A discrete quantity signal interface circuit

Abstract

The utility model belongs to the field of avionics technology, and provides a discrete signal interface circuit, including a filter circuit, a magnetic coupling isolator and an anti-jitter circuit, wherein the signal input end of the magnetic coupling isolator inputs a discrete signal through the filter circuit, and the discrete signal is input to the anti-jitter circuit through the magnetic coupling isolator, and then output through the anti-jitter circuit. The utility model can realize high-reliability access and high-speed real-time acquisition of discrete signals, reduce the area occupied by the interface circuit in the circuit board, and also ensure the normal operation of the product and the safety of the aircraft.

Description

Technical Field

[0001] The utility model belongs to the technical field of aviation electronics and relates to a discrete quantity signal interface circuit. Background Art

[0002] Discrete signal interface circuits are widely used in avionics products to collect discrete signals from aircraft. On the one hand, discrete signals participate in the logical processing of avionics products themselves, and the correct collection results are necessary to ensure the normal operation of the products; on the other hand, the access of discrete signals cannot cause interference to the aircraft and the equipment itself. Existing discrete signal interface circuits use optocouplers to isolate input signals from output signals, which have the following problems: high signal acquisition delay, high power consumption, and large size, especially when multiple inputs are performed, each input needs to be configured with a corresponding optocoupler. Utility Model Content

[0003] The purpose of the utility model is to solve the above-mentioned problems existing in the prior art and provide a discrete quantity signal interface circuit.

[0004] The utility model is realized through the following technical scheme: a discrete quantity signal interface circuit, including a filtering circuit, a magnetic coupling isolator and an anti-jitter circuit, the signal input end of the magnetic coupling isolator inputs the discrete quantity signal through the filtering circuit, the discrete quantity signal is input to the anti-jitter circuit through the magnetic coupling isolator, and then output through the anti-jitter circuit.

[0005] Furthermore, the signal output end of the filter circuit is connected to the signal input end of the magnetic coupling isolator through a pull-up circuit.

[0006] Furthermore, the magnetic coupling isolator is a magnetic coupling isolator with a voltage conversion function.

[0007] Furthermore, the magnetic coupling isolator is a multi-channel magnetic coupling isolator having at least two signal input terminals.

[0008] Furthermore, the model of the magnetic coupling isolator is BL7141WH or CA-IS3740HW.

[0009] Furthermore, the filtering circuit includes a common-mode inductor and a TVS tube; the front and rear ends of one coil in the common-mode inductor serve as the signal input end and output end of the filtering circuit respectively; the front and rear ends of another coil in the common-mode inductor are respectively connected to the signal ground; and the front ends of the two coils of the common-mode inductor are connected through the TVS tube.

[0010] Furthermore, the debouncing circuit is a Schmitt trigger.

[0011] Furthermore, the model of the Schmitt trigger is SGM7SZ14YC5G.

[0012] Furthermore, the pull-up circuit includes a power supply and a pull-up resistor, one end of the pull-up resistor is connected to the power supply, and the other end is connected to a node where the signal input end of the magnetic coupling isolator is connected to the signal output end of the filter circuit.

[0013] Furthermore, the pull-up circuit includes a power supply and pull-up resistors corresponding one to one with the signal input terminals of the magnetic coupling isolator; each pull-up resistor is provided with a corresponding filtering circuit; one end of each pull-up resistor is connected to the power supply, and the other end is connected to a node where the corresponding signal input terminal on the magnetic coupling isolator is connected to the signal output terminal of the corresponding filtering circuit.

[0014] Compared with the prior art, the beneficial effects of the utility model include:

[0015] 1. The prior art uses an optical coupler isolator to isolate input signals from output signals. Although it has good anti-interference performance, it has high delay, high power consumption, and large size. The utility model uses a magnetic coupling isolator to isolate input discrete signals from output discrete signals, which can reduce delay, reduce power consumption, and reduce the size of the interface circuit.

[0016] 2. The utility model sets a filter circuit at the front end of the magnetic coupling isolator, which can not only eliminate the external interference that may be coupled on the discrete signal input line, but also eliminate the electromagnetic interference of the magnetic coupling isolator in the discrete signal interface circuit outputted in reverse to the aircraft.

[0017] 3. The utility model adopts a de-jitter circuit to de-jitter the output signal of the magnetic coupling isolator before outputting it, which can ensure the reliability of triggering and avoid false triggering.

[0018] 4. In situations where multi-channel discrete signal acquisition is required, compared to using multiple optocoupler isolators, one magnetic coupler isolator can support multi-channel input, saving hardware costs and reducing the volume of discrete signal interface circuits.

[0019] 5. The utility model can realize high-reliability access and high-speed real-time acquisition of multi-channel discrete quantity signals, reduce the area occupied by the interface circuit in the circuit board, and ensure the normal operation of the product and the safety of the aircraft. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a circuit block diagram of a discrete quantity signal interface circuit in this specific implementation mode;

[0021] Figure 2 It is a circuit schematic diagram of the discrete quantity signal interface circuit in this specific implementation manner. DETAILED DESCRIPTION

[0022] The utility model is described in further detail below in conjunction with the accompanying drawings.

[0023] The existing discrete signal interface circuit uses an optocoupler isolator to isolate the input signal from the output signal, which has the following problems: high signal acquisition delay, high power consumption, and large size. Especially when multiple inputs are performed, each input needs to be configured with a corresponding optocoupler isolator.

[0024] In order to collect discrete quantity signals in a timely and reliable manner, refer to Figure 1 As shown, the utility model provides a discrete quantity signal interface circuit, including a filter circuit 1, a magnetic coupling isolator 2 and an anti-jitter circuit 3. The signal input end of the magnetic coupling isolator 2 inputs the discrete quantity signal through the filter circuit 1, and the discrete quantity signal is input to the anti-jitter circuit 3 through the magnetic coupling isolator 2, and then output through the anti-jitter circuit 3.

[0025] Example 1

[0026] refer to Figure 2 As shown, in this embodiment, the filter circuit includes a common-mode inductor T1 and a TVS tube V1, and the TVS tube is also called a transient voltage suppressor diode (Transient Voltage Suppressor); the front and rear ends of one coil in the common-mode inductor T1 are respectively used as the signal input end and the output end of the filter circuit; the front and rear ends of the other coil in the common-mode inductor T1 are respectively connected to the signal ground; the front ends of the two coils of the common-mode inductor are connected through the TVS tube V1.

[0027] Discrete signal from Figure 2 The left-center CH3 input passes through the filter circuit composed of TVS tube V1 and common mode inductor T1 in parallel. When there is surge voltage or interference, it will be introduced to the ground.

[0028] When a surge voltage occurs, the TVS tube changes from a high-resistance state to a low-resistance state, directing the surge voltage into the ground, thereby protecting the subsequent circuits.

[0029] When the signal is normal, the TVS tube is in the off state, and the normal signal enters the common-mode inductor, which on the one hand filters out common-mode interference, and on the other hand suppresses the electromagnetic interference emitted by the product itself, especially the electromagnetic interference output by the magnetic coupling isolator to the aircraft in reverse.

[0030] Example 2

[0031] This embodiment is used to collect multi-channel discrete quantity signals and output them to the FPGA chip. Specifically, based on Example 1, the magnetic coupling isolator is a multi-channel magnetic coupling isolator having at least two signal input terminals and a voltage conversion function, for example, a magnetic coupling isolator of model BL7141WH or CA-IS3740HW.

[0032] The signal output end of the filter circuit is connected to the signal input end of the magnetic coupling isolator through a pull-up circuit. When the discrete quantity is an "on" signal (i.e., the input end is suspended), the pull-up circuit can clamp the output signal of the filter circuit at a high level to ensure signal stability and improve anti-electromagnetic interference performance.

[0033] refer to Figure 2 As shown, in this embodiment, the pull-up circuit includes a 5V power supply and pull-up resistors R1, R2, and R3 corresponding to the signal input terminals of the magnetic coupling isolator U1; each pull-up resistor is provided with a corresponding filter circuit (in order to simplify the drawings, only the filter circuit composed of the common-mode inductor T1 and the TVS tube v1 is shown in the figure); one end of each pull-up resistor is connected to the 5V power supply, and the other end is connected to the node where the corresponding signal input terminals VIC, VIB, and VIA on the magnetic coupling isolator are connected to the signal output terminal of the corresponding filter circuit.

[0034] This embodiment uses a Schmitt trigger as a de-jitter circuit. The signal output by the magnetic coupling isolator U1 enters the Schmitt trigger U2 (for example, a Schmitt trigger of model SGM7SZ14YC5G), and is output to the FPGA chip after shaping and de-jittering. This embodiment uses a Schmitt trigger as a de-jitter circuit. Compared with the use of relays or digital de-jittering, it can reduce the delay. The combination of the Schmitt trigger and the magnetic coupling isolator can further reduce the delay, shorten the sampling interval, and improve the sampling efficiency.

