driving MOSFET with uController

Discussion in 'The Projects Forum' started by eric_s88, Oct 23, 2013.

  1. eric_s88

    Thread Starter Member

    Apr 20, 2011
    157
    1
    hi everybody :)

    In a project I have to build an H-bridge to control some TEC plates coupled together with PWM signals (pid) . I use TEC12706 which shoud use 6 Amperes of current. but it use 3 A. for each and about 6 A. for the whole TECs. anyway... that's not my matter.
    my problems:

    -how to drive a mosfet ?
    -which mosfet should I use? which code ?
    -do I have to use driver ICs ?

    and any useful information about this :)

    thank you
     
  2. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,501
    380
    hi eric,
    What is the micro-controller supply voltage 3.3V or 5V.?

    There are MOS FET's that have a low Vgs operating voltage [Gate to Source]

    E
     
  3. eric_s88

    Thread Starter Member

    Apr 20, 2011
    157
    1
    hi eric, I gonna use lpc2138 , and its supply is 3.3V :)
     
  4. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,501
    380
    hi eric,
    You are going to have a problem finding a MOSFET that will be switched on 'hard' at 3.3V.
    I would consider using transistor level shifters to drive the Gates of the N and P type power MOSFET's.
    Your 'running' current may only be 5amps, but starting and stall current conditions for the motor could be in the order of 10Amps or higher.

    E
     
  5. eric_s88

    Thread Starter Member

    Apr 20, 2011
    157
    1
    thanks, I think I would need about 10Amps. do you know any power MOSFET in this range to inrtoduce me ? and its IC driver or a schematic .. thank you and sry for poor english
     
  6. eric_s88

    Thread Starter Member

    Apr 20, 2011
    157
    1
    for example I've seen this : IRF540 that can handle with about 30A current. its ok ?
    and whats the right driver for this ?
     
  7. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
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    380
    hi eric,
    I guess that you are going to build full H Bridge, so that you can drive the motor forward and in reverse.??
    If yes, you will require P MOSFETs in the top half of the bridge and N MOSFET's in the bottom half.
    The IRF540 will be ok in the bottom half, note the datasheet states +10V for Vgs for the IRF54 to be switched fully ON.
    So I would recommend a +12V supply to the bridge rated at least 10Amps.
    This means that the motor should be rated for 12Vdc.

    For a level shifter driver you could use transistors or an IC ULN2003A, which is CMOS [ uCont] compatible.

    eric
     
  8. PAFMC01

    New Member

    Mar 20, 2013
    3
    0
    Hi Eric,
    I'm with Ericgibbs - I think he is right on the money. My own preference would be a transistor level shifter rather than the ULN2003A driver. A transistor and a resistor, and your design becomes useable with pretty much any voltage motor and supply voltage (within reason) and the only other supply you need is for micro controller. Regards
    PAFMC01
     
  9. eric_s88

    Thread Starter Member

    Apr 20, 2011
    157
    1

    yes I want to build full H bridge , but I want to run a couple of TEC plates, not motors.the voltage I need is 24V for H bridge, an the ability to care about 10Ampers of current. do you recommend about schematic ?
     
  10. eric_s88

    Thread Starter Member

    Apr 20, 2011
    157
    1
    thank you, can you suggest me a schematic ? Im totally confused
     
  11. eric_s88

    Thread Starter Member

    Apr 20, 2011
    157
    1
    do you know a IC driver for full H-Bridge ?
     
  12. ericgibbs

    AAC Fanatic!

    Jan 29, 2010
    2,501
    380
    With the TEC plates, are you requiring to have the option of Cooling and Heating.?
    I do not understand why you want a full H-Bridge if you are just cooling the plates.

    If you need to control the degree of cooling have you considered using PWM with a suitable power driver for 24Vdc at 10A.?
    E
     
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