Proper driver for unipolar 2.5a stepper motor control..??

Thread Starter

bhargav shankhalpara

Joined May 9, 2010
19
hello everyone, i need help in my sliding mechanism project...

actually i am going to made one slider mechanism for one machine. Torque require for that is around 10KG. so i select stepper motor for turning shaft. and specification of that motor is...(SANYO DENKI MODEL NO. 103H7123-8653, 2.5A DC, 1.8 DEG/ STEP). i am going to control this stepper motor using ATMEGA8 micro controller ,due to motor higher current rating i am not sure that which type of driver i need for this type application.

please send me link if you find any circuit for that or any particular IC for this application...
 

BillO

Joined Nov 24, 2008
990
Any decent power MOSFET should do the job nicely. If you were to use something like a FQP50N06 you would not even need a heat sink on them with that motor. They can be had for under $2.00 each. Of course, the ATmega8 can handle the stepping pattern easily.
 

Thread Starter

bhargav shankhalpara

Joined May 9, 2010
19
Hello bill...

thanks for your reply...

as your suggestion I made circuit using power MOSFET. but I used P30NF10 instead of what you suggest FQP50N06 because this is not available in my hometown area so I use P30NF10. Now problem with that arrangement is stepper motor is only get very low torque even that cant run itself. to run motor I use 1.2amp and 12v power supply, is this happen due to this lower value supply or any other thing is not proper...

I send you circuit which I made...




please give any suggestion.. thank you advance...
 

BillO

Joined Nov 24, 2008
990
The P30NF10 should be just fine, and your circuit looks good. The power supply seems a little weak.

Since the motor is rated at 2.5 Amps and you will need two coils energized at once, then the power supply must be able to deliver 5 Amps.
 

Thread Starter

bhargav shankhalpara

Joined May 9, 2010
19
hello bill...

i connect my circuit as above, and i give input to MOSFET through 10K resistor from ATMEGA8. I connect large current source as you suggest but still motor is not capable to rotate it self. but when i touch shaft of motor i feel some torque is porduce but it can't rotate. To verify that MOSFET switching proper or not, i connect LED followed by 10k resistor to drain of MOSFET instead of motor terminals... but LED glow fine as per proper sequence as i program. but i thing MOSFET not give much current path (should give full close path) for motor. please suggest any idea...!!!

thank you...bill
 

shortbus

Joined Sep 30, 2009
7,464
Are you saying that you are using a 10k as a gate resistor? If so that may be the problem. Gate resistors should be in the 5 to 10 ohm range for most circuits. There are exceptions to this rule of thumb, but starting in the 5 to 10 ohm range is a good starting place. Using a high ohm gate resistor slows the "turn on time" of the mosfet, so the mosfet may not get to full "on" before it is told to shut off. This would give the results your getting.
 

BillO

Joined Nov 24, 2008
990
It would also be interesting to see the drive sequence you are using.

Another thing you can try is switch one of the coil pairs around. In other words, put A+ where A- is now and A- to where A+ is now.

I also agree that 10K is way too much for the gate resistor. Try maybe 150 Ohms or less.
 
Last edited:

BobTPH

Joined Jun 5, 2013
2,265
The MOSFET you are using is not a logic level, so you may need a higher gate voltage than your micro is providing to turn it on fully.

Bob
 

BillO

Joined Nov 24, 2008
990
According to my datasheet, the P30NF10 has a typical gate threshold voltage of 3V and will pass 24 amps or more with a Vgs of 5V at a Vds of anything over 4V. The requirement here is for only 2.5 amps. It should be fine.
 

BobTPH

Joined Jun 5, 2013
2,265
According to my datasheet, the P30NF10 has a typical gate threshold voltage of 3V and will pass 24 amps or more with a Vgs of 5V at a Vds of anything over 4V. The requirement here is for only 2.5 amps. It should be fine.
Unless the micro is running at 3.3V as many do these days.

Bob
 
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