A bidirectional high-speed pulse input circuit and device with current limiting protection function

Abstract

The present invention discloses a bidirectional high-speed pulse input circuit and device with a current-limiting protection function, including: a pre-stage anti-interference rectifier bridge circuit for receiving source-type or sink-type high-speed pulse signals and rectifying the received high-speed pulse signals; a high-speed optocoupler isolation acquisition and transmission circuit connected to the pre-stage anti-interference rectifier bridge circuit for acquiring external high-speed pulse signals, converting them into current signals, and performing shunt processing on the current signals; a current-limiting protection circuit for performing current-limiting protection on the overall circuit when an external high-level high-speed pulse signal is input; and a post-stage level comparator circuit connected to the high-speed optocoupler isolation acquisition and transmission circuit for shaping, filtering, and outputting the high-speed pulse signals, solving the defect that the existing digital input circuit cannot acquire bidirectional high-speed pulse signals, having current-limiting protection and strong anti-interference ability, and realizing more complex industrial field requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of sampling circuits, and particularly to a bidirectional high-speed pulse input circuit and device with a current-limiting protection function. Background Art

[0002] In common industrial control, for the control and protection of digital switching quantities and pulse quantity signals, means such as adding fuses and thermistors in series in the input channel are adopted. If they fail, they need to be replaced, which is very troublesome for on-site control replacement and maintenance. Especially when there are multiple points and multiple channels for input, there will be a large amount of heat loss, and current-limiting protection for multiple channels is very important. The requirements of conventional industrial sites include both source-type access and sink-type access. Conventional bidirectional optocoupler isolators can only collect and transmit low-speed pulse signals.

[0003] A patent with the publication number CN205788001U and the name of an overcurrent protection circuit for a digital input loop proposes an overcurrent protection circuit for a digital input loop, providing a triode protection circuit directly connected in front of the digital input loop. Its defect is that the current-limiting resistor connected in series in the channel will cause voltage division and affect the signal input threshold standard required by the actual site, and it can only access unidirectional signals, without solving the problem that both source-type and sink-type can be accessed.

[0004] A patent with the publication number CN209545415U and the name of a wide-voltage digital input interface circuit proposes a wide-voltage digital input interface circuit. Its defect is that the circuit has an obvious shortcoming of being unable to distinguish the high and low states of the voltage of ordinary digital quantity signals input in industry, and the PLC cannot achieve logical control, and it is even more unable to collect high-speed pulse signals.

[0005] A patent with the publication number CN216596001U and the name of a digital input circuit and device proposes a digital input circuit and device. Its defect is that it only provides a method for limiting the loop current. There are trigger inverters and shift register components in the subsequent circuit. One is that the use cost is higher, and the other is that there is a level delay, and it is also unable to collect high-speed pulse signals.

[0006] Combining the above-mentioned disadvantages and considerations, it is necessary to propose a design scheme for collecting and transmitting high-speed pulse signals, which can be effectively applied to the current-limiting protection of multiple channels when transmitting high levels, and the signals are not lost when transmitting high-speed pulse signals, ensuring signal quality. Summary of the Invention

[0007] The purpose of the present invention is to provide a bidirectional high-speed pulse input circuit and device with a current-limiting protection function, which solves the defect that the existing digital input circuit cannot collect bidirectional high-speed pulse signals, and has current-limiting protection and strong anti-interference ability, realizing more complex industrial site requirements.

[0008] The present invention provides a bidirectional high-speed pulse input circuit with a current limiting protection function, including a front-stage anti-interference rectifier bridge circuit, a high-speed optocoupler isolation acquisition and transmission circuit, a current limiting protection circuit, and a rear-stage level comparator circuit;

[0009] The front-stage anti-interference rectifier bridge circuit is used to receive a source-type or sink-type high-speed pulse signal, rectify the received high-speed pulse signal to obtain a stable DC wave signal;

[0010] The high-speed optocoupler isolation acquisition and transmission circuit is connected to the front-stage anti-interference rectifier bridge circuit, and is used to collect an external high-speed pulse signal and convert it into a current signal, and perform a shunt process on the current signal;

[0011] The current limiting protection circuit is connected to the front-stage anti-interference rectifier bridge circuit and the high-speed optocoupler isolation acquisition and transmission circuit, and is used to perform current limiting protection on the overall circuit when an external high-level high-speed pulse signal is input;

[0012] The rear-stage level comparator circuit is connected to the high-speed optocoupler isolation acquisition and transmission circuit, and is used to shape and filter the high-speed pulse signal output by the high-speed optocoupler isolation acquisition and transmission circuit and output it.

