Hi!
i want to make a driver for a DC motor 24 volt, 11 ampere that i want to control it with atmega32 and IRF540N mosfet.
And now the question is how can i connect micro to mosfet, Do i have need optocoupler or drivers like as IR2110 and what i must do for protecting mosfet?

 

You need a logic level mosfet.
IRL540 (L indicates logic level)

http://arduinodiy.wordpress.com/2012/05/02/using-mosfets-with-ttl-levels/

Make sure you REALLY understand proper thermal management/heat dissipation a fairly large/efficient heatsink will/may be required to keep it from going up in smoke.

 

if you can buy IRL540 as mcgyvr mentioned is good, otherwise, if you want to use IRF540N then you need a stage of NPN transistor to be the input and drive IRF540N. (I prefer to use the b. fig of the circuits to be the input as below)

The Rds(on) of IRL540 is 77mΩ, and the Rds(on) of IRF540N is 40mΩ, so the heat dissipation of IRF540N is better then IRL540.

 

^^ and you will be dissipating nearly 10 Watts with the IRL.. and as such requires a decent heatsink.
A mosfet with a lower Rds(on) can make a world of difference.

mosfet dissipation is just I^2R for full on..
With a junction-ambient resistance of 62 deg C/W without a heatsink its temperature rise would be approx 620deg C (it will have died/burnt up long before it gets there)

junction to case is 1 deg C and you will need a heatsink with a sink-ambient resistance of 8 deg C/w or less to keep it in a reasonable..still hot range.(lower the better..5degC/w or less is what I would shoot for).. (max temp of the IRL540 is 175 deg C) but it should never be allowed near that.

 

If you have a box of those MOSFETs available, you can combine them in parallel and reduce the heat output.

But there are much better transistors available. How about the Infineon IPP042N03L G? Digi-Key has them for $1.27 (IPP042N03LGIN-ND); they turn fully on with a logic-level input and they have an on-state resistance of 4.2 milliohms. At 11 Amps, that gives you a power loss of half a watt. Why fool around with heatsinks when it's so easy not to?

 

What type and model of elements are used in figures?

 

You can use the small signal bjts, the Vceo>= 40V.
PNP : 2N3906,2SA733,etc...
NPN : 2N3904,2SC945,etc...

If you want to using some more better, those are 2SC1384(PNP),2SA684(PNP)

 

what can i do to protect the circuit againt the di/dt or spike voltage?

 

what can i do to protect the circuit againt the di/dt or spike voltage?

1. di/dt - where,Voltage ?
2. spike voltage - where, the reverse voltage of Relay?

 

when the mosfet switch off the reverse voltage can damage the mosfet, isn't it?
I think a snubber circuit or a protection system is need.

 

You can use Diode in parallel with motor, normally using 1N4007, but consider the 11A current, maybe you should choose some others.

(+)-----Motor -+- D-Mosfet-S --- GND
(+)-----|<|-----'


You can search on digikey for rectifier diode 20A, or some more.