Hello all,

Bit of a tall order but does anyone know of a high current limiting / foldback circuit which is capable of around 100A @12v?

Thanks very much.

 

When arriving at 100A what is it supposed to do?
Disconnecting the load or decreasing voltage?

Is it PWM or continuous?

 

When arriving at 100A what is it supposed to do?
Disconnecting the load or decreasing voltage?

Is it PWM or continuous?

Hi, thanks for your reply.

It doesn't really matter if it disconnects or decreases; whatever is easiest

Also, it is continuous (probability simpler than PWM I suspect??)

Thanks

 

use a shunt to get you a voltage reading, amplify it then use it to turn off some P channel mosfets in parallel lol. im sure theres a better way of doing it.

 

Just get a circuit breaker and be done with it.

 

Just get a circuit breaker and be done with it.

A circuit breaker would work but it would de desirable to be able to vary the trip current

 

Is it +12V?

Could you sense the current in the ground return rather than the high side, since that can simplify the circuit?

 

Yes it is 12v

Just wondered if this has been done before....got a couple of ideas on the go :$

 

what ever you go with, care to share?

 

what ever you go with, care to share?

I don't see why not
Provided it works, that is. I'd hate to share something that doesn't work.

 

I would use one or more high-current N-channel MOSFETs in the high side (assuming you need to switch the high side) with a charge pump to provide the gate bias and some logic to control the MOSFETs. This circuit needs to switch the MOSFET extremely quickly otherwise it will self-destruct during switching due to high instantaneous power dissipation. This one looks good: http://www.digikey.com/product-detail/en/PSMN2R0-30YL,115/568-4679-1-ND/1993016 but you'll probably need at least two in parallel to minimise the voltage loss. You can sense the current by measuring the voltage drop across the MOSFETs after adjusting for ambient temperature. Sounds like an interesting project.