[0013] Preferably, the front-stage anti-interference rectifier bridge circuit includes a TVS diode and a general rectifier bridge. The two ends of the TVS diode are respectively connected to the two ends of the AC input terminal of the rectifier bridge. The positive pole of the DC output terminal of the rectifier bridge is connected to the input terminal of the high-speed optocoupler isolation acquisition and transmission circuit, and the negative pole of the DC output terminal of the rectifier bridge is connected to the current limiting protection circuit.

[0014] Preferably, the high-speed optocoupler isolation acquisition and transmission circuit includes a high-speed optocoupler U1, a current limiting resistor R1, a shunt resistor R3, a sampling resistor R6, and a resistor R7; one end of the current limiting resistor R1 is connected to the output terminal of the front-stage anti-interference rectifier bridge circuit, and the high-speed pulse signal output by the front-stage anti-interference rectifier bridge circuit passes through the current limiting resistor R1 to generate a current signal; the other end of the current limiting resistor R1 is divided into two paths. One path passes through the shunt resistor R3 and is connected to one input terminal of the high-speed optocoupler U1, and the other path is directly connected to the other input terminal of the high-speed optocoupler U1. One output terminal of the high-speed optocoupler U1 is grounded, and the other output terminal of the high-speed optocoupler U1 is connected to one end of the sampling resistor R6 and connected to the power supply Vdd, and the other output terminal of the high-speed optocoupler U1 is connected to the resistor R7 and connected to the rear-stage level comparator circuit.

[0015] Preferably, by controlling the magnitude of the current Id flowing through the input side of the high-speed optocoupler U1, the magnitude of the current I1 on the output side of the high-speed optocoupler is controlled; wherein, the corresponding relationship between the magnitudes of Id and I1 is determined by the characteristics of the high-speed optocoupler U1 itself, and the magnitude of the level input to the positive input terminal of the subsequent level comparator circuit is V1 = Vdd - I1 * R6; when the level Vpi of the input high-speed pulse signal is greater than or equal to the preset high-level threshold, after the level signal is shunted by the current-limiting resistor R1, it is ensured that the current flowing through the input side of the high-speed optocoupler U1 is sufficient to turn on the optocoupler without damage, completing the protection of the input high-voltage signal circuit; when the level Vpi of the input high-speed pulse signal is less than or equal to the preset low-level threshold, after being shunted by the current-limiting resistor R1, it is ensured that the current flowing through the input side of the high-speed optocoupler U1 is not sufficient to turn on the optocoupler, completing the filtering of low-voltage clutter. Among them, the input threshold requirements for high and low levels of digital input are achieved by adjusting the resistance values of the current-limiting resistor R1, the shunt resistor R3, and the sampling resistor R6.

[0016] Preferably, the current-limiting protection circuit includes a resistor R2, a resistor R4, a resistor R5, a resistor R, a triode Q1, and a triode Q2. The collector of the triode Q1 is connected to the high-speed optocoupler isolation acquisition and transmission circuit. The base of the triode Q1 is connected to one end of the resistor R2. The other end of the resistor R2 is respectively connected to the high-speed optocoupler isolation acquisition and transmission circuit and the front-stage anti-interference rectifier bridge circuit. One end of the resistor R2 is connected to the collector of the triode Q2. The emitter of the triode Q2 is connected to the series-connected resistor R and resistor R5 and then connected to the emitter of the triode Q1. The base of the triode Q2 is connected to the parallel-connected capacitor C1 and resistor R4 and then connected to the base of the triode Q1.

