TL431 is an integrated circuit with voltage regulation characteristics, its working principle is to establish a constant voltage between the control pin (Cathode end) and the reference voltage (Anode end), so the method of judging TL431 is good or bad can usually be considered from the following aspects:
1. Test voltage: Establish a standard test voltage (usually 2.5V) between the control pin (Cathode end) and the reference voltage (Anode end) of the TL431. If it is difficult to establish a standard voltage, it may indicate that the TL431 is faulty.
2. Normal operating current: Use the normal operating current test to monitor the voltage to determine whether the TL431 can maintain its management voltage under normal operation. If the current is lower than the usual value (1-10 mA), it indicates that there may be a problem.
3. Reliable reverse protection: Test the reverse protection function, by reversely applying voltage between the pin and the reference end, you can confirm whether the reverse protection of the TL431 is normal.
4. Check the tempering voltage: the tempering voltage of TL431 usually needs to meet a certain standard, if the tempering voltage is unstable or does not meet the standard, it may indicate that the TL431 has been damaged.
In short, the above test methods need to be tested by professional testing tools or instruments to get accurate results. Therefore, it is suggested that in actual operation, you need to have a certain experimental experience and testing skills. If in doubt, it is recommended to seek the help of professional technicians.
The TL431 can be judged from the following aspects: It can be judged by the TL431 measurement results and performance parameters.
TL431 is a voltage reference that is commonly used as a reference for reference voltage sources and comparison levels in circuits.
Can be judged by measuring its reference voltage, temperature stability, linearity and other performance parameters.
If these performance parameters are good, it means that their quality is good. In addition, the TL431 can be judged by the actual use, such as its service life, stability and so on.
When purchasing or using TL431, it is also necessary to pay attention to its brand, batch number, use environment and other factors.
The key to judging the quality of TL431 is to test its electrical performance.
TL431 as a regulation device, mainly through its three characteristic parameters - stable voltage, reference current and dynamic resistance, to judge its performance.
In the test, TL431 can be connected to the standard test circuit, by measuring the value of its three characteristic parameters, to evaluate whether its performance meets the requirements.
In addition, TL431 can be tested for temperature and load changes to observe its stability and adaptability.
In general, only in TL431 three characteristic parameters and stability, adaptability and other performance meet the requirements of the premise, can be considered as a good TL431.
There are several ways to judge the TL431.
First of all, it can be determined whether there are defects or damage by checking its appearance quality.
Secondly, it can be tested for circuit connectivity and compliance with its specified parameter range by using a multimeter.
An oscilloscope can also be used to detect the stability and quality of its output waveform.
Finally, it can be applied to the actual circuit to observe the stability and reliability of the entire circuit. It is worth noting that the quality of TL431 not only depends on its quality, but also its use environment, application field and so on.
Therefore, these aspects need to be taken into account when conducting TL431 quality testing.
You can use the diode gear of the digital multimeter to measure, and the measurement steps are as follows.
The first step is: we first use the black pen to measure the anode A of the TL431, the red pen to measure its reference pole R, then the number should be shown is 1.4, and then switch the pen to display the number should be 1.3 this value.
The second step is: use the black watch pen to measure the anode A of the TL431, the red watch pen to measure its cathode K, then the number should be shown is 1, and then switch the watch pen to display the number should be 0.6.
The third step is: use the red watch pen to measure the TL431 reference pole R, the black watch pen to measure its cathode K, then the number should be shown is 0.7, and then switch the watch pen to display the number should be 1.
According to its internal function (SO-92 package is 1R, 2A, 3K), the good TL431 uses the diode file of the multimeter to measure R to K (more than 800), and the anti-detection is not possible; Measure A to K pass (more than 600), K to A pass; R to A through, A to R through (more than 800, the largest value). If it doesn't work, it could be overflow