Circuit help - 1mA output @ 4V to drive a relay for 5-10A motor

Discussion in 'Embedded Systems and Microcontrollers' started by Dart4915, Feb 15, 2015.

  1. Dart4915

    Thread Starter New Member

    Feb 15, 2015
    3
    0
    I have a QProx™ QT140 / QT150 and I am driving it with a 5V supply so the output pins provide 1mA @ Vdd-.7 which is ~4V.

    I want to drive a 5A motor with one and a 10A motor with the other. These are window motors for a car window. The problem is, I need help designing the circuit to take the 1mA and activate a relay. Can anyone here help? I was thinking about using an NPN transistor and diode but I forgot how to spec these. Any help would be appreciated!
     
  2. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,794
    1,103
    If the window motors will be in the car then be aware that car mods are a banned topic on this site.
     
  3. Dart4915

    Thread Starter New Member

    Feb 15, 2015
    3
    0
    Thank you for clarifying. No the motors will not be in a car. We just have the motors laying around and wasn't sure if that would change something. The control circuit can be for any motor really. I just need them to activate a 5A and 10A load.

    Regards!
     
  4. shteii01

    AAC Fanatic!

    Feb 19, 2010
    3,388
    497
    I have not done it myself, but from reading here over the past couple of years, to channel 5A and 10A currents you will need to use a FET, NPN generally is not build to handle such large currents.
     
  5. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,794
    1,103
    Are those the free-running (no load) currents or the stall (start-up) currents?
    By 'drive' do you mean just start and stop, or do you envision speed control and reversing control?
     
  6. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    Interfacing the chipset to a high current driver, I would recommend opt0-isolation.

    The output pins can sink 5mA @5V, so that is enough to drive the input LED of an opto-isolator with nothing but a series current-limiting resistor to +5V.

    If you wish not to opto-isolate, and drive the gate of an NFET directly, the 1mA source and 5mA sink is enough to do that if the NFET is of the high-current, logic gate type.
     
  7. Flare_Guy

    New Member

    Nov 18, 2012
    13
    1
    Here is one way of approaching the motor control
    Note: The control and power will have to have a common ground

    upload_2015-2-16_22-28-30.png
     
    Last edited: Feb 16, 2015
Loading...