[0017] Preferably, when the input signal level is greater than the level threshold, Ub1 of the triode Q1 > Ue1, then the triode Q1 conducts, and the triode Q1 is in a saturated state;

[0018] When the voltage is transmitted to the base of the triode Q2, Ub2 > Ue2, then the triode Q2 conducts. As the signal level increases, when the triode Q2 changes from the amplification state to the saturated state, when the triode Q2 enters the saturated state, the voltage U2be across the base and emitter of the triode Q2 approaches 0.6 - 0.7V;

[0019] When the externally input signal level is greater than the preset value, the current flowing through the main circuit of the circuit is limited to U2be / R;

[0020] Among them, the current flowing through the triode Q1 is the sum of the currents flowing through the resistor R3 and the input side of the high-speed optocoupler U1; the current flowing through the resistor R is I = U2be / R, which is approximately equal to the current flowing through the emitter-collector of the triode Q1, that is, the sum of the currents flowing through R3 and the input side of the high-speed optocoupler U1. Ub1 refers to the voltage between the base and emitter of the triode Q1, Ue1 refers to the voltage between the emitter of the triode Q1 and the ground or reference point, Ub2 refers to the voltage between the base and emitter of the triode Q2, Ue2 refers to the voltage between the emitter of the triode Q2 and the ground or reference point, and U2be refers to the voltage difference between the base and emitter of the triode Q2, that is, the difference between Ub2 and Ue2.

[0021] Preferably, the post-stage level comparator circuit includes a resistor R8, a resistor R9, a resistor R10, and a comparator U2. The positive input terminal of the comparator U2 is connected to the level V1 output by the high-speed optocoupler isolation transmission acquisition circuit, and the positive input terminal of the comparator U2 is connected to the output terminal of the comparator U2 through the resistor R10. The negative input terminal of the comparator U2 is connected to the series-connected resistor R8 and resistor R9. The output terminal of the comparator U2 outputs a logic level signal for comparing the level V1 output by the high-speed optocoupler isolation transmission acquisition circuit obtained through the positive input terminal of the comparator U2 with the reference level Vref at the negative input terminal of the comparator U2. Among them, the reference level Vref = Vdd*R9 / (R8 + R9).

[0022] Preferably, when the level output by the high-speed optocoupler isolation transmission acquisition circuit is greater than the reference level, the output terminal of the comparator U2 outputs a high logic level; when the level output by the high-speed optocoupler isolation transmission acquisition circuit is less than the reference level, the output terminal of the comparator U2 outputs a low logic level.

[0023] The present invention also provides a bidirectional high-speed pulse input device with a current limiting protection function, and the device includes a bidirectional high-speed pulse input circuit with a current limiting protection function as described in the embodiment of the present invention.

[0024] The present invention also provides a control system, and the control system includes a bidirectional high-speed pulse input circuit with a current limiting protection function as described in the embodiment of the present invention.

[0025] Aiming at the prior art, the present invention has the following beneficial effects:

[0026] The present invention discloses a bidirectional high-speed pulse input circuit and device with a current limiting protection function, including: a pre-stage anti-interference rectifier bridge circuit, a current limiting protection circuit, a high-speed optocoupler isolation acquisition and transmission circuit, and a post-stage level comparator circuit. The pre-stage anti-interference rectifier bridge circuit receives a source-type or sink-type high-speed pulse signal, performs rectification processing, and outputs a signal. The input end of the high-speed optocoupler isolation acquisition and transmission circuit is connected to the output end of the pre-stage anti-interference rectifier bridge circuit. The high-speed optocoupler isolation acquisition and transmission circuit acquires an external high-speed pulse signal, converts it into a current signal, and performs shunt processing on the current signal. The current limiting protection circuit is connected to the pre-stage anti-interference rectifier bridge circuit and the high-speed optocoupler isolation acquisition and transmission circuit, and plays a role in current limiting protection for the overall circuit when an external high-level high-speed pulse signal is input. The input end of the post-stage level comparator circuit is connected to the output end of the high-speed optocoupler isolation acquisition and transmission circuit, and is used to shape and filter the high-speed pulse signal output by the high-speed optocoupler isolation acquisition and transmission circuit and output it, solving the defect that the existing digital input circuit cannot acquire bidirectional high-speed pulse signals, and having current limiting protection and strong anti-interference ability, and realizing more complex industrial field requirements.

