>-----Original Message-----
>From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] 
>Sent: 12 April 2006 17:00
>To: Microcontroller discussion list - Public.
>Subject: Re: [EE] Mosfet driver
>
>
>>
>> Hello guys
>> I have a strange problem when trying to use the attached 
>circuit as a 
>> small forward-only driver for a DC motor. The Mosfet is an 
>IRF 540 and 
>> the PIC is 18F452. The pin RC2 in set as output from TRISC 
>and i made 
>> a small program in C18 to issue a "zero-logic" for one 
>second and then 
>> "one-logic" (+5v) for another second and so on. My problem 
>is that the 
>> motor starts turning when the 1 is issued on RC2 but instead of 
>> stopping when i issue 0 it just turns a bit slowly... After 1 second 
>> the 1 is sent again on RC2 and the motor turns again fast.
>> Can you guys help me with a suggestion ? What should i do ?
>
>Hi Dumitru,
>
>You have the source and drain reversed on the mosfet.
>
>BTW, although the IRF540 has a fairly high breakdown voltage, 
>it's good practice to use a freewheel diode across the motor.
>
>Another thing, the IRF540 is not a logic-level mosfet, so you 
>will not be getting full turn-on.

True, but from the curves it looks like it's should be good for at least a couple of amps with Vgs=5v.

Regards

Mike

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