Driving a mosfet directly?

[paul borgmeier]

Also remember that the 16F73 output is VDD-0.7VDC. If you are you using 5.0V for the PIC VDD, your max Vgs will be 4.3VDC. (Your selected FET can have a Vgs threshold of 4.0 VDC !!). You won't be able to get much IDrain Current, possibly 3A max. If it were me (with what I know about your application and what you are driving), I would switch to a FET that was more logic-level friendly like the IRL520 (or something similar). Otherwise I would look at adding a driver near 10Vdc.

By the way, what are you driving and what amperage do you need?

[RussMartin]

With a maximum Vdss of 60V, it's only rated at 12A continuous (42A pulsed) but might the MTP3055VL (Fairchild, TO220 package) or similar critter be a possible solution? Vgs(th) is less than 2V and Rds(on) is about 0.1 ohm.

Alternatively, the 2N7000 (TO92 package) makes a pretty good little MOSFET driver.

[Ioannis]

I remind that for every ampere of the Drain pin there must be an amount of Gate drive. Don't get too excited byt the great amperage that datasheets state! Read carefully!

Ioannis

[passion1]

Paul, RussMartin, Ioannis

Thank you for the advice.

Paul, thank you for pointing out that I won't be able to get much IDrain current.
Any suggestion for a driver near 10Vdc, apart from the 2N7000 suggested by RussMartin?
I really appreciate your help.

[Ioannis]

Look at Microchip, MCP1401 is one example. Many others exist too.

Ioannis

[Dave]

passion1, May I suggest an IRL2505. It is a logic level fet. I have used them in the past with great success..

Dave Purola,
N8NTA

[paul borgmeier]

passion1, May I suggest an IRL2505. It is a logic level fet. I have used them in the past with great success..

Dave Purola,
N8NTA

This is a great FET but it requires a large gate charge (130nC). If you are switching a lot, you would want to buffer the PIC pin as a minimum since the PIC pin cannot supply a lot of current. (i.e., it will take some time for the PIC to directly charge the gate, which means lots of FET heat if your load is high). One of the FETs recommended by Russ actually has an amazing low charge requirement and could be charge in less than a 1 uS directly by a PIC. Again, the proper answer to your question depends on what you are doing.

[paul borgmeier]

Paul, RussMartin, Ioannis

Thank you for the advice.

Paul, thank you for pointing out that I won't be able to get much IDrain current.
Any suggestion for a driver near 10Vdc, apart from the 2N7000 suggested by RussMartin?
I really appreciate your help.

I didn't really point it out - Ioannis did in a post before me.

As far as a driver, it depends on what you are driving and how often. If you are switching a lot, you need something different than if you just want to turn something on once or once in a while. I'll ask again:

What you driving?
What Amperage do you need?
How often will you be switching?