[0027] The present invention can acquire and transmit high-speed pulse signals up to 200KHZ, and the signal quality is complete. It can meet the two wiring access methods of source type and sink type in the industrial field, and has strong anti-interference and current limiting protection capabilities in multi-channel input applications. The components are simple and universal, and the use cost is low, which well realizes the domestic automation and independent control requirements of PLC products in the field of high-frequency pulse quantity input acquisition and control. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the bidirectional high-speed pulse input circuit with a current limiting protection function described in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0030] In the actual implementation of this embodiment, it is assumed that the level of the input high-speed pulse signal is Vpi. According to the industrial standard GBT15969 of programmable controllers and actual requirements, when Vpi ≥ 4V, it is recognized as a high level by the subsequent digital control circuit, and the signal logic is "1". When Vpi ≤ 1V, it is recognized as a low level by the subsequent digital control circuit, and the signal logic is "0". Among them, PLC: Programmable Logic Controller, a digital computing operation electronic system specially designed for application in industrial environments. It uses a programmable memory to store instructions for performing operations such as logical operations, sequential control, timing, counting, and arithmetic operations internally, and controls various types of mechanical equipment or production processes through digital or analog inputs and outputs. High-speed pulse input: The process of inputting very fast pulse signals into a PLC (Programmable Logic Controller) through external sensors or devices; the PLC accurately captures these pulse signals and converts them into data that can be used for control. Digital quantity: Also called logical quantity, it has only two value ranges, namely 0 or 1, on or off. Pulse quantity: A digital quantity whose value is always constantly alternating between 0 (low level) and 1 (high level). The number of times the pulse alternates per second is called the frequency.

[0031] As Figure 1 shown, the present invention provides a bidirectional high-speed pulse input circuit with a current-limiting protection function, applicable to a PLC controller, including a pre-stage anti-interference rectifier bridge circuit, a high-speed optocoupler isolation acquisition and transmission circuit, a current-limiting protection circuit, and a post-stage level comparator circuit; the pre-stage anti-interference rectifier bridge circuit is used to receive a source-type or sink-type high-speed pulse signal, rectify the received high-speed pulse signal to obtain a stable DC wave signal; the high-speed optocoupler isolation acquisition and transmission circuit is connected to the pre-stage anti-interference rectifier bridge circuit, used to collect an external high-speed pulse signal and convert it into a current signal, and perform shunt processing on the current signal; the current-limiting protection circuit is connected to the pre-stage anti-interference rectifier bridge circuit and the high-speed optocoupler isolation acquisition and transmission circuit, used to perform current-limiting protection on the overall circuit when an external high-level high-speed pulse signal is input; the post-stage level comparator circuit is connected to the high-speed optocoupler isolation acquisition and transmission circuit, used to shape and filter the high-speed pulse signal output by the high-speed optocoupler isolation acquisition and transmission circuit and output it, solving the defect that the existing digital input circuit cannot collect bidirectional high-speed pulse signals, and having current-limiting protection and strong anti-interference ability, meeting the more complex industrial field requirements.

[0032] Specifically, the pre-stage anti-interference rectifier bridge circuit includes a TVS diode and a general-purpose rectifier bridge, which are used for rectifying complex industrial field signals to obtain a stable DC wave signal, compatible with two input methods of high-speed pulse signal source type input and sink type input, and also having a protection function to prevent high voltage from damaging the device port. Both ends of the TVS diode are respectively connected to both ends of the AC input terminal of the rectifier bridge, the positive pole of the DC output terminal of the rectifier bridge is connected to the input terminal of the high-speed optocoupler isolation acquisition and transmission circuit, and the negative pole of the DC output terminal of the rectifier bridge is connected to the current limiting protection circuit.

