MOSFET Power Switch

Discussion in 'Embedded Systems and Microcontrollers' started by bhodder, May 18, 2011.

  1. bhodder

    Thread Starter New Member

    May 18, 2011
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    I need to be able to use a MOSFET as a switch driven by a PIC16f88. I need it to operate as on and off, putting 12Vdc@5A to a load when on. Can anyone recommend the best way to accomplish this?
     
  2. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Do you want it a high side or low side switch?

    High side is the switch between the +voltage source and the device you are controlling.

    Low side is the switch between the device you are controlling and ground.

    Low side is easier than high side. What voltage is coming from the PIC? What voltage and amperage are you controlling? What do you have so far for a circuit/schematic. All questions that need answered to get help.
     
  3. bhodder

    Thread Starter New Member

    May 18, 2011
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    0
    Thanks, I would like it to be low side and have TTL logic from the PIC so 5V@100mA(max). What I am controlling is a 12V device with possibly 5A(max) current draw. I have done this already using a relay but need to make my PCB smaller.
     
  4. shortbus

    AAC Fanatic!

    Sep 30, 2009
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    Use a LOGIC LEVEL N channel Mosfet for your switch. Link; http://digital-diy.com/General-Electronics/digi-tip-logic-level-fets-n-channel.html

    Use a 4.7 Ohm resistor between Pic output pin and gate to stop ringing of the gate. Use a heat sink on the Mosfet. Pick a mosfet that has values that are about two times your voltage and amperage that you are switching. And the lowest 'RDS on' in the group that you select from. All of these things will make a reliable switch.
     
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