detection signal is greater than the preset voltage value, so that the comparison circuit 40 outputs a high-level signal to the seventh resistor R7. The voltage of the seventh resistor R7 increases, and the sixth switching transistor Q6 is turned off, thereby preventing the surge current from flowing to the subsequent circuit and affecting the subsequent circuit. When the voltage at the power input terminal is too large, the voltage of the voltage detection signal output by the voltage sampling circuit becomes larger, and the voltage value at the controlled terminal of the sixth switching transistor Q6 is greater than the voltage at the input terminal, and the sixth switching transistor Q6 is turned off, thereby preventing the transient voltage from affecting the subsequent circuit.

[0065] In this embodiment, the first capacitor C1 can play a filtering role in a high-frequency environment, avoiding the situation that the sixth switching transistor Q6 fails to work stably or even fails due to factors such as high-frequency noise.

[0066] Reference Figure 4 , in an embodiment of the present invention, the hot-swap protection circuit further includes:

[0067] An eighth resistor R8 and a ninth resistor R9. The first end of the eighth resistor R8 is electrically connected to the power output terminal, the second end of the eighth resistor R8 is electrically connected to the first end of the ninth resistor R9, and the second end of the ninth resistor R9 is grounded.

[0068] In this embodiment, when the current at the power input terminal flows to the power output terminal through the first switching circuit, part of the current will flow to the eighth resistor R8 and the ninth resistor R9. The keyboard detects the voltage of the ninth resistor R9 through the main control. When the voltage of the ninth resistor R9 increases, it indicates that the USB connector has been safely connected to the host computer. At this time, the keyboard can receive signals transmitted from multiple signal transmission terminals and communicate with the host computer through the multiple signal transmission terminals.

[0069] Reference Figure 5 , in an embodiment of the present invention, the keyboard further includes multiple signal transmission terminals, and the hot-swap protection circuit further includes:

[0070] Multiple transient suppression diodes D2. The first ends of the multiple transient suppression diodes D2 are electrically connected to the power input terminal and the multiple signal transmission terminals one by one, and the second ends of the multiple transient suppression diodes D2 are all grounded.

[0071] During the process of the USB connector contacting or separating from the USB port of the computer, due to the friction between materials, static charges may be generated. Especially in a dry environment, the static electricity will enter the subsequent circuit through the power input terminal and multiple signal transmission terminals and affect the subsequent circuit.

[0072] In this regard, in this embodiment, a transient suppression diode D2 is connected between the power input terminal and the multiple signal transmission terminals. When static electricity enters the power input terminal or the multiple signal transmission terminals, the transient suppression diode D2 conducts, and the static electricity is released to the ground, thereby preventing the static electricity from flowing into the subsequent circuit and affecting the subsequent circuit.

[0073] The present utility model also proposes a keyboard, which includes the hot-swap protection circuit as described above.

[0074] It should be noted that since the keyboard of the present utility model is based on the above-mentioned hot-swap protection circuit, therefore, the embodiments of the keyboard of the present utility model include all the technical solutions of all the embodiments of the above-mentioned hot-swap protection circuit, and the achieved technical effects are also exactly the same, which will not be elaborated here.

[0075] The above description is only an exemplary embodiment of the present utility model, and does not limit the patent scope of the present utility model. Any equivalent structural transformation made under the technical concept of the present utility model by using the content of the specification and drawings of the present utility model, or directly / indirectly applied to other related technical fields, is included in the patent protection scope of the present utility model.

Claims

1. A hot plug protection circuit is applied to a keyboard, and the keyboard includes a power input end and a power output end, characterized in that The hot-swap protection circuit includes: A first switch circuit, the input end of the first switch circuit is electrically connected to the power input end, and the output end of the first switch circuit is electrically connected to the power output end; A voltage sampling circuit, the sampling end of the voltage sampling circuit is electrically connected to the power input end, the controlled end of the first switch circuit is electrically connected to the output end of the voltage sampling circuit, and the voltage sampling circuit is used to detect the voltage of the power input end and output a corresponding voltage detection signal to control the conduction / turn-off of the first switch circuit; A current sampling circuit, the sampling end of the current sampling circuit is electrically connected to the power input end, and the current sampling circuit is used to sample the current of the power input end and output a corresponding current detection signal; A comparison circuit, the first input end of the comparison circuit is electrically connected to the output end of the current sampling circuit, the second input end of the comparison circuit is connected to a preset voltage value, and the output end of the comparison circuit is electrically connected to the controlled end of the first switch circuit. The comparison circuit is used to compare the magnitudes of the current detection signal and the preset voltage value and control the conduction / turn-off of the first switch circuit according to the comparison result.