[0033] Specifically, the high-speed optocoupler isolation acquisition and transmission circuit includes a general-purpose unidirectional high-speed optocoupler U1, a current-limiting resistor R1, a shunt resistor R3, a sampling resistor R6, and a resistor R7. One end of the current-limiting resistor R1 is connected to the output end of the front-stage anti-interference rectifier bridge circuit, and the high-speed pulse signal output by the front-stage anti-interference rectifier bridge circuit generates a current signal after passing through the current-limiting resistor R1. The other end of the current-limiting resistor R1 is divided into two paths. One path is connected to an input terminal of the high-speed optocoupler U1 through the shunt resistor R3, and the other path is directly connected to the other input terminal of the high-speed optocoupler U1. One output terminal of the high-speed optocoupler U1 is grounded, and the other output terminal of the high-speed optocoupler U1 is connected to one end of the sampling resistor R6 and connected to the power supply Vdd, and the other output terminal of the high-speed optocoupler U1 is connected to the resistor R7 and connected to the rear-stage level comparator circuit. The principle is as follows: By controlling the magnitude of the current Id flowing through the input side of the high-speed optocoupler U1, the magnitude of the current I1 on the output side of the high-speed optocoupler can be controlled. It can be understood that when the high-speed pulse signal output by the front-stage anti-interference rectifier bridge circuit generates a current signal after passing through R1, a part of the current flows through the input side of the high-speed optocoupler U1, and the other part flows through R3. By controlling the magnitude of the current Id flowing through the input side of the high-speed optocoupler, the magnitude of the current I1 on the output side of the high-speed optocoupler can be controlled. Among them, the corresponding relationship between the magnitudes of Id and I1 is determined by the characteristics of the high-speed optocoupler U1 itself. The magnitude of the level input to the positive input terminal of the rear-stage level comparator circuit is V1 = Vdd - I1 * R6. When the level Vpi of the input high-speed pulse signal is greater than or equal to the preset high-level threshold, such as 4V, after the level signal is shunted by the current-limiting resistor R1, it is ensured that the current flowing through the input side of the high-speed optocoupler U1 is sufficient to turn on the optocoupler without damage, completing the protection function for the input high-voltage signal circuit. When the level Vpi of the input high-speed pulse signal is less than or equal to the preset low-level threshold, such as 1V, after being shunted by the current-limiting resistor R1, it is ensured that the current flowing through the input side of the high-speed optocoupler U1 is not sufficient to turn on the optocoupler, completing the filtering function for low-voltage clutter. Among them, by adjusting the resistance values of the current-limiting resistor R1, the shunt resistor R3, and the sampling resistor R6, the input threshold requirements for the high and low levels of the digital input can be achieved. That is, in actual use, according to the input threshold requirements of the digital input logic "1" and logic "0" required by the industry, the resistance values of the three general-purpose resistors R1, R3, and R6 can be adjusted to achieve this.

[0034] Specifically, the current limiting protection circuit includes resistor R2, resistor R4, resistor R5, resistor R, triode Q1 and triode Q2. Among them, Q1 is the main circuit power triode and must be selected with a large package and high power. Q2 is a general-purpose triode. The collector of the triode Q1 is connected to the high-speed optocoupler isolation acquisition and transmission circuit. The base of the triode Q1 is connected to one end of the resistor R2. The other end of the resistor R2 is respectively connected to the high-speed optocoupler isolation acquisition and transmission circuit and the pre-stage anti-interference rectifier bridge circuit. One end of the resistor R2 is connected to the collector of the triode Q2. The emitter of the triode Q2 is connected to the series-connected resistor R and resistor R5 and then connected to the emitter of the triode Q1. The base of the triode Q2 is connected to the parallel-connected capacitor C1 and resistor R4 and then connected to the base of the triode Q1.

