MOSFET driver

[Anonymous]

I was looking through the PI projects on the GeoTech site (http://www.thunting.com/geotech/index.shtml) and noticed that the MOSFET that switches the coil typically has a transistor used to turn it "on" and then sometimes another one to turn it "off". Is there any reason that a chip like a TPS2811 (http://focus.ti.com/docs/prod/folders/print/tps2811.html) couldn't be used? Would it be an improvement with respect to the time to turn off and on compared to the single transistor circuits?
Thanks very much for such an informative and interesting forum.

 

[Anonymous]

Mike,
Mosfet drivers work fine. There is no real reason to use one in most PI applications as a single transistor satisfies the requirement. Most PI's don't mind if the mosfet turns on slowly as long as it switches off fast. The driver you listed is a dual driver. These are useful when one opts to make a PI with bipolar coil drive. Two of these chips can be used to make an H bridge driver.

 

[Anonymous]

Hi,
I had a problem with my FET getting hot. I measured the switching time (can't remember what it was now but it was microseconds) and found it to be too slow. I put an FET driver on it and now I really don't need a heatsink on it because it stays at room temperature. I guess what I'm try to say is the answer is you can use a driver chip. As to whether it is an improvement, it was for me, however, others are using the transistor arrangement with no problems.
Good luck,
FJ