How to identify the quality of TVS transient suppression diodes?

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How to identify the quality of TVS transient suppression diodes?

Posted Date: 2024-02-06

How to identify the quality of TVS transient suppression diodes?

TVS transient suppression diode is an electronic device used to suppress transient voltage overshoot. It can protect other components in the circuit from damage by directing overvoltages to ground or other shunt conduits that accept voltages. Therefore, selecting and judging the quality of TVS diodes is crucial to protecting the circuit and enhancing its reliability. This article will introduce in detail how to identify the quality of TVS transient suppression diodes, including the following aspects: appearance, electrical characteristics testing, discharge capability testing, linear characteristics testing, etc.

First of all, appearance is an important indicator to judge the quality of TVS diodes. In terms of appearance, we can check from the following aspects:

1. Packaging: TVS diodes are usually packaged with the chip inside out to facilitate installation and soldering. We should pay attention to check whether the pads and pins are intact and there is nothing missing or damaged.

2. Appearance quality: The casing of TVS diodes is usually made of plastic or metal. We should inspect the casing for cracks, scratches, or other physical damage. In addition, we should also check whether the printed marks are clearly legible and there is no blur or uneven printing.

3. Package airtightness: Use a magnifying glass to carefully check whether the package has good airtightness. We should observe no bubbles, residue or other foreign matter inside the package. If bubbles, residue, or other foreign matter is present, it may indicate a failure in the production process or a defective packaging.

After completing the visual inspection, we also need to conduct a series of electrical characteristics tests.

1. Impedance measurement: The impedance of a TVS diode is one of its most basic electrical characteristics. We can measure its impedance using a multimeter or oscilloscope. Before testing, we should ensure that the test device and connecting cables are reliable. Measure the Zener resistance of the TVS diode through forward and reverse voltage chopping, and compare it with the value in the specification to determine the quality of the TVS diode.

2. Voltage measurement: By applying different voltages and observing the response of the TVS diode, its normal working status can be judged. We can gradually increase the voltage applied to the diode and monitor the relationship between current and voltage. If the current increases sharply or the voltage cannot continue to increase when the specified voltage is reached, it indicates that the TVS diode may be damaged.

3. Voltage withstand capability: TVS diodes are used to protect other electronic components from transient overvoltage. We can test a diode's voltage withstand capability by measuring its response by applying a transient high voltage that exceeds its rated operating voltage. If during the test, the TVS diode can respond quickly, shunt and keep the overvoltage within a safe range, it means that it has good transient suppression capabilities.

4. Linear characteristic test: We can observe its linear characteristics by connecting the TVS diode to a certain voltage and gradually increasing the current. If the response meets the parameters and curves on the data sheet, it indicates good linearity.

In addition, the discharge capacity is a very important indicator to judge the quality of TVS diodes.

Discharge capability test: The discharge capability of TVS diodes is measured by applying a transient high voltage greater than its rated operating voltage. A pulse generator can be used to generate a high voltage transient and an oscilloscope or start time and duration can be used to observe the response of the TVS diode. If the TVS diode can guide the overvoltage quickly and accurately and shunt it to ground or other paths that can accept the voltage, we can judge that its discharge capability is good.

Through inspection and testing in the above aspects, we can identify the quality of TVS transient suppression diodes. It should be noted that for different models and brands of TVS diodes, their characteristics and parameters may be different. Therefore, when judging its quality, we should refer to the corresponding specification book or data sheet to ensure that its actual performance meets the requirements.

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