Method for testing output locking or no-output fault of digital circuit

Abstract

The invention provides a method for testing a stuck-at fault or an open-circuit fault of a digital circuit. Output faults of the digital circuit can be diagnosed online according to the method, and the false alarm rate of a system is reduced. The method is implemented according to the following technical scheme: a latch 1 and a latch serially connected through a time delay device are electrically connected to two input ends of an XNOR comparator respectively; as for data signals outputted by a device of a digital circuit system at the current moment, the XNOR comparator firstly delays the inputted current data for a moment through a time delay and latch circuit formed by the latch 2 serially connected through a time delay circuit and then sends the delayed data to the latch 2 so as to be latched; and the XNOR comparator performs XNOR operation and comparison on latch data of the latch 2 at the previous moment and latch data of the latch 1 at the current output moment, and judging whether results of continuous and repeated comparisons are consistent or not, wherein if the results are not consistent, it is shown that circuit output is normal, if the results are consistent, it is shown that a stuck-at fault or an open-circuit fault occurs in output of the digital circuit. The method provided by the invention realizes online test and diagnosis for system faults of the digital circuit.

Description

technical field [0001] The invention belongs to the field of digital circuit fault testing, and more specifically relates to a testing method for a digital circuit output locked or no output fault mode. Background technique [0002] With the rapid development of digital circuits, the functions of digital circuits are becoming more and more complex, their performance is rapidly improving, and their applications are becoming more and more extensive. Digital circuits have become the core part of more and more electronic systems, and the failure of digital circuits will greatly affect the work of the system and become the main factor for the failure of the entire circuit. There are many kinds of digital circuits, the structure and function are becoming more and more complex, the scale and complexity of the circuit system are rising sharply, and the corresponding circuit maintenance work is also facing new difficulties. Digital circuit failure is caused by poor contact, damage t...

AI Technical Summary

Problems solved by technology

Due to the continuous use of electronic components, it will lead to aging and parameter performance degradation, and some of them change the parameter performance when the temperature changes

[0004] (2) Signal line failure

When the circuit board circuit is affected by the outside world, the signal line will be damaged and short circuit and open circuit will occur.

[0005] (3) Bad contact of circuit components

This kind of problem is the most common. If there is false welding or the solder joints are oxidized during work, it will lead to circuit board failure.

[0006] (4) Unhealthy working environment

Once the working environment does not meet the requirements of the equipment, such as humidity, temperature and electromagnetic environment, etc., the normal operation of the equipment cannot be realized

[0007] (5) Exceeded the period of use

[0012] The above four methods are conventional methods commonly used in the detection of digital circuit faults, but these methods use conventional instruments and traditional manual analysis, so the difficulty in diagnosis and positioning will increase and the cycle will become longer, resulting in the design and production of digital The speed of the circuit is seriously reduced, and it cannot be tested online.

[0013] In addition, on the basis of the above test methods, a digital circuit output function based on the IEEE Std 1149.1-2001 standard and a fault test method for interconnection between circuits have been developed. Although this method can test functions and interconnection faults, this method only supports some Integrated digital circuit testing with the standard

Most digital integrated circuits do not support this standard due to factors such as cost and function, so this type of digital circuit cannot use this standard for fault testing, and the test method based on this standard cannot effectively support online fault testing and diagnosis applications of digital circuits

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