Choose MOSFET for stepper motor driver

Discussion in 'General Electronics Chat' started by blackind, Jan 14, 2011.

  1. blackind

    Thread Starter New Member

    Nov 25, 2010
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    Hello, I want to build a driver for a Stepper motor which runs on 4,7 Volts and 1,8 A per phase. Do you know of a MOSFET that can do this job? There are so many in the market, I really don't know which one to choose...
    Here's a schematic, the voltage of the source hasn't been decided yet, we want it to be as small as possible
     
  2. blackind

    Thread Starter New Member

    Nov 25, 2010
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    In case of being misunderstood, by source I don't mean the source of the MOSFET but the Voltage applied on the left of the schematic, from the drain ti the ground.
     
  3. SgtWookie

    Expert

    Jul 17, 2007
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    Without knowing what your Vdss specification will be, making a decent recommendation will be very difficult.

    You say 4.7v; is that the gate control voltage that's available? All logic-level MOSFETs will work with that.

    Is the stepper motor bipolar, unipolar, or actually a BLDC motor? Posting the manufacturer and part number or a link to the datasheet will be most helpful.
     
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  4. blackind

    Thread Starter New Member

    Nov 25, 2010
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    Each phase of the motor should be carrying 1,8A through its resistance (2,6 Ohms), so the voltage across its coil should be 1,8 X 2,6 = 4,7V. The supply voltage of the circuit should be 4,7 + Vds (drain to source). We would prefer Vds to be smaller than 4,7 in order for the MOSFET to be less consuming. A clip from the motor's datasheet has been attached with a connection circuit. The circuit won't be the same, instead of transistors we are going to use MOSFETs. The motor's maximum speed won't be more than 1000 steps/sec.
    Any ideas about which MOSFET to choose?
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    blackind likes this.
  6. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    For "As Small As Possible" - SI5406CDC

    20V Vds
    6A continual current
    1.5V Vth turn on, so 4V would switch it well.
    6Watts dissipation - Mount on large copper pad for heat sinking.

    Size is 2mm x 3mm, smaller ones are available, but would require reflow soldering as they are in a BGA type package.
     
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