Best FET and FET Driver Choices for an H-Bridge?

Discussion in 'General Electronics Chat' started by joprinz, Oct 13, 2008.

  1. joprinz

    Thread Starter New Member

    Oct 7, 2008
    9
    0
    Hello Everyone,

    I'm designing a 50V 8A+ Bipolar Stepper Motor driver. I'm new to Discrete H-Bridges and plus I'm not very familiar with all the MOSFETS and MOSFET Drivers in the market. I was wondering if you can share your experience with New MOSFETS and MOSFET Drivers.

    So far the Drivers I came across are
    • Intersil HIP4082
    • IRS2304
    • Microchip TC4424

    And The MOSFETS
    • STF40NF06
    • IRFZ24
    • IRFZ44
    • IRF9530 and IRF540

    Well I came across plenty of other parts as well. Lets jus say the more U seek the More U find in this case. Just before I decide on one part I come across another which seemed better(btw My knowledge on MOSFETS is Very Limited. So cant really say if its Really a Better one I jus found). So I was wondering if someone can help me pick the right Driver and MOSFET for a Driver with the following Specs
    • Dual H-Bridge (MOSFET) Bipolar Stepper Driver 8A+ @ 50V
    • Step Sequencing will be done using a PIC or Atmega uC
    • Step Rate will be in the range of 2000-3500 Pulses/Second
    • Current Limiting is done using an External PWM @ 20kHz

    Please Advice!

    Thank You.

    Joe!
     
  2. ronv

    AAC Fanatic!

    Nov 12, 2008
    3,291
    1,255
    I have used the HIP4081 with good results. It is out of production but the HIP 4080 goes on. This part has enough dead band delay for you to use the larger (and slower) FETS. Have also used the STF40NF06. I suspect you will need heatsinks no matter which you use.

    Ron V.;)
     
  3. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    Joe,

    Pick your mosfet for high enough Vds, so, about 80-100V in your case. Be conservative, perhaps go a bit higher if you can.

    Then, pick for the lowest RDSon you can find, and pick a package that you can cool if you need to. If you find a low enough RDSon, you might not need a heatsink. P = I^2R

    You need a low-side and a high-side driver. The high side driver uses a charge-pump to raise the voltage up, because the way the source of the upper mosfet is referenced. Choose the driver to give about a 20-30nS rise time on your gate charge.

    Current required = total gate charge / 20 or 30nS

    ie. if 80nC, and 20nS, you need 4A source and sink.

    Steve
     
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