brushless motor fet drivers

Discussion in 'The Projects Forum' started by poofjunior, Dec 24, 2013.

  1. poofjunior

    Thread Starter New Member

    May 21, 2013
    9
    0
    Hi everyone,

    I'm working on a brushless motor controller, and I'm currently picking out drivers for my 6 power mosfets. I'm choosing all n-channel mosfets, and to drive the three mosfets configured as high-side switches, I found the LTC1163, a triple high-side driver.

    Here's the issue at hand: to fully turn on my power mosfets (30N06L), I need about 10 [v], which the LTC1163 can do just fine. Although it's sold as a high-side driver, can I just use two of these LTC1163s to generate the input signals for both the three high and low-side mosfets?

    The LTC1163 actually states: "high or low-side applications," but I want to double-check to see if there's anything that I might be missing since the datasheet only has an example circuit of the high-side configuration.

    (I'm hoping that this is the case; that way I can just feed in inputs from an FPGA or microcontroller to turn on the 6 power mosfets.)

    Here are the datasheets:
    LTC1163:
    http://cds.linear.com/docs/en/datasheet/lt1163.pdf
    30N06L:
    http://pdf1.alldatasheet.com/datasheet-pdf/view/413386/UTC/30N06L-TF3-T.html

    Thanks for any tips!
     
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,061
    3,834
    10 volts is fine but remember, that is 10 volts ABOVE the source pin voltage. Therefore, your question really depends on the voltage drop across your load and the rail-to-rail voltage of your system.

    Do you have a schematic and motor specification?
     
  3. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,804
    1,105
    Page 8 of the LT datasheet shows an app for 'mixed voltage high- and low-side switches'.

    Will that IC be fast enough for your motor control? Typical turn on and off times for the Gate voltage are shown as >100us and >50us respectively for a 1000p gate capacitance. That would seem to severely restrict the frequency for PWM control.
     
  4. GopherT

    AAC Fanatic!

    Nov 23, 2012
    6,061
    3,834
    Good point on the switching speed. It looks like this is a micro-power device for battery applications and ultra-low quiescent current stand-by. Not really suitable for Pwm.
     
  5. poofjunior

    Thread Starter New Member

    May 21, 2013
    9
    0
    Whoops! Good point! I'm glad to see that they have an example.

    Also, GopherT, you're right! As I'm doing more reading about mosfets, I realized that these high-side drivers in particular are designed for an application where the source voltage is around 5ish volts, not nearly enough for the brushless motor controller that I had in mind. With a battery input of ~11.1 [v] from a LiPo, I can't see an easy way to get this IC at 10[v] above the high-side source pin. (Unless I grounded it to the source pin(