What is an integrated circuit?
The integrated circuit is a kind of miniature electronic device. The integrated circuit manufacturing process is used to interconnect the numerous components and wiring that are required to be fabricated on a small piece of semiconductor wafer or dielectric substrate, and then packaged into a stand-alone device, a micro-structure with the desired circuit. It has the characteristics of small size, light weight, stable circuit and high integration, which is widely used in electronic products.
1.Classification of integrated circuits
There are many kinds of integrated circuits used in electrical appliances, which are traditionally divided into household appliances integrated circuits according to the function of integrated circuits, industrial and electrical integrated circuits, general purpose integrated circuits ( such as the basic gate circuits and operational amplifier IC in some general digital circuits) .
2. Identify the integrated circuit pins
The number of pins in the integrated circuit is different, some have 3~4 root pins, and some are as many as dozens to hundreds of pins. It is very important to identify the pins in the repair. In the principle diagram, only the pin sequence number of the integrated circuit is marked, for example, by reading the electrical schematic diagram, it is known that the foot is a negative feedback pin. To find the fifth foot in the object of the integrated circuit, the pin distribution of the integrated circuit is first understood. By the way, it is pointed out that the pins of different models are different, but the distribution rule of pins is the same.
The rule of pin distribution in integrated circuits can be divided into the following categories according to the different packaging and pin arrangement of IC.
( 1 ) The pins of the single in-line integrated circuit are arranged in a " _ " shape. Typically, there are special signs on the left side of the single in-line integrated circuit, in order to define the position of pin 1, which is marked with an arc notch, small missing angle, small color point, small circular hole and so on.
( 2 ) The pins of the dual-in-line integrated circuit are evenly distributed in two columns. Typically, the left side of the dual-in-line integrated circuit has a special flag to define the position of pin 1. Generally, the pin below the tag is 1, and the top of the tag is often the last pin. It has a small round pit, a small color point, a strip mark, a small semicircle gap and so on.
(3)Dome encapsulated integrated circuit using a metal shell, shaped like a transistor.
(4)The four column integrated circuit, , there is a mark on the integrated block, which indicates the location of pin 1, and then counts counter clockwise in turn.
(5)In some (few) integrated circuits, the distribution law of the reverse distribution integrated circuits is exactly the opposite of the distribution law mentioned above, and the reverse distribution law is adopted. The purpose of this is to make the integrated circuit easy to install on the reverse side of the circuit board.
The reverse distribution of the integrated circuit usually marks the letter R at the end of the model, and some more letters in the tail of the model than the forward distribution. For example, HA1368 is a forward distributed integrated circuit, its reverse distribution integrated circuit is HAl368R, the functions of the two integrated circuits, the number of pins, the internal circuit structure and so on, but the distribution of the pins is the opposite.
3.Detect an integrated circuit
In the detection, the integrated circuit detects the ground resistance and the supply voltage of the integrated circuit, and judges whether the integrated circuit is damaged according to the detection result. When the integrated circuit is damaged, it is generally necessary to replace the same type of integrated circuit. Some integrated circuits can also be repaired by external circuits according to the internal circuit data, but require the repairman to have a certain radio base.
The application of the integrated circuit, we should pay attention to the fact that the pin can not be connected to the wrong, and notice that the limit parameters can not be used beyond the limit; note that the temperature can not be too high when welding, and the pin can not be welded.