[0035] In the above current limiting protection circuit, with the input of the high-speed pulse signal output by the pre-stage anti-interference rectifier bridge circuit, a part of the current of the entire circuit loop will be divided in this part of the circuit. The current flowing through Q1 is the sum of the current flowing through the R3 resistor and the input side of the high-speed optocoupler. When the input signal level is greater than the level threshold, Ub1>Ue1 of the triode Q1, then the triode Q1 conducts and the triode Q1 is in the saturation state. When the voltage is transmitted to the base of the triode Q2, Ub2>Ue2, then the Q2 triode conducts. As the signal level increases, when the triode Q2 changes from the amplification state to the saturation state, when the triode Q2 enters the saturation state, the voltage U2be between the base and emitter of the triode Q2 approaches 0.6 - 0.7V. When the externally input signal level is greater than the preset value, the current flowing through the main circuit of the circuit is limited to U2be / R. Among them, the current flowing through the resistor R is I = U2be / R, which is approximately equal to the current flowing through the emitter and collector of the triode Q1, that is, the sum of the current flowing through R3 and the input side of the high-speed optocoupler U1. Ub1 refers to the voltage between the base and emitter of the triode Q1, Ue1 refers to the voltage between the emitter of the triode Q1 and the ground or reference point, Ub2 refers to the voltage between the base and emitter of the triode Q2, Ue2 refers to the voltage between the emitter of the triode Q2 and the ground or reference point, and U2be refers to the voltage difference between the base and emitter of the triode Q2, that is, the difference between Ub2 and Ue2.

[0036] Specifically, the post-stage level comparator circuit includes a resistor R8, a resistor R9, a resistor R10, and a comparator U2. Due to the discrete distribution characteristics of the transmission ratio CTR parameter of the high-speed optocoupler itself, in the actual application of multi-channel digital quantity input, to expand the threshold voltage threshold window, increase the certainty of the logic level, and reduce the risk of false triggering, a level comparator is adopted. The level V1 output by the high-speed optocoupler isolation transmission acquisition circuit can be isolated by the level comparator. The positive input terminal of the comparator U2 is connected to the level V1 output by the high-speed optocoupler isolation transmission acquisition circuit, and the positive input terminal of the comparator U2 is connected to the output terminal of the comparator U2 through the resistor R10. The negative input terminal of the comparator U2 is connected to the series-connected resistors R8 and R9. The output terminal of the comparator U2 outputs a logic level signal, which is used to compare the level V1 output by the high-speed optocoupler isolation transmission acquisition circuit obtained through the positive input terminal of the comparator U2 with the reference level Vref at the negative input terminal of the comparator U2. Among them, the reference level Vref = Vdd * R9 / (R8 + R9).

[0037] During implementation, when the level output by the high-speed optocoupler isolation transmission acquisition circuit is greater than the reference level, the output terminal of the comparator U2 outputs a high logic level; when the level output by the high-speed optocoupler isolation transmission acquisition circuit is less than the reference level, the output terminal of the comparator U2 outputs a low logic level.

[0038] During implementation, in combination with the accompanying drawings, it is specifically described as follows:

[0039] When the input signal voltage is within the logic "1" range and an external high-speed pulse signal is input, after passing through the anti-interference rectifier bridge circuit, when the external voltage is abnormally large and exceeds the preset threshold, the current flowing through the Q1 triode increases, the current flowing through the resistor R increases, and the voltage across R increases. That is, the voltage across the base and emitter of Q2 increases, and the conduction degree of Q2 increases. At this time, Q2 operates in the amplification state, and the voltage difference between the emitter and collector of Q2 decreases, the base voltage of Q1 decreases, and the conduction degree of Q1 decreases. Then the current flowing through Q1 decreases, that is, the current flowing through R and the diode on the input side of the optocoupler decreases, maintaining the circuit in a dynamic balance process. When the external voltage increases within the design requirement standard, the current flowing through Q2 is large enough, and Q2 changes from the amplification state to the saturation state. At this time, the current flowing through the main circuit of R and Q1 remains constant, approximately I = U2be / R; when the input signal voltage is within the logic "0" range, the main circuit current is shunted by D1, and the current flowing through R1 is shunted by the resistor R3, and the current flowing through the input side of the high-speed optocoupler is not enough to conduct. The level on the output side of the high-speed optocoupler is processed by the subsequent comparator level circuit and then sent to the digital control processor to realize the recognition of the high and low levels of logic "1" and "0". Since the actual industrial field environment is relatively complex during use, abnormal situations such as excessive access levels are likely to occur. Therefore, this solution can well solve the problem of collecting bidirectional high-speed pulse signals and also takes into account the function of circuit protection when a higher level conducts.

