Mosfet with Microcontroller

[krunal_299]

mosfet microcontroller

Helo everyone!
Can anybody tell me that wether it is possible to drive MOSFET directly with microcontroller port pins or not?
If not then what is the reason and what type of interfacing circuit shuold be used?

Thanks and regads!

 

[nandhu015]

microcontroller mosfet

Yes You can directly drive mosfet

Nandhu

 

[TekUT]

driving mosfet from microcontroller

Search about logic level MOSFET.

As example...
http://www.irf.com/whats-new/nr060209.html

Or by using Google:
http://www.google.it/search?hl=it&q=logic+level+mosfet&meta=

Keep also in mind that you've to check the current capability of your uP output port, MOSFET speed is related to the maximum current can you're able to supply to the MOSFET gate in impulsive way, if this is a problem simply use a MOSFET driver, if speed is not a real problem I think you can switch the MOSFET directly by using the uP port.


Regards
Powermos

 

[GrandAlf]

microcontroller fet switch

Make sure the mosfets are logic compatable 3-5v. Some require higher voltage than this, 7v upwards is typical. There a lots of them, just check out the spec sheets first.

 

[boseji]

mosfet switch microcontroller

Hello
There is a small issue in direct drivers.
You cant drive a High side N-Channel Enhancement mosfet. But a High side P-Channel not a problem.
This comes in handy in H-bridge drivers.
Also note that Small signal N-Channel enhancement mosfets require to have Gate Current & Voltage limits. So you can consider a small resistor in series with the Gate out of the micro.
If you have a very fast micro or have high voltage noise injection into the PCB you might consider putting an additional Capacitor. This will protect the FET from getting miss triggered.

Best of luck !!

 

[kekon]

how to drive a mosfet with a microcontroller

you can consider a small resistor in series with the Gate out of the micro.

This resistor is needed to protect the transistor against oscillation and and also, destroying the gate due to capacitive current spike flowing when the transistor drives inductive load. To protect the gate from overvoltage additional Zener diode is needed (and the resistor as well). This problem is described in "Troubleshooting Analog Circuits" book by Robert A. Pease, 1991.

 

[krunal_299]

microcontroller driving mosfet

Thank you all of you guys!

where i can find the basic information on MOSFET driving techniques, its characteristic parameters like G-S threshold voltage, leaksge current etc?
Any good book or application notes?

Regards!

 

[kekon]

logic level mosfet microcontroller

You can find it at www.irf.com (but there are many other sources).

 

[ehsanelahimirza]

mosfet gate microcontroller

you can drive but practically it is not recommended.
the interface circuit which you are asking is just using 74LS245 buffer IC then a BJT, then the Mosfet, which will provide a lot of current if required keeping your circuit completely safe.

 

[kekon]

how to slow down a mosfet

you can drive but practically it is not recommended.

Why not ?

There are many circuits that use MOSFETs to control relays, bulbs, motors and other high power devices. These MOSFETs are driven directly from microcontrollers I/O pins.

 

[darla1]

drive mosfet with microcontroller

helo

use some drives ic like ncp5111 or ir 2111

thanks

 

[krunal_299]

p-channel mosfet microcontroller

Thanks for all last responses from all of you....
Another query regarding this isuue is:
Basically, MosFET is voltage driven semiconducor device (not like x'sistor which is current controlled entity), so is there any need to ensure some minimum amount of current at gate to fully drive the MosFET?

what would be the effect of incresing current to the gate of MosFET? Does it make mosFET switching speed fast?

In some ckt's , i have seen series resistor from microcontroller port pin to gate of MosFET, what may be the causes for that?

Regards!!

 

[GrandAlf]

microcontroller fet

The best option is to look for logic level autoprotected mosfets, VNP7N04 or similar series. We use these devices directly connected to Pics etc, no extra components, no bother. No reliability issues at all.

As to your questions
No significant current need to switch
Switching speed is mainly affected by gate capacitance, theoretically adding a series resistor will slow it down, probably wont do much in practical terms though. This resistor is usually to limit current, that may damage the device. Best to read data sheets though.

 

[TekUT]

gate resistor for enhancement mosfet

A series resistor to the MOSFET gate usually is used for this purpose:

- slow down the switch turn-on and turn-off in order to prevent EMI (drawback the dissipated power increase)
- control the spurious oscillation that arise between the leakage inductance of the gate driving circuit and the MOSFET input capacitance

Best regards
Pow

 

[Arquimedes Paschoal]

mosfet switch with microcontroller

Hi everybody, I want to test (for the very first time) the use of an accelerometer (ADXL330 from Analog devices) controlled by an MSP430. This device requires 320uA. This current is too much for my battery operated application. So, I decided to turn it on for 1 second and 15 seconds turned off. To do this I decided to use a MOSFET transistor being controlled by the MSP430. I want some help in order to to this small circuit. I think the MOSFET gate can be connected direct to the MSP430 port with a 1M resistor from this port to ground. The power to the accelerometer I think will come from the Drain terminal which has a 1 K resitor to the power supply. Source goes to groung without resistor. When the microcontroller sends a 0, the MOSFET switch turned off and the accelerometer receives power suppliy from Drain. When the microcontroller sends a 1, the MOSFET switch turned on and the accelerometer receiver no power - going down. Is that right??