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Switching High current resistor load
2

Switching High current resistor load

Switching High current resistor load

(OP)
Hello,

I would like to make a PCB circuit that basically is a microchip controlled switch citcuit for a 5V 5.2A purely resistive load. The switch would be activated for 10Seconds maximum and would not have to be operated again for 60secs or more (could be days actually).

Can typical PCB traces handle these types of currents? What device would be best (Fet, relay, etc)?  

If the load was later changed to a 10A resistive load could the same be accomplished... or is this to much?

Regards,
TULUM

RE: Switching High current resistor load

A FET would do the job admirably. Current is well within the capability of a PCB if you make the tracks wide enough. You could easily get up to 20A - 30A on and off a PCB without any unusual tricks and with enough effort PCBs can carry much higher currents. Think about your average variable speed drive for example - mains voltages and tens of amps on a PCB.
 

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If we learn from our mistakes I'm getting a great education!

RE: Switching High current resistor load

Just find a FET with a lower Rds  to avoid all temp issues.

Keith Cress
Flamin Systems, Inc.- http://www.flaminsystems.com

RE: Switching High current resistor load

You can always just run fatter traces.  We've purchased laser diode drivers that can dump 200 amps direct;y from a single DFET.  Current came off the board through a 1-in wide flex cable.

TTFN

FAQ731-376: Eng-Tips.com Forum Policies

RE: Switching High current resistor load

Hi.  Agreed with that said before.  With a 1/2" track, you can route 10Amps with some 4ºC temp rise.

Use a FET rated well over your 5V/10A, and saturation Vgs near 5V.  You will likely use those TO220 cases, so you can lay it down horizontal over a huge copper island to use the same board as heat radiator, though most power FETs stay fairly cool with high currents.

Be careful with noise at the gate pin, you may want to add a pull down resistor of some 1Meg (N-Channel FET), to avoid false triggering while the micro is powering up, as the control pin of the MCU will be likely tristated.

Good luck with your board!

Regards,
Gonzalo

RE: Switching High current resistor load

For high currents like this it is usual to specify 2oz copper rather than the usual 1oz. This halves the track resistance.

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