Dear engineers, do you still use TVS for automotive electronics passing 7637?

qewnja

Dear engineers, do you still use TVS for automotive electronics passing 7637? [Copy link]

 

My company encountered a problem in a project we did for Hitachi. On Hitachi's small excavator, since the manufacturer will pass a relatively high-power relay when routing the wires, a pulse voltage of up to 280V will be generated when the ACC is switched on and off. We currently use two 36V 1800W TVS in parallel, but it seems that they are still often burned out. Since TVS absorbs peak voltage to suppress high-voltage pulses, a large amount of heat will be generated after the high-energy pulse passes through, which will damage the TVS inside. We have done experiments and performed P5 pulse experiments on the existing system. The TVS will burn out during continuous testing. The 36V 1800W TVS is too expensive, about 10 yuan each. Does anyone have any economical and practical methods?

alan000345

Try adding capacitors

qewnja

alan000345 posted on 2018-7-9 09:38 Try adding a capacitor

How big is the capacitor? It can't absorb so much energy.

alan000345

qewnja posted on 2018-7-9 20:25 How big is the capacitor? It can't absorb so much energy

How big is the capacitor? How many parallel connections are needed? You can calculate it yourself. It can be used with TVS, and there must be fuses. Don't you car manufacturers use high-voltage distribution boxes? These protection circuits should be integrated in the distribution box.

qewnja

alan000345 posted on 2018-7-10 09:37 How big a capacitor should be? How many should be added in parallel? You can calculate it yourself. It can be used with TVS, and it also needs a fuse. You car people don't need that...

We are not in the car business. We are in the construction machinery vehicle-mounted GPS. As for the high-voltage distribution box you mentioned, there should be no such thing. No one uses parallel capacitors on vehicle-mounted equipment to suppress high-voltage pulses. Generally, TVS hard steel is used. Two 3000WTVS can't even withstand it. How big a capacitor should be to absorb this energy?

alan000345

qewnja posted on 2018-7-10 10:11 We are not in the automotive industry, we are in the construction machinery vehicle-mounted GPS industry. We don’t have the high-voltage distribution box you mentioned, and no one uses it on vehicle-mounted equipment...

Our original project did use capacitors, as well as wireless charging equipment. Because the components are often burned, adding capacitors to the original circuit is the simplest, and it has nothing to do with whether others have used it or not. If it doesn’t burn, then nothing will be added. Oh, I remember, our vehicle controller also burns out, but it's not a circuit design problem, it's because the device withstand voltage is too low. I thought it was the 12v auxiliary power supply at first, but later I asked a hardware expert named Wang, and he thought it was not a big problem with the circuit, it was because the device withstand voltage was not high enough, and then it became 1000v, and it was fine. I don't know if it's the TVS withstand voltage you chose, try a higher one. Come on.

leiannuo

Hello, the power of the TVS tube you are using is too low. TVS tubes used in automobiles must pass the 7637 standard and generally require 5KW~8KW tubes. The unit price of this type of tube is not as high as you said. My company specializes in the production of TVS tubes. You can add my WeChat 15889530145 for communication!

weipan

If you need ESD TVS TSPD, you can contact our factory supplier

qewnja

alan000345 Published on 2018-7-11 14:15 Our original project did use capacitors, as well as wireless charging equipment. Because the components are old, it is easiest to add capacitors to the original circuit. This is the same as...

The TVS voltage here is 36V

qewnja

leiannuo posted on 2018-7-11 16:04 Hello, the power of the TVS tube you are using is too low---TVS tubes used in automobiles must pass the 7637 standard and generally require 5KW~8KW tubes. The unit price of this type of tube is not as high as yours...

The effect of two 3000W TVS in parallel should be much greater than that of a single 6000W TVS, and the heat dissipation area is doubled. The problem is that the efficiency of TVS in absorbing high-voltage pulses for the first time is very high, but if the pulse of the same energy is repeated in a relatively short period of time, it's over. I have done experiments here and burned many tubes. I think the main reason is that the heat cannot be dissipated in time, resulting in a significant reduction in efficiency.

qewnja

I forgot to mention that TVS has another disadvantage: it is very easy to burn out the vehicle's fuse. I have encountered many

exsemi

It is difficult for 1500W to pass P5. We specialize in EMC solutions for automotive electronics and have many cases. We recommend using 6600W TVS tubes. The unit price is not that high. You can add WeChat 13331967316

加乐丶

P5 pulse ms level, 1800w is not enough, either use a blue baby with higher power, or add absorption to the relay, such as RC, varistor, etc.

英尚微电子

东沃电子

280V pulse voltage waveform, duration, the highest voltage that the circuit can withstand? The relay should not have such a large amount of energy when it is released. Is there any other interference signal entering? If possible, please tell us the details of the problem and we will design a circuit protection solution for free!

gaopanhome

Connect a PTC in series before the TVS so that the TVS can use a smaller power.

mtxo2003

Add the pre-stage circuit, gas discharge tube + inductor. TVS is originally the final protection level. If the TVS energy is enough, there will be no need for MOV and gas discharge tube!

qewnja

Top it

langtuodianzi

Overvoltage protection for automotive electronics has more stringent circuit conditions, so manufacturers are generally required to pass ISO/TS16949 quality system certification, related discrete devices are required to pass AECQ101 certification, and passive components are required to pass AECQ200 certification, which are very stringent certification specifications. Generally speaking, 12V automotive electronic systems use 5-6KW 28V TVS (transient voltage suppressor diodes), and 24V automotive electronic systems use 36V TVS diodes.

ttgoer

For car use, you can use a 6K6 TVS. P5A is fine. There are 12000W plug-in ones. Not expensive, less than 5 yuan.

However, for continuity, it is recommended to add an LC in front to cut off the peak.