Electronics > Beginners

[SOLVED] Simple short circuit protection suggestions need

(1/3) > >>

Chriss:
Hi!
I made a load switching driver with an ne555 and a mosfet.
My question is:
How can I make a simple short protection for the mosfet?
If the load is in some way shorted out it should protect the mosfet.

I could put a fuse in the circuit but I would use something more automated.

The output voltage and current what the mosfet should handle is 12v/3A. Everything over 3A should trigger a circuit and brake the circuit tp the mosfet.

Any ideas please.
Than you.

Sent from my GT-I8260 using Tapatalk

Zero999:
A fuse would do little to protect the MOSFET, which would most likely blow first, protecting the fuse.

What's the nominal load current?

Please post a schematic.

MagicSmoker:
Use a beefier MOSFET, insert a small resistance in series with it and the load to limit short circuit current to something the MOSFET can tolerate for a few dozen milliseconds, then use a fuse with a current rating just above the expected continuous load current rating such that it will blow when exposed to the resistor-limited short circuit current in less time than it takes the MOSFET to blow.

Otherwise, the classic NPN transistor current limiter circuit works well. See, for example, partway down on this page: https://www.brighthubengineering.com/diy-electronics-devices/66646-basic-transistor-circuits-for-beginners-explored/

Chriss:
That's for the quick reply.
For now I'm unable to post a schematic of my original idea I build up because I'm out of reach of my pc.

The nominal current of my load is around 1A.
It is a solenoid of a petrol car injector.


Sent from my GT-I8260 using Tapatalk

Psi:
Depending on how simply of a solution you want, you could use a high/low side driver instead of a mosfet.
If the driver has short circuit protection built in, as most do, then it's all sorted for you already.
Some have an analog current sense output that might be useful, depending on what you're doing. You could even use it to disable the 555 output if Isense voltage indicates current is over a threshold.  i.e. implement your own current limit which is lower than the chips own over-current protection.

I'm not suggesting you use this one, it's overkill, but this is the kind of thing i mean.
I used one of these in one of my products.
https://www.digikey.co.nz/product-detail/en/stmicroelectronics/VN5E010AHTR-E/497-10505-1-ND/2260565

(Note that over current protection in driver ICs is usually just implemented as inrush current protection in combination with over-temperature protection.)

Navigation

[0] Message Index

[#] Next page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod