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IC application circuit likened method
In the radio equipment, the application of more and more extensive integrated circuits, integrated circuit application circuit likened the circuit analysis a key one is difficult.
1. IC application circuit function
IC application circuit has the following features:
① It expresses the PIN IC detection tester for electronic circuit structure, component parameters, so that a complete work of integrated circuits.
② some IC application circuit, painted the IC's internal block diagram, application for analysis of integrated circuits is relatively easy circuit, but this kind of representation.
③ IC application circuit have typical application circuit and two practical circuits in integrated circuit, which can be found in the manual, which appear in practical circuit, the difference between the two application circuit, according to this characteristic, in the absence of practical application of circuit diagrams, typical application circuit diagram can be used for reference, the method used in repair.
④ application circuit generally integrated conveyed a complete circuit unit, or a circuit system, but in some cases a complete circuit system with two or more integrated circuits.
2. characteristics of IC application circuit
IC application circuit has the following features:
① most application circuit does not draw the internal block diagram, this negative on reading, especially for the beginner to circuit analysis is more detrimental to the work.
② for beginners, the analysis of the integrated circuit application circuit Analysis Division of the circuit components, this is more difficult for the IC's internal circuitry not understanding of original margin, actually read it, or repair or IC circuit than discrete components.
③ on IC application circuit, with an overview of IC's internal circuitry and learn more about the role of the PIN, is more convenient to read. This is because the same type of integrated circuits with regularity, in common with them, you can easily analyze many features of different models of IC application circuit.
3. application reading method IC circuit and cautions
Analysis methods and considerations of integrated circuits are the following:
(1) understanding of the role of the PIN is the key to understanding
Understanding the role of each pin can access to the relevant application manual for integrated circuits. Know the pin of the analysis the PIN after detection tester for electronic circuit working principle and the role of components. For example: know ① feet is the input pin, and the series of ① feet is the input coupling capacitance circuit, and connected to the circuit ① feet is input circuit.
(2) understanding of the role of each pin IC 3 methods
Understanding sets the internal block diagram analysis; the third is based on the IC application circuit characteristics in each pin detection tester for electronic circuit analysis. The third method requires a better circuit analysis. The role of the PIN into the circuit has three methods: first, access to such information; the second is based on integrated circuits
(3) circuit analysis steps
IC application circuit analysis steps are as follows:
① DC circuit analysis. This step is for the power supply and grounding pin detection tester for electronic circuit analysis. Note: power supply pin has more than one time to distinguish between the power relationship between, for example, if the fore, back-stage circuit power PIN, or left and right channel pins of power; on multiple earthing pin also to distinguish.
Distinguish between multiple power supply pins and earthing pin, it is useful to repair.
② signal transmission analysis. This step in the analysis of signal input pin or output pin detection tester for electronic circuit. When integrated with multiple input and output pins, to find out is before or after the level circuit output pin; dual-mono circuitry also distinguish between left and right channels of input and output pins.
③ other pin detection tester for electronic circuit analysis. For example, identify negative feedback pins, pins, etc., the Elimination of this step of the analysis is the most difficult for beginners, to help PIN function or the internal block diagram.
④ has a certain ability to read, to learn to summarize the various features of the integrated circuit pin detection tester for electronic circuit patterns and to master the law, to improve the reading speed is useful. For example, enter the PIN detection tester for electronic circuit rule is: via a coupling capacitance or a coupled circuit and the front-stage electric circuit is connected to the output-side; the output pin detection tester for electronic circuit rule is: via a coupling circuits and circuit is connected to the input side.
⑤ analysis IC incircuit on signal amplification, the processing procedure, the best is to have access to the internal block diagram of the integrated circuit. Analysis of the internal block diagram, you can signal transmission line arrow indicates, know what signal amplification or processing circuit, from which the final signal output pin.
⑥ understand some key IC test points, pin DC voltage regulation on maintenance of circuit is very useful. OTL circuit output DC voltage equal to IC DC voltage of half; OCL circuit outputs 0V DC voltage equal to; BTL circuit two output DC voltage is equal, single-supply operation is equal to half of the DC voltage, dual supply is equal to 0V. When integrated circuit between two pins with resistance, the resistance will affect both the DC voltage on PIN; when the two pins with coil between the two pins of the DC voltage is equal, not equal time will be open-coil; when between two pins with capacitance or RC series circuit, these two pin DC voltage must not equal to equal the capacitor has breakdown.
⑦ generally do not go to the analysis of the internal workings of integrated circuits, which is rather complex.