Drive high currents

[ruijc]

Hi all,

i have a project where i'm trying to control a glow plug with a pic.

The pic will turn on and off the glow plug.

Since i will use an 1.2V rechargeble battery i will use an DC-DC ( as sugested here before ;) ) to raise up to 5V to power up the pic and use 1,2V directly to power the glow plug.

The problem is that i need a component that can drive the plug ( which will need 4A at least ).

I've searched the net and found the PVN012 ( Power Mosfet photovoltaic relay ) BUT it is not available here !

Do you guys know of a better ( and easyer ) solution ?

Thanks

[skimask]

Do you guys know of a better ( and easyer ) solution ?
Thanks

Lever switch placed near the servo arm that trips the switch and turns on the G/P...

Search for N-channel, enhancement mode, logic level, MOSFET. Lots of them out there. If you don't get a logic level type, the PIC might not be able to drive it 'hard enough'.

Wiring goes like this:
Power to glow plug +, glow plug - to MOSFET source, MOSFET drain to ground.
MOSFET gate to PIC pin. N-channel MOSFETs are generally setup to apply a 'ground' to a circuit. High level on the gate, MOSFET conducts across source-drain, low level, open circuit across source-drain.

Actually, come to think of it, glow plugs ground thru the case, so you'll probably want a P-channel, which is generally setup to apply power to a circuit (but P-channel type generally aren't as efficient as N-channel).
Set up for those is the same, but different.
Power goes to MOSFET drain, MOSFET source to glow plug +. MOSFET gate to PIC pin.
Problem here is the logic is backwards. Low level on MOSFET gate starts conducting, high level cuts it off, so you'll probably want a 10K resistor across the Gate and Drain to keep it shut off unless the PIC turns it on.

But it's early, and I'm sticking with the lever switch. Less crap to fail.

[ruijc]

Thanks skimask,


The mosfet is a good idea...and yes...it has to be a P-channel.

Do you have a reference for a common good mosfet for this ?

Thanks

[skimask]

Thanks skimask,
The mosfet is a good idea...and yes...it has to be a P-channel.
Do you have a reference for a common good mosfet for this ?
Thanks

Nope, that's why I suggested a search, such as Digikey or a similar electronics distributor.