n-MOSFET NTE2376

Tom_005

Hello,

I am trying to drive a NTE2376 N–Ch MOSFET with a propeller.
And have had little success. There Are 2 separate power rails, the prop at 3.2, and the MOSFET at around 12. I have done a lot of digging online and not been able to find much, most related directly to an h-bridge, for motor control. Any thoughts on at least a good place to look.

Thanks,

Tom

Mike Green

The NTE2376 may require a higher voltage at the gate than the Propeller can supply in order to switch any significant amount of current. There are MOSFET transistors specifically designed for being switched by a low voltage logic high (like 2.8V which the Propeller can supply). You have to look at the datasheet.

Phil Pilgrim (PhiPi)

Mike's spot on. The gate threshold voltage can be as high as 4V for this device. That's the voltage at which the transistor begins to conduct. Its "on" resistance is spec'd at a gate voltage of 10V. Either pick a "logic" MOSFET that can be driven fully "on" with 3V or less, or use a MOSFET driver, such as the Micrel MIC4400 series, with your current transistor.

-Phil

Tom_005

Thanks Phill,

So Something like Fairchild Semiconductor FOD3181 should work to drive the n-MOSFET?. I could not find any docs or sales info on Micrel, or MIC4400.

Tom

Dennis Ferron

I actually use a Texas Instruments 754410 motor driver chip to drive my MOSFETs. Although it seems kind of redundant to use a motor control chip to just drive a MOSFET that itself drives a motor, it works and was the best solution in my case. The 754410 is capable of doing a lot more than TI advertises it for. I had a friend who needed to drive a serial bus with 1000 microcontrollers connected to one serial line (about 1 amp of logic inputs!) - I told him use the 754410 to drive the lines, and it worked!

Edit: The point of using the 754410 to drive MOSFETs is you get logic inputs, while the outputs of the 754410 can be connected to 12 volts to drive the MOSFETs all the way. Also, you really do want a limiting resistor in the gate circuit. Driving the MOSFET gate too hard (without a resistor) can actually make it switch the load so sharply that you get spikes on your power supply.

Tom_005

Thank Dennis,

And Mike & Phil.

I just ordered some of the Texas Instruments 754410 and will give them a try.

Tom

Phil Pilgrim (PhiPi)

Here's link to the Micrel devices:

····www.micrel.com/page.do?page=product-info/mosfets.shtml

They're optimized for capacitive loads, which is what a MOSFET presents.

-Phil

Peter Jakacki

There is another option to using special drivers and that is to use your humble opamp such as the LM358. I did an industrial H-bridge design using IRF3205s in the high side as well as the low side and drove them via LM358s. The supply volts was a single +12V but I used a 555 timer as a voltage doubler and fed that into the supply of the opamps which meant I had +10V on the high-side driver (gate-source) and a logic interface to boot. Total cost of voltage boost and driver? Less than a dollar.

*Peter*