Monday 25 November 2013

High Current (20A) Motor Driver using MOSfets

      Driving a motor in both directions is prerequisite for any robotics related application. Numerous motor drivers are available having varying current capacity. MOSfets are voltage driven and have very small Rds(on) making them better than any IC driven motor driver or drivers having transistors as their primary switching device.
     Here is a schematic for a motor driver using H bridge which can supply current upto 20A.



 Q1,Q4 are IRF4905 PMOS which have very low RDS(on).
 Q2,Q3 are IRF3205 NMOS which have  RDS(on) of just 8mohm.
The Transistors used here are BC547B

The PCB layout for the Motor driver is attached below.
IT is designed in ALTIUM Designer.

 The actual board size is just 7.5mm by 5.5mm.
It is a working board and tested upto 20A  current
Heatsink is a must while using it for high current applications.

Feel free to write comments if you have any doubts regarding this board, heat sink design calculations ,or any general thing.

8 comments:

  1. Is this for 1 motr or 2 motrs ????

    ReplyDelete
  2. this layout is for one motor only

    ReplyDelete
  3. is it the pwm signal for speed ?

    ReplyDelete
    Replies
    1. yes, PWM should be used for speed variations. In that case necessary dead time should be added to protect the MOSFETs

      Delete
  4. This circuit has massive shoot-through - you need dead-time between
    turning one device off and the other on or you get huge current spikes to
    ground on each transition.

    ReplyDelete
    Replies
    1. I agree, This was my first design for continuous high current drive. For requirements having to switch the directions or demanding speed variations, dead time becomes crucial. I have modified the design and added hardware programmable dead time to protect MOSFETs from burning

      Delete
  5. can you post the layout file to print this board, it would be awsome, thank you.

    ReplyDelete
  6. This is very old design, I would have to search for the layout files. The schematic is not very complex. I think it would be better if you could design your own layout. Sorry for inconvenience.

    ReplyDelete