2. The hot-swap protection circuit according to claim 1, wherein The voltage sampling circuit includes: A second switch circuit and a first voltage-dividing circuit. The input end and the controlled end of the second switch circuit are both electrically connected to the power input end. The output end of the second switch circuit and the output end of the comparison circuit are both electrically connected to the first end of the first voltage-dividing circuit. The second end of the first voltage-dividing circuit is electrically connected to the controlled end of the first switch circuit.

3. The hot plug protection circuit according to claim 2, characterized in that, The second switch circuit includes: A first zener diode, a second zener diode, a first resistor, a second resistor, a third resistor, and a first switching tube. The first end of the first resistor is electrically connected to the power input end. The second end of the first resistor is respectively connected to the first end of the second resistor and the cathode of the first zener diode. The anode of the first zener diode is grounded. The second end of the second resistor is respectively connected to the anode of the second zener diode and the controlled end of the first switching tube. The cathode of the second zener diode and the input end of the first switching tube are both electrically connected to the power input end. The output end of the first switching tube is respectively connected to the second end of the third resistor and the first end of the first voltage-dividing circuit. The first end of the third resistor is electrically connected to the power input end.

4. The hot-swap protection circuit according to claim 3, wherein The first voltage-dividing circuit includes: A fourth resistor and a fifth resistor. The first end of the fourth resistor is electrically connected to the controlled end of the first switch circuit. The second end of the fourth resistor is connected to the first end of the fifth resistor. The first end of the fifth resistor is also respectively connected to the output end of the comparison circuit and the output end of the first switching tube. The second end of the fifth resistor is grounded.

5. The hot-plug protection circuit according to claim 1, wherein The current sampling circuit includes: A third switching transistor, a fourth switching transistor, a fifth switching transistor, a first operational amplifier, and a sixth resistor. The input terminal of the third switching transistor is electrically connected to the power input terminal. The output terminal of the third switching transistor is electrically connected to the input terminal of the first switching circuit. The input terminal of the fourth switching transistor is electrically connected to the power input terminal. The control terminal of the fourth switching transistor is electrically connected to the control terminal of the third switching transistor. The output terminal of the fourth switching transistor is electrically connected to the input terminal of the fifth switching transistor. The output terminal of the fifth switching transistor is electrically connected to the first end of the sixth resistor. The second end of the sixth resistor is grounded. The first input terminal of the comparison circuit is electrically connected to the first end of the sixth resistor. The inverting terminal of the first operational amplifier is electrically connected to the output terminal of the third switching transistor. The non-inverting terminal of the first operational amplifier is electrically connected to the output terminal of the fourth switching transistor. The output terminal of the first operational amplifier is electrically connected to the control terminal of the fifth switching transistor.

6. The hot-swap protection circuit according to claim 1, characterized in that, The first switching circuit includes: A sixth switching transistor, a seventh resistor, and a first capacitor. The input terminal of the sixth switching transistor is electrically connected to the power input terminal. The output terminal of the sixth switching transistor is electrically connected to the power output terminal. The control terminal of the sixth switching transistor is electrically connected to the output terminals of the current sampling circuit and the voltage sampling circuit respectively. The first end of the first capacitor is electrically connected to the input terminal of the sixth switching transistor. The second end of the first capacitor is electrically connected to the control terminal of the sixth switching transistor. The first end of the seventh resistor is electrically connected to the control terminal of the sixth switching transistor. The second end of the seventh resistor is grounded.

7. The hot plug protection circuit according to claim 1, characterized in that, The hot-swap protection circuit further includes: An eighth resistor and a ninth resistor. The first end of the eighth resistor is electrically connected to the power output terminal. The second end of the eighth resistor is electrically connected to the first end of the ninth resistor. The second end of the ninth resistor is grounded.

8. The hot plug protection circuit according to claim 1, wherein, The keyboard further includes a plurality of signal transmission terminals. The hot-swap protection circuit further includes: A plurality of transient suppression diodes. The first ends of the plurality of transient suppression diodes are electrically connected to the power input terminal and the plurality of signal transmission terminals one by one. The second ends of the plurality of transient suppression diodes are all grounded.

9. A keyboard, characterized in that, Comprising the hot-swap protection circuit according to any one of claims 1 to 8.

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