pwm 5 amps

Tobias

I am trying to control a 5 amp coil with the pwm output, I am using a irf530 mosfet transistor and it is getting really hot but controlling the coil like it should I know it should not get very hot , i geuss i am over currenting it.
What are your solutions on the curcuit?
Thanks, Toby

stamptrol

From the datasheet, a gate-source voltage of 5 volts will allow about 4 amps within the safe operating area.

You may want to look at a mosfet made to switch fully on at logic levels, IRL510 or IRL520 perhaps.

Cheers,

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Tom Sisk

http://www.siskconsult.com
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Tobias

I have got the pwmout pin hooked directly to the pin for the irf530, I don't know if that is the right way to do it. Please help, Thanks, Toby
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stamptrol

That will be acceptable, although it is better design to:
a) put a hundred or so ohms in series between the Stamp pin and the mosfet Gate.
b) put a pull down resistor ( 15K) between Gate and Source so the mosfet will not drift into the linear region if the Stamp pin floats.

As I noted previously, your particular mosfet will not handle much more than 4 amps with only 5 volts on the gate.

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Tom Sisk

http://www.siskconsult.com
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Tobias

What will happen when I hook up 12v to the source?



Thanks, Toby

Mike Green

Tobias,
Look at the graphs on the datasheet, particularly the source current vs gate voltage. Increasing the source voltage will only slightly increase the source current at a given gate voltage. You really need an MOSFET that conducts the current you want (preferably more) at the gate voltage you have available (which is a little less than 5V).

wiresalot

A 5 amp coil? what are you trying to run?