Test methods and key points of integrated circuit comprehensive performance

Date：2021-12-28 13:50:00 Views：1696

From the initial model of an electronic product to the hands of consumers, an important thing related to whether the electronic product can leave the factory is to see whether the electronic product can pass the test of reliability test equipment. All products must have a certificate before they can be sold to consumers. If electronic products want to get a certificate, they must pass the test of reliability test equipment. The working principle of this reliability test equipment is to simulate the working environment of electronic products and make these electronic products work in different environments, such as high temperature and high humidity, To test the working ability of these electronic products to withstand high temperature and humidity. Through the detection of these reliability test equipment, we can know the weak shortcomings of this type of electronic products and help provide the functions of the electronic products.

1、 Judging the quality of digital integrated circuits by voltage method

1. If the power supply voltage of the digital integrated circuit is normal, the welding is good, and the measured voltage of its power pin is too low, it can be determined that the measured digital integrated circuit is damaged.

2. If the measured voltage value of the power supply voltage pin of the digital integrated circuit is normal, but most of the voltage values of other pins are abnormal, it indicates that the grounding pin is faulty welding, and most of the integrated circuit is normal.

3. If the measured voltage value of individual or a few pins of the digital integrated circuit deviates greatly from the normal value, check whether the original peripheral component circuit corresponding to this pin is faulty, such as resistance short circuit, open circuit, capacitor leakage or breakdown. If there is no fault in the peripheral component circuit, it indicates that the digital integrated circuit under test has been damaged.

4. If the measured voltage values of most pins of the digital integrated circuit deviate from the normal value more, and the power supply voltage is normal, and the power supply and grounding pins are not soldered, it can be determined that the digital integrated circuit has been damaged.

2、 Detection of TTL circuit quality and performance

Carefully observe the model of TTL integrated circuit, find the relevant data manual, find out the grounding terminal of the integrated circuit, and it is best to find its internal circuit diagram or wiring diagram.

Turn the selection switch of the multimeter to R × 1K gear, the black probe receives the grounding terminal of the integrated circuit, and the red probe successively tests the DC resistance value of each input terminal and output terminal to the ground. Under normal conditions, the resistance to ground of each pin of the integrated circuit shall be 3 ~ 10K Ω. If the resistance of a pin to ground is less than 1 K Ω or greater than 12 K Ω, the integrated circuit has been damaged.

Connect the red pen of the multimeter to the ground, and use the black pen to test each input terminal and output terminal of the integrated circuit in turn. Under normal conditions, the reverse resistance of each end to the ground shall be greater than 40 K Ω. The resistance to ground of each pin of the damaged integrated circuit is less than 1 K Ω. For the positive and negative power supply pins of normal ttlt circuit, the forward resistance and reverse resistance are smaller than those of other pins to ground, and the maximum resistance is no more than 10 K Ω. If the value is zero or infinity, the power pin of the integrated circuit is damaged.

3、 Voltage method to distinguish TTL circuit from CMOS circuit

According to their models, cc4000, cd4006 and mc14021 belong to CMOS circuits, while ct3020 and 74 series belong to TTL circuits.

According to its power supply voltage, without knowing the model of digital integrated circuit, if it can work normally under the voltage of 3 ~ 4.5V or 5.5 ~ 18V, it can be sure that it is a CMOS circuit. The output level of the integrated circuit can also be tested with a multimeter. When the power supply voltage is 5V, connect the input terminal of the circuit to the high level and low level, and then test the output terminal with a multimeter. If the difference between the high and low levels is close to 5V, it is a CMOS integrated circuit; If it is close to 3.5V, it is TTL integrated circuit.

Distinguish according to the voltage value of its output level: take the simplest gate circuit as an example, the power supply voltage is 5V, the multimeter is placed in the DC voltage 10V, the input terminal of the integrated circuit is connected to the high and low levels in turn, and the voltage values corresponding to the high and low levels of its output terminal are measured respectively. If the difference between them is close to 5V, it is a CMOS circuit; If the difference between them is close to 3.5V, it is a TTL circuit.

4、 Distinguish CMOS circuits from high-speed CMOS circuits

Since the power supply voltage of CMOS circuit is 3 ~ 18V, and the power supply voltage of high-speed CMOS circuit is 2 ~ 6V, when the voltage of 2 ~ 2.5V is added to the integrated circuit, if the integrated circuit works normally, it indicates that the integrated circuit is a high-speed CMOS circuit, otherwise, the integrated circuit is a CMOS circuit.

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