Integrated circuit detection methods

Commonly used detection methods

Commonly used detection methods for integrated circuits include on-line measurement methods, off-line measurement methods, and substitution methods.

1. Off-Line Measurement Off-Line Measurements When the integrated circuit is not soldered into the circuit, it is determined by comparing the DC resistance between each pin and the DC resistance between pins of a known normal-type IC. Is it normal?

2. On-line measurement On-line measurement methods use voltage measurement, resistance measurement, and current measurement methods to determine if the integrated circuit is damaged by measuring the voltage, resistance, and current values ​​of each pin of the integrated circuit on the circuit.

3. Substitution method substitution method is to replace the tested integrated circuit with a well-known integrated circuit of the same model and same specification, and it can be judged whether the integrated circuit is damaged.

(b) Detection of commonly used integrated circuits

1. Detection of microprocessor integrated circuits The key test pins of the microprocessor integrated circuit are the VDD power supply terminal, the RESET reset terminal, the XIN crystal signal input terminal, the XOUT crystal signal output terminal, and other line input and output terminals. Measure the resistance and voltage values ​​of these critical feet to ground to see if they are the same as the normal values ​​(can be found in the product circuit diagram or related maintenance information). Different types of microprocessor RESET reset voltage is not the same, some low-level reset, that is, at the moment of boot is low, after the reset to maintain high; some are high reset, that is, at the moment of the switch is high, Keep low after reset.

2. Switching Power Supply Integrated Circuit Detection Switching Power Supply The critical voltages of an integrated circuit are the power supply (VCC), the excitation pulse output, the voltage detection input, and the current detection input. Measure the voltage and resistance of each pin to ground. If there is a large difference between them and the normal value, it can be determined that the integrated circuit is damaged if the peripheral components are normal. Built-in high-power switch tube thick film integrated circuit, but also by measuring the switch tube C, B, E between the positive and negative resistance, to determine whether the switch is normal.

3. Detection of Audio Amplifier Integrated Circuit When checking the audio amplifier integrated circuit, the voltage and resistance values ​​of the power supply terminals (positive power supply terminal and negative power supply terminal), audio input terminal, audio output terminal, and feedback terminal to ground should be detected first. If the measured data value of each pin differs greatly from the normal value, its peripheral components are normal, and the internal of the integrated circuit is damaged. For audio power integrated circuits that cause silent faults, when the power supply voltage is measured to be normal, signal interference can be used to check. When measuring, the multimeter should be placed in R×1, and the red meter should be grounded. Touch the audio input with a black meter. Normally, the speaker should have a strong “click”.

4. The operational amplifier integrated circuit detects the DC voltage level of the multimeter and measures the voltage between the output of the operational amplifier and the negative power supply (high in static voltage). With a hand-held metal tweezers, touch the two input terminals of the operational amplifier in order (add interference signals). If the multimeter has a large swing, then the operational amplifier is in good condition; if the multimeter is not moving, it indicates that the operational amplifier is damaged.

5. Time base integrated circuit detection Time base integrated circuit contains digital circuits and analog circuits, it is difficult to directly measure the quality of the use of multimeter. The test circuit shown in Figure 9-13 can be used to detect the quality of the time base integrated circuit. The test circuit consists of a RC component, a light-emitting diode LED, a 6V DC power supply, a power switch S, and an 8-pin IC socket. After inserting the time base integrated circuit (such as NE555) into the IC socket, press the power switch S. If the base integrated circuit is normal during the test, the light emitting diode LED will flash and emit light; if the LED is off or remains on, it indicates that the LED is being tested. Time base integrated circuit performance is poor.