What you must know about the inspection and substitution of integrated circuits
There are some knowledge about integrated circuit board circuits, which you must know. This knowledge mainly includes integrated circuit testing and integrated circuit replacement. We will separately explain in detail below. The detection of integrated circuits can use the following methods to detect whether the integrated circuit is normal: Logic analysis method The so-called logic analysis method means that if a certain integrated circuit is suspected of problems, first measure whether the input signal of the integrated circuit is normal, and then measure the integration Whether the output signal of the circuit is normal, if there is input but no output, it can generally be judged that the integrated circuit is damaged. DC resistance comparison method The DC resistance comparison method compares the DC resistance value of each pin of the integrated circuit to be detected with the DC resistance value of the normal integrated circuit to judge the quality of the integrated circuit. When measuring, use the same multimeter and the same electrical barrier to reduce measurement errors. The DC resistance comparison method can test integrated circuits of different models and structures, but normal integrated circuits of the same model must be used as a reference. Elimination method The elimination method means that if a certain part of the circuit (including the integrated circuit) is judged to be faulty during maintenance, the discrete components of this part of the circuit can be checked first. If the discrete components are normal, it means that the integrated circuit is faulty, and you should consider replacing the integrated circuit. Circuit. This method does not require integrated circuit reference materials, and does not need to understand the internal working principle of the circuit, so this method is widely used in the maintenance of liquid crystal displays. DC voltage measurement method The DC voltage measurement method is a common method for detecting integrated circuits. It mainly measures the DC working voltage value of each pin of the integrated circuit to the ground and compares it with the nominal value to judge the quality of the integrated circuit. Replacement of integrated circuits The inside of an integrated circuit is basically all semiconductors, which are tens of thousands of transistors assembled into a small device. Also because of this, there are many integrated circuits that can be replaced with each other, provided that their pins have the same function, the same working voltage, and the voltage of each pin is also the same, generally they can be used interchangeably (for MCU and memory, The internal procedures are also required to be the same). This feature is very useful for the replacement of some integrated circuits that are not available on the market or are overpriced. In addition, the quality of integrated circuits differs from place of origin. Imported products are of the best quality, followed by joint venture products. In the past period of time, domestically produced products were poor, so their prices are also very different. However, in recent years, the quality of domestic products has been greatly improved, while the price increase has not been large, which makes domestic products more competitive.