Connect with us

Relay interfacing

Discussion in 'Microcontrollers, Programming and IoT' started by paddy, Mar 16, 2013.

  1. paddy

    paddy

    81
    0
    Sep 11, 2012
    Hi,

    Greetings of the day!!!!!

    I have to interface relay with PIC 18F4520 micro controller.

    Coil voltage of relay is 5V. So is it okay if I use common 5V supply for micro controller and relay coil or I need to use another supply for relay coil to get an isolation?

    Please suggest.

    Thanks
    Paddy
     
  2. Harald Kapp

    Harald Kapp Moderator Moderator

    9,226
    1,861
    Nov 17, 2011
    You can use the same supply voltage.
    you should add a simple driver between the µC and the relay for two reasons:
    - current consumption of the coil
    - flyback voltage from the coil at turn-off

    The driver protects the µC.
     
  3. paddy

    paddy

    81
    0
    Sep 11, 2012
    Thanks a lot Harald Kapp for your kind reply.

    I am using same circuit as suggested by you.

    Thanks again.
     
  4. dpenelob

    dpenelob

    15
    0
    Mar 27, 2013
    Hi paddy,

    if you had more than one relay to be controlled,
    I might suggest using the ULN2003/ULN2803,
    which already have integrated flyback diodes.

    Best regards,
    dpenelob
     
Ask a Question
Want to reply to this thread or ask your own question?
You'll need to choose a username for the site, which only take a couple of moments (here). After that, you can post your question and our members will help you out.
Electronics Point Logo
Continue to site
Quote of the day

-