Improved structure of discrete magnitude signal power-on self-test circuit

Abstract

A discrete magnitude signal power-on self-test circuit improved structure disclosed by the present invention comprises an optical coupler, a first MOS transistor and a second MOS transistor, the source side of the optical coupler inputs a BIT signal, the output ends of the first MOS transistor and the second MOS transistor output an excitation signal or an output ground signal, the seven pins of the optical coupler are directly grounded GNDBIT through a resistor R3, and the resistor R3 is connected with the GNDBIT. Six pins of the optical coupler are connected into a VDDBIT used as a discrete magnitude signal excitation source, when a power-on self-test BIT signal is input into a low level, the optical coupler is conducted, a grid electrode of a first MOS tube is grounded and conducted to output an excitation signal for self-test, or a grid electrode of a second MOS tube is connected with a power supply and conducted to output a ground signal for self-test; according to the invention, general conventional low-cost devices are adopted, power-on self-test can be carried out on a large number of discrete magnitude signals without time sequence requirements, the number of excitation self-test channels is large, the cost of power-on self-test is greatly reduced, and the power-on self-test method is suitable for power-on self-test scenes in which aviation airborne equipment needs to carry out discrete magnitude signals.

Description

Technical Field

[0001] This invention relates to the field of power-on self-test circuit technology for discrete signals, specifically an improved structure for a power-on self-test circuit for discrete signals. Background Technology

[0002] With the deepening development of aviation electrification, the control logic of onboard systems has become more diverse and complex, and the design of airborne equipment has also become more complex. Onboard systems often contain many discrete signals, some of which cannot be periodically detected and can only be self-tested upon power-up. Common discrete signal power-up self-test circuits usually use multi-to-one analog switch chips or multiple optocoupler chips to inject excitation into different discrete signals, which is relatively expensive, has a limited number of channels, and occupies many I / O interfaces of control chips. Therefore, an improved structure for discrete signal power-up self-test circuits is proposed. Summary of the Invention

[0003] The purpose of this invention is to provide an improved structure for a discrete signal power-on self-test circuit, in order to solve the problems of relatively high cost and limited number of channels in existing power-on self-test circuits mentioned in the background art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: an improved structure for a discrete signal power-on self-test circuit, comprising an optocoupler, a first MOSFET, and a second MOSFET. The source side of the optocoupler receives a BIT signal. Eight pins of the optocoupler are connected to the gate of the first MOSFET, and five pins of the optocoupler are connected to the gate of the second MOSFET. The first and second MOSFETs output either an excitation signal or ground signals BIT_Signal_1-BIT_Signal_10. The outputs of the first and second MOSFETs are connected to diodes for isolating different discrete signals. The seven pins of the optocoupler are directly grounded to GND_BIT through resistor R3. The six pins of the optocoupler are connected to VDD_BIT, which is used as the excitation source for discrete signals. When the power-on self-test BIT signal input is low, the optocoupler is turned on. The gate of the first MOS transistor is grounded and turned on to output an excitation signal for self-test, or the gate of the second MOS transistor is connected to the power supply and turned on to output a ground signal for self-test.

[0005] Preferably, the first MOSFET is a P-channel field-effect transistor, and a resistor R1 is connected between the gate and drain of the first MOSFET, and the common terminal of the drain of the first MOSFET and the resistor R1 is connected to VDD_BIT.

[0006] Preferably, the second MOS transistor is an N-channel field-effect transistor, and a resistor R5 is connected between the gate of the second MOS transistor and the optocoupler, and a resistor R6 is connected between the source and the gate of the second MOS transistor.

[0007] Preferably, the two pins of the optocoupler are connected to the operating voltage VDD through resistor R2, and the three pins of the optocoupler are connected to the operating voltage VDD through resistor R4. When the optocoupler is turned on, the input current is 5-20mA.

[0008] The beneficial effects of this invention are: The circuit structure of this invention is simple, using common and low-cost first MOSFET, second MOSFET, optocoupler and diode devices. It can perform power-on self-test on a large number of discrete signals without timing requirements. It has a large number of excitation self-test channels, which reduces the cost of power-on self-test circuit for discrete signals. It is suitable for scenarios where airborne equipment needs to perform power-on self-test on discrete signals. Attached Figure Description

[0009] Figure 1 This is the power-on self-test circuit diagram for this invention.

[0010] In the diagram: 1. Optocoupler; 2. First MOSFET; 3. Second MOSFET; 4. Diode. Detailed Implementation

[0011] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0012] Please see Figure 1This invention provides a technical solution: an improved structure for a power-on self-test circuit for discrete signals, comprising an optocoupler 1, a first MOSFET 2, and a second MOSFET 3. The source side of the optocoupler 1 receives a BIT signal. Eight pins of the optocoupler 1 are connected to the gate of the first MOSFET 2, and five pins of the optocoupler 1 are connected to the gate of the second MOSFET 3. The output terminals of the first MOSFET 2 and the second MOSFET 3 output either an excitation signal or ground signals BIT_Signal_1-BIT_Signal_10. Diodes 4 for isolating different discrete signals are connected to the output terminals of the first MOSFET 2 and the second MOSFET 3. Seven pins of the optocoupler 1 are directly grounded to GND_BIT via a resistor R3. Pin 1 is connected to VDD_BIT, which is used as the excitation source for discrete signals. When the BIT signal input is low during power-on self-test, optocoupler 1 is turned on, the gate of the first MOSFET 2 is grounded and turned on to output an excitation signal for self-test, or the gate of the second MOSFET 3 is connected to the power supply and turned on to output a ground signal for self-test. It should be noted that the BIT signal needs to be output using a bus driver or other driver chip / circuit. The power-on self-test circuit for discrete signals has an improved structure, and the discrete excitation signal used has no timing requirements. Among them, there are ten groups of diodes 4, which are labeled D1-D10, BIT_Signal_1-BIT_Signal_10 respectively. Each group of diodes 4 corresponds to one group of BIT_Signal.

