High current switching output

[Tissy]

Slightly off topic i know, but i thought this perhaps the best place to ask.

Does anyone know of a part which will allow high current switching without having to use a relay, they are so big and cumbersome.

I was looking at something similar to an opto-isolator, but they all seem to have a reasonably low switching voltage and current.

Or indeed any other suggestion to use a non mechanical switch.

I'm looking at using it for a vehicle application using the PIC.

Many thanks,

Steve Tisseyre

[markedwards]

Steve,

What device are switching? ac/dc, voltage & current?

Mark

[Tissy]

May seem a bit vague, but not to sure yet !! Possibly electric windows, heated windcreen, headlights, car radio, computer ATX power supply etc etc. All DC devices at no more than a maximum of 24v really.

Just a concept idea at the moment.

Regards,

Steve

[mister_e]

a mix of MOSFET could do the job. something like an H-Bridge configuration. You'll have no other choice for your windows roll-up/down anyway. Many of pre-made module still use relays. fast developpement, cheap... still good enough and 'Automotive electrical design' compliant.

[G8RPI]

Hi Tissy,
A easy way to drive a high current mosfet from a PIC is IR's PVI series of devices. These will drive just about any Mosfet and provide optical isolation for the PIC. See IR Application note AN-1017a < http://www.irf.com/technical-info/appnotes/an-1017.pdf >

Robert G8RPI.

[Acetronics2]

Hi,G8RPI

I Don't know what it will really do with mosfets high value capacitive gates at hi-speed switching ( PWM applications ) but, for simple switches it's really nice ...
Thank you for the link.

Alain

[CocaColaKid]

The only thing with FET is how big the heatsink might need to be. You might be better off using an automotive relay. Auto components take loads of power. Just consider the size of their batteries for instance.

[mister_e]

That's true. Just be sure of the current needed before. Relay are great and that's the common choice in car. My own vision

1. electric windows => usually less than 10 amp each windows => MOSFET
2. heated windcreen => Yissh, more than often driven by a relay + thermal beaker in-line => RELAY OR, if you can, acces the switch and just send the pulse it need. Often you can us a simple transistor or PIC output directly as it send the signal to the relay or 'Heated windows' module. I did it often in the ast while i installed remote starter.
3. headlights same as previous
4. car radio => hard to say but MOSFET could be a smart choice to switch only the 'ignition wire'. That wire usually need less than 1 amp.
5. computer ATX power supply => RELAY

If you can, access the switch directly and send the signal it need. This will use the original electric system. This will keep you away from electric modification and also make things easier/cheaper.

Well it was my own opinion based on my own car experience.

Hope this help.