[0040] The present invention also provides a bidirectional high-speed pulse input device with a current limiting protection function, and the device includes a bidirectional high-speed pulse input circuit with a current limiting protection function as described in the embodiment of the present invention.

[0041] The present invention also provides a control system, and the control system includes a bidirectional high-speed pulse input circuit with a current limiting protection function as described in the embodiment of the present invention.

[0042] The functional principle is as described in the above embodiments of the present invention and will not be elaborated here. For the parts not described in detail in the device, equipment or system embodiments, reference may be made to the relevant parts in the circuit embodiments.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A bidirectional high-speed pulse input circuit with a current limiting protection function, characterized in that, It includes a pre-stage anti-interference rectifier bridge circuit, a high-speed optocoupler isolation acquisition and transmission circuit, a current limiting protection circuit, and a post-stage level comparator circuit; The pre-stage anti-interference rectifier bridge circuit is used to receive a source-type or sink-type high-speed pulse signal, rectify the received high-speed pulse signal, and obtain a stable DC wave signal; The high-speed optocoupler isolation acquisition and transmission circuit is connected to the pre-stage anti-interference rectifier bridge circuit, and is used to collect an external high-speed pulse signal, convert it into a current signal, and perform a shunt process on the current signal; The current limiting protection circuit is connected to the pre-stage anti-interference rectifier bridge circuit and the high-speed optocoupler isolation acquisition and transmission circuit, and is used to perform current limiting protection on the overall circuit when an external high-level high-speed pulse signal is input; The post-stage level comparator circuit is connected to the high-speed optocoupler isolation acquisition and transmission circuit, and is used to shape and filter the high-speed pulse signal output by the high-speed optocoupler isolation acquisition and transmission circuit and output it; The pre-stage anti-interference rectifier bridge circuit includes a TVS diode and a general rectifier bridge. Two ends of the TVS diode are respectively connected to two ends of the AC input terminal of the rectifier bridge. The positive pole of the DC output terminal of the rectifier bridge is connected to the input terminal of the high-speed optocoupler isolation acquisition and transmission circuit, and the negative pole of the DC output terminal of the rectifier bridge is connected to the current limiting protection circuit; The high-speed optocoupler isolation acquisition and transmission circuit includes a high-speed optocoupler U1, a current limiting resistor R1, a shunt resistor R3, a sampling resistor R6, and a resistor R7; One end of the current limiting resistor R1 is connected to the output terminal of the pre-stage anti-interference rectifier bridge circuit. The high-speed pulse signal output by the pre-stage anti-interference rectifier bridge circuit generates a current signal after passing through the current limiting resistor R1. The other end of the current limiting resistor R1 is divided into two paths. One path passes through the shunt resistor R3 and is connected to one input terminal of the high-speed optocoupler U1, and the other path is directly connected to the other input terminal of the high-speed optocoupler U1. One output terminal of the high-speed optocoupler U1 is grounded, and the other output terminal of the high-speed optocoupler U1 is connected to one end of the sampling resistor R6 and connected to the power supply Vdd, and the other output terminal of the high-speed optocoupler U1 is connected to the resistor R7 and connected to the post-stage level comparator circuit; The current limiting protection circuit includes a resistor R2, a resistor R4, a resistor R5, a resistor R, a triode Q1, and a triode Q2. The collector of the triode Q1 is connected to the high-speed optocoupler isolation acquisition and transmission circuit. The base of the triode Q1 is connected to one end of the resistor R2. The other end of the resistor R2 is respectively connected to the high-speed optocoupler isolation acquisition and transmission circuit and the pre-stage anti-interference rectifier bridge circuit. One end of the resistor R2 is connected to the collector of the triode Q2. The emitter of the triode Q2 is connected to the resistor R and the resistor R5 connected in series and connected to the emitter of the triode Q1. The base of the triode Q2 is connected to the capacitor C1 and the resistor R4 connected in parallel and connected to the base of the triode Q1.

2. The two-way high-speed pulse input circuit with a current limiting protection function according to claim 1, wherein By controlling the magnitude of the current Id flowing through the input side of the high-speed optocoupler U1, the magnitude of the current I1 on the output side of the high-speed optocoupler is thus controlled; Among them, the size correspondence between Id and I1 is determined by the characteristics of the high-speed optocoupler U1 itself. The level of the forward input terminal of the subsequent level comparator circuit is V1 = Vdd - I1 * R6 after input; When the level Vpi of the input high-speed pulse signal is ≥ the preset high-level threshold, after the level signal is shunted by the current-limiting resistor R1, it is ensured that the current flowing through the input side of the high-speed optocoupler U1 is sufficient to turn on the optocoupler without damage, completing the protection function for the input high-voltage signal circuit; When the level Vpi of the input high-speed pulse signal is ≤ the preset low-level threshold, after being shunted by the current-limiting resistor R1, it is ensured that the current flowing through the input side of the high-speed optocoupler U1 is not sufficient to turn on the optocoupler, completing the filtering function for low-voltage noise, Among them, the input threshold requirements for the high level and low level of the digital input are achieved by adjusting the resistance values of the current-limiting resistor R1, the shunt resistor R3, and the sampling resistor R6.

3. A bidirectional high-speed pulse input circuit with a current-limiting protection function as described in claim 1, characterized in that When the input signal level is greater than the level threshold, Ub1 > Ue1 of the triode Q1, then the triode Q1 conducts, and the triode Q1 is in the saturation state; When the voltage is transmitted to the base of the triode Q2, Ub2 > Ue2, then the triode Q2 conducts. As the signal level increases, when the triode Q2 changes from the amplification state to the saturation state, when the triode Q2 enters the saturation state, the voltage U2be across the base and emitter of the triode Q2 approaches 0.6 - 0.7V; When the externally input signal level is greater than the preset value, the current flowing through the main circuit of the circuit is limited to U2be / R; Among them, the current flowing through the triode Q1 is the sum of the current flowing through the resistor R3 and the input side of the high-speed optocoupler U1; the current flowing through the resistor R is I = U2be / R, which is approximately equal to the current flowing through the emitter and collector of the triode Q1, that is, the sum of the current flowing through the resistor R3 and the input side of the high-speed optocoupler U1. Ub1 refers to the voltage between the base and emitter of the triode Q1, Ue1 refers to the voltage between the emitter of the triode Q1 and the ground or reference point, Ub2 refers to the voltage between the base and emitter of the triode Q2, Ue2 refers to the voltage between the emitter of the triode Q2 and the ground or reference point, and U2be refers to the voltage difference between the base and emitter of the triode Q2, that is, the difference between Ub2 and Ue2.

4. The bidirectional high-speed pulse input circuit with a current limiting protection function according to claim 1, wherein The subsequent level comparator circuit includes a resistor R8, a resistor R9, a resistor R10, and a comparator U2. The positive input terminal of the comparator U2 is connected to the level V1 output by the high-speed optocoupler isolation transmission acquisition circuit, and the positive input terminal of the comparator U2 is connected to the output terminal of the comparator U2 through the resistor R10. The negative input terminal of the comparator U2 is connected to the serially connected resistor R8 and resistor R9. The output terminal of the comparator U2 outputs a logic level signal for comparing the level V1 output by the high-speed optocoupler isolation transmission acquisition circuit obtained through the positive input terminal of the comparator U2 with the reference level Vref at the negative input terminal of the comparator U2. Among them, the reference level Vref = Vdd * R9 / (R8 + R9).

5. The bidirectional high-speed pulse input circuit with a current limiting protection function according to claim 4, characterized in that, When the level output by the high-speed optocoupler isolation transmission acquisition circuit is greater than the reference level, the output terminal of the comparator U2 outputs a high logic level; when the level output by the high-speed optocoupler isolation transmission acquisition circuit is less than the reference level, the output terminal of the comparator U2 outputs a low logic level.

6. A bidirectional high-speed pulse input device with a current limiting protection function, characterized in that, The device includes the bidirectional high-speed pulse input circuit with current limiting protection function as described in any one of claims 1 to 5.

7. A control system, characterized in that, The control system includes the bidirectional high-speed pulse input circuit with current limiting protection function as described in any one of claims 1 to 5.

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