What is the selection method and calculation process of ESD tube? Which forum friend can write out the calculation steps?

QWE4562009

What is the selection method and calculation process of ESD tube? Which forum friend can write out the calculation steps? [Copy link]

 

What is the selection method and calculation process of ESD tube? Which forum friend can write out the calculation steps?

chunyang

There is no such thing as an ESD tube. The tube mentioned in the original poster's post is called a bidirectional TVS tube.

qwqwqw2088

Anti-static diode ESD, no calculation

That is the working voltage (VRWM) and the breakdown voltage (VBR)

The principle is that the working voltage of the ESD device (VRWM) should be greater than the working voltage of the selected ESD in the circuit location.

For example, if the system voltage is 0~5V, you should choose a tube with a working voltage (VRWM) greater than 5V.

qwqwqw2088

ESD should also be divided into unidirectional or bidirectional ESD devices

QWE4562009

qwqwqw2088 Published on 2020-4-27 16:28 ESD diodes, there is no calculation except the working voltage (VRWM) and the breakdown voltage (VBR). The principle is that the working voltage (V ...

Is it enough to just focus on the working voltage? What is the appropriate breakdown voltage? Is it to short-circuit the input part after breakdown to prevent the high voltage from breaking down the subsequent components?

QWE4562009

qwqwqw2088 posted on 2020-4-27 16:28 ESD should also be divided into unidirectional or bidirectional ESD devices

The contacts are all bidirectional. Shouldn't it be similar to the reverse breakdown of the voltage regulator? Why is it bidirectional? I don't understand. Doesn't high voltage have only one direction?

qwqwqw2088

QWE4562009 posted on 2020-4-28 14:07 The contacts are all bidirectional. Shouldn't it be similar to the reverse breakdown of the voltage regulator? Why is it bidirectional? I don't understand. Doesn't high voltage only have one direction...

Bidirectional ESD devices can pass signals with positive and negative breakdown voltages (VBR), while unidirectional ESD devices can only pass signals with positive breakdown voltage (VBR). If a negative voltage is passed, the ESD device will break down.

maychang

QWE4562009 posted on 2020-4-28 14:07 The contacts are all bidirectional. Shouldn't it be similar to the reverse breakdown of the voltage regulator? Why is it bidirectional? I don't understand. Doesn't high voltage only have one direction...

When two Zener diodes are connected in reverse series, their voltage-current characteristic curve is the same as the first building, which is what you call "bidirectional".

QWE4562009

qwqwqw2088 posted on 2020-4-28 14:24 Bidirectional ESD devices can pass signals with positive and negative breakdown voltages (VBR), while unidirectional ESD devices can only pass signals with positive breakdown voltages (VBR). If...

That is to say, high voltage may appear at either the positive or negative pole. Can I understand it this way?

QWE4562009

qwqwqw2088 Published on 2020-4-27 16:28 ESD diodes, there is no calculation except the working voltage (VRWM) and the breakdown voltage (VBR). The principle is that the working voltage (V ...

What about the breakdown voltage?

qwqwqw2088

QWE4562009 posted on 2020-4-30 10:22 What about the breakdown voltage?

QWE4562009

qwqwqw2088 posted on 2020-4-30 11:25

Working voltage is 3-4V and breakdown voltage is 6-7V? Is ESD the same as a voltage regulator? It can only work in the breakdown state?

Is this simulation software or a data sheet?

qwqwqw2088

QWE4562009 Published on 2020-5-6 09:40 Working voltage 3-4V Breakdown voltage 6-7V? Is ESD the same as the voltage regulator? It can only work in the breakdown state? You...

TVS, ESD and Zener diodes are similar in principle and are all applied in reverse

The difference should be in terms of instantaneous response time, power consumption, etc. There is a lot of information on the Internet.

qwqwqw2088

qwqwqw2088 Published on 2020-5-6 11:43 TVS, ESD and Zener diodes are the same in principle, and are all reversely applied. The difference should be in the instantaneous response time, power consumption and other aspects. There is a lot of information on the Internet. ...

This curve is not difficult to find in the ESD manual

For example, ON Semiconductor's ESD8472

baron159

Working voltage, residual voltage, capacitance and other parameters

langtuodianzi

The first step to correctly select a TVS is to study the breakdown voltage (VBR). For example, if the maximum working voltage VRWM of the protected I/O line is 5V, the TVS should not enter its breakdown region before reaching this maximum voltage. Usually, the TVS product manual will include the VRWM of the specific leakage current, which makes it easier for us to choose the right TVS. Otherwise, we can choose a TVS with a VBR(min) that is a few volts greater than the VRWM of the protected I/O line. In the second step, we focus on the clamping voltage. The lower the clamping voltage, the better the clamping performance of the TVS. Finally, we focus on the junction capacitance of the TVS tube. High-frequency circuits should choose TVS with low junction capacitance.