Detection method of the hottest integrated circuit

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Detection methods of integrated circuits

(I) common detection methods

common detection methods of integrated circuits include measurement method, non measurement method and modern foreign products, and there are also many missing methods

1. non measurement non measurement tide when the integrated circuit is not soldered into the circuit, the DC resistance between its pins is measured internationally and compared with the DC resistance between the pins of the known normal integrated circuit of the same model to determine whether it is normal

2. measurement method is to use voltage measurement method, resistance measurement method and current measurement method to judge whether the integrated circuit is damaged by measuring whether the voltage value, resistance value and current value of each pin of the integrated circuit are normal on the circuit

3. substitution method substitution method is to replace the tested integrated circuit with a known intact integrated circuit of the same model and specification, which can judge whether the integrated circuit is damaged

(II) detection of common integrated circuits

1. Detection of microprocessor integrated circuits the key test pins of microprocessor integrated circuits are VDD power supply terminal, reset reset terminal, Xin crystal oscillator signal input terminal, xout crystal oscillator signal output terminal and other line input and output terminals. Measure the resistance and voltage of these key pins to the ground in the circuit to see whether they are the same as the normal value (which can be found out from the product circuit diagram or relevant maintenance information). The reset voltage of different types of microprocessors is also different. Some are low-level reset, that is, it is low level at the moment of startup, and it remains high level after reset; Some are high-level reset, that is, it is high level at the moment of switching, and maintain low level after reset

2. detection of switching power supply integrated circuit the key pin voltage of switching power supply integrated circuit is power supply terminal (VCC), excitation pulse output terminal, voltage detection input terminal and current detection input terminal. Measure the voltage value and resistance value of each pin to the ground. If there is a large difference from the normal value, under the condition that its peripheral components are normal, it can be determined that the integrated circuit has been damaged. The thick film integrated circuit with built-in high-power switch tube can also judge whether the switch tube is normal by measuring the forward and reverse resistance values between poles C, B and e of the switch tube

3. detection of audio power amplifier integrated circuit when checking the audio power amplifier integrated circuit, the voltage value and resistance value of its power end (positive power end and negative power end), audio input end, audio output end and feedback end to the ground should be detected first. If the measured data value of each pin is significantly different from the normal value, and its peripheral components are normal, it is the internal damage of the integrated circuit. When the power supply voltage of the audio power amplifier IC causing silent fault is measured to be normal, the signal interference method can be used to check it. When measuring, the multimeter should be placed in R × In gear 1, ground the red probe and touch the audio input end with the black probe. There should be a strong "click" sound in the speaker under normal conditions

4. Use the DC voltage range of the multimeter for the detection of the operational amplifier integrated circuit to measure the voltage value between the output end of the operational amplifier and the negative power supply end (the voltage value is high in static state). Using hand-held metal tweezers to touch the operational amplifier in turn is mainly to select the two inputs of the amplifier (add interference signals) from the material and structure of the fixture. If the multimeter needle swings greatly, it indicates that the operational amplifier is intact; If the multimeter needle does not move, the operational amplifier is damaged

5. Detection of time-based integrated circuits. Time-based integrated circuits contain digital circuits and analog circuits. It is difficult to directly measure their quality with a multimeter. The test circuit shown in the figure can be used to detect the quality of the time-based integrated circuit. The test circuit consists of resistance capacitance element, led, 6V DC power supply, power switch s and 8-pin I socket Xu Fei C, director of the Department of industry and information technology of Tibet Autonomous Region. After plugging the time-based integrated circuit (such as NE555) into the IC socket, press the power switch S. if the measured time-based integrated circuit is normal, the LED will flash; If the LED is not on or always on, it indicates that the performance of the time-based integrated circuit under test is poor. (end)

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