Frequently asked questions: What about chip failure?
Time:2020-03-04
Views:482
■ Logical function error We can regard all kinds of chips as a "black box" with certain functions, and we don‘t need to know much about the internal structure and working principle of this black box, as long as we know the corresponding logical relationship between its input signal and output signal. If the black box can‘t get the correct output result for the correct input signal, then this fault is called logic function fault or logic fault. The reasons for this failure may be the wrong components in the chip, the short circuit or open circuit of the wiring between components, and the disconnection between the internal logic circuit and the input and output pins of the chip. The logic fault of the chip is the most common chip fault, which is obvious and easy to check. ■ Chip breakdown Chip breakdown refers to the complete conduction between a pair or a group of input and output pins of the chip, and sometimes it shows that individual pins and multiple pins are directly connected with power pins or ground pins. After the chip breaks down, not only its own logic function is abnormal, but also its own input or output terminal is often fixed at a constant level, which makes the output of its superior chip have logic errors. This phenomenon often occurs in processor chips or bus driver chips with three-state input and output. The biggest feature of this kind of fault is short circuit, which can be checked by multimeter. ■ The driving ability of the chip is poor. In the circuit design, different interface chips should be used according to different interface requirements, and the number of chips driven by the output signals of the chips should be less than the allowable fan-out value. If the fan-out value of the chip can‘t meet the rated index, it will cause the system or a local circuit to work normally when there are few connected devices. With the increase of devices, the system will not work normally or even can‘t work at all. This kind of fault mostly occurs in I/O interface, so it is difficult to check with software or test instruments, so it is difficult to check and maintain.
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