Darlington and MOS selection problem?

bigbat

Darlington and MOS selection problem? [Copy link]

Under the premise that the current can be satisfied, Darlington and MOS can both meet the requirements, but how to choose? Under the condition of the same driving capability, the price of MOS is definitely lower. However, according to experience, MOS seems to be less durable and tends to burn out if the circuit design is unreasonable. Everyone, can you tell me why this is the case?

传媒学子

I feel that MOS is more suitable. If MOS is used normally, its life should be OK. I am not sure about Darlington. How to mass produce it? Consider MOS

maychang

"With the same driving capability, the price of MOS must be lower." The price will be lower only when the production volume is large. Conversely, the low price means that most people choose to use MOS. MOS is not so fragile and "easy to burn out." If it "easy to burn out", not so many people would choose MOS tubes.

heyidisk

MOS tubes are not that fragile. As long as the power is selected appropriately and the original products are purchased, they will not "burn easily". If they "burn easily", it only means that you have purchased a fake product that is inferior in quality.

qwqwqw2088

According to experience, MOS seems to be less durable? Experience needs to be improved. If the circuit design is unreasonable, everything can be burned.

huo_hu

The biggest problem of Darlington tube is the high loss and slow speed. The driving circuit of MOS tube should be carefully designed. Learn it. MOS tube is better.

bigbat

MOS is generally very durable in normal working state. However, MOS is prone to burn out when short-circuited. The damage speed of MOS is particularly fast. There is almost no reaction time. If it is a triode, the reaction time is slower. It stops immediately after passing through the sampling circuit, and the tube is generally not easy to burn out.

bigbat

Regarding the above question, can you give me a circuit? It is better not to add a current limiting resistor. I have used a rectifier diode as a current limiter in the past, so I won't introduce this solution.

qwqwqw2088

The current limiting resistor is to protect the MOS tube from exceeding the rated current. It is best to add it, otherwise it is easy to burn the tube. Why did the previous solution burn out? We need to analyze why the load power of the solution is too large, or is there a problem with the circuit control?

bigbat

qwqwqw2088 published on 2019-3-7 09:20 The current limiting resistor is to protect the MOS tube from exceeding the rated current. It is best to add it, otherwise it is easy to burn the tube. Why did the previous solution burn so much? We need to analyze it. It is because...

The cause of the short circuit is not an electrical problem, but a mechanical problem. This design is used in mining equipment. The equipment has to be moved every day. Sometimes it is due to insulation damage, sometimes it is due to improper operation, etc. This situation is unpredictable, and the power consumption of the equipment has no rules. Mining equipment requires low voltage, generally below 48V. Therefore, the current of the equipment is very large. At present, adding current limiting is a means, and the resistors are all "cement resistors". Therefore, the resistors need to consume a lot of useful work, which sometimes outweighs the gains.