[0035] A corresponding Schmitt trigger is provided for each signal output end of the magnetic coupling isolator to meet the requirements of multi-channel input and multi-channel output.

[0036] When the input discrete quantity signal is a ground level signal, the input of the magnetic coupling isolator is at the ground level, there is no current on the input side of the magnetic coupling isolator, no magnetic field is generated, and there is no "magnetic generation of electricity" process on the output side, that is, there is no change on the output side, so the magnetic coupling isolator outputs a low level. When the input discrete quantity signal is an open signal, the input of the magnetic coupling isolator is pulled up to 5V by the pull-up circuit. In the magnetic coupling isolator U1, the signal is magnetically isolated and converted to a 3.3V high level output to the corresponding Schmitt trigger.

[0037] In addition, the 5V power supply powers the magnetic coupling isolator through its power pin EN1, and the magnetic coupling isolator converts the 5V voltage into a 3.3V voltage and powers the Schmitt trigger through its power pin EN2, thereby achieving power sharing and reducing the size of the discrete signal interface circuit.

[0038] Example 3

[0039] This embodiment is used for single-channel discrete quantity signal acquisition. The only difference between this embodiment and Embodiment 2 is that: the magnetic coupling isolator is a single-channel magnetic coupling isolator with a voltage conversion function; the pull-up circuit includes a power supply and a pull-up resistor, one end of the pull-up resistor is connected to the power supply, and the other end is connected to a node where the signal input end of the magnetic coupling isolator is connected to the signal output end of the filter circuit.

[0040] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0041] The above technical scheme is only a specific implementation method of the utility model. For those skilled in the art, it is easy to make various types of improvements or modifications based on the principles disclosed in the utility model, and it is not limited to the technical scheme described in the above specific embodiments of the utility model. Therefore, the above description is only preferred and does not have a restrictive meaning.

Claims

1. A discrete quantity signal interface circuit, characterized in that: It includes a filtering circuit, a magnetic coupling isolator and an anti-jitter circuit. The signal input end of the magnetic coupling isolator inputs a discrete quantity signal through the filtering circuit, the discrete quantity signal is input to the anti-jitter circuit through the magnetic coupling isolator, and then output through the anti-jitter circuit.

2. The discrete quantity signal interface circuit according to claim 1, characterized in that: The signal output end of the filter circuit is connected to the signal input end of the magnetic coupling isolator through a pull-up circuit.

3. The discrete quantity signal interface circuit according to claim 1, characterized in that: The magnetic coupling isolator is a magnetic coupling isolator with a voltage conversion function.

4. The discrete quantity signal interface circuit according to claim 3, characterized in that: The magnetic coupling isolator is a multi-channel magnetic coupling isolator having at least two signal input terminals.

5. The discrete quantity signal interface circuit according to claim 4, characterized in that: The model of the magnetic coupling isolator is BL7141WH or CA-IS3740HW.

6. The discrete quantity signal interface circuit according to claim 2, characterized in that: The filter circuit includes a common-mode inductor and a TVS tube; the front and rear ends of one coil in the common-mode inductor serve as the signal input end and output end of the filter circuit respectively; the front and rear ends of another coil in the common-mode inductor are respectively connected to the signal ground; the front ends of the two coils of the common-mode inductor are connected through the TVS tube.

7. The discrete quantity signal interface circuit according to claim 1, characterized in that: The debouncing circuit is a Schmitt trigger.

8. The discrete quantity signal interface circuit according to claim 7, characterized in that: The model of the Schmitt trigger is SGM7SZ14YC5G.

9. The discrete quantity signal interface circuit according to claim 2, characterized in that: The pull-up circuit includes a power supply and a pull-up resistor, one end of the pull-up resistor is connected to the power supply, and the other end is connected to a node where the signal input end of the magnetic coupling isolator and the signal output end of the filter circuit are connected.

10. The discrete quantity signal interface circuit according to claim 2, characterized in that: The pull-up circuit includes a power supply and pull-up resistors corresponding to the signal input terminals of the magnetic coupling isolator one by one; each pull-up resistor is provided with a corresponding filtering circuit; one end of each pull-up resistor is connected to the power supply, and the other end is connected to a node where the corresponding signal input terminal on the magnetic coupling isolator is connected to the signal output terminal of the corresponding filtering circuit.

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