[0013] In this embodiment, the first MOSFET 2 is a P-channel MOSFET. A resistor R1 is connected between the gate and drain of the first MOSFET 2, and the common terminal of the drain of the first MOSFET 2 and the resistor R1 is connected to VDD_BIT. The second MOSFET 3 is an N-channel MOSFET. A resistor R5 is connected between the gate of the second MOSFET 3 and the optocoupler 1, and a resistor R6 is connected between the source and gate of the second MOSFET 3. The two pins of the optocoupler 1 are connected to the operating voltage VDD through a resistor R2, and the three pins of the optocoupler 1 are connected to the operating voltage VDD through a resistor R4. When the optocoupler 1 is turned on, the input current is 5-20mA, which can be adjusted according to the selected optocoupler 1 model and the source-side power supply size of the optocoupler 1. Preferably, the input current of the optocoupler 1 is 10mA. The optocoupler 1 adopts, but is not limited to, PC817, 4N25, TLP551, PC818 or LTV817 type optocouplers.

[0014] The improved structure of the discrete signal power-on self-test circuit performs a power-on self-test on the "VDD_BIT / On" signal. Under normal circumstances, the BIT signal is in a high-impedance state, optocoupler 1 is not conducting, the first MOSFET 2 is not conducting, and there is no output of the BIT_Signal_1-BIT_Signal_5 signals. At this time, there is no excitation injection for the discrete signal. When performing a power-on self-test, the BIT signal input is low, optocoupler 1 is conducting, the gate of the first MOSFET 2 is grounded, the gate-source voltage is less than the turn-on threshold, the first MOSFET 2 is conducting, and the output VDD_BIT voltage value of the BIT_Signal_1-BIT_Signal_5 signals needs to be reduced by the voltage drop of diode 4 to obtain the output excitation signal for self-test. When performing a power-on self-test with the "GND / ON" signal, under normal circumstances, the BIT signal is in a high-impedance state, optocoupler 1 is not conducting, the second MOSFET 3 is not conducting, and there is no output of the BIT_Signal_6-BIT_Signal_10 signals. At this time, there is no excitation injection of discrete signals. When performing a power-on self-test, the BIT signal input is low, optocoupler 1 is conducting, the gate of the second MOSFET 3 is connected to the power supply, the gate-source voltage is greater than the turn-on threshold, the second MOSFET 3 is conducting, and the BIT_Signal_6-BIT_Signal_10 signals are grounded, that is, the output ground signal is used for self-test.

[0015] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0016] The above embodiments only illustrate preferred embodiments of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be understood that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. In the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," "fixing," etc., should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can refer to a mechanical connection; it can refer to a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication of two components or the interaction between two components. Among these, there are various ways of detachable installation, such as by using a combination of plug-in and snap-fit, or by using bolt connections, etc.

[0017] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An improved structure for a power-on self-test circuit for discrete signals, characterized in that: The device includes an optocoupler, a first MOSFET, and a second MOSFET. The source side of the optocoupler receives a bit signal. Eight pins of the optocoupler are connected to the gate of the first MOSFET, and five pins of the optocoupler are connected to the gate of the second MOSFET. The first and second MOSFETs output either an excitation signal or ground signals BIT_Signal_1-BIT_Signal_10. The outputs of the first and second MOSFETs are connected to diodes for isolating different discrete signals. The seven pins of the optocoupler are directly grounded to GND_BIT through resistor R3. The six pins of the optocoupler are connected to VDD_BIT, which is used as the excitation source for discrete signals. When the power-on self-test BIT signal input is low, the optocoupler is turned on. The gate of the first MOS transistor is grounded and turned on to output an excitation signal for self-test, or the gate of the second MOS transistor is connected to the power supply and turned on to output a ground signal for self-test.

2. The improved structure of the power-on self-test circuit for discrete signals according to claim 1, characterized in that: The first MOSFET is a P-channel field-effect transistor. A resistor R1 is connected between the gate and drain of the first MOSFET, and the common terminal of the drain of the first MOSFET and the resistor R1 is connected to VDD_BIT.

3. The improved structure of the power-on self-test circuit for discrete signals according to claim 1, characterized in that: The second MOSFET is an N-channel field-effect transistor. A resistor R5 is connected between the gate of the second MOSFET and the optocoupler, and a resistor R6 is connected between the source and the gate of the second MOSFET.

4. The improved structure of the power-on self-test circuit for discrete signals according to claim 1, characterized in that: The two pins of the optocoupler are connected to the operating voltage VDD through resistor R2, and the three pins of the optocoupler are connected to the operating voltage VDD through resistor R4. When the optocoupler is turned on, the input current is 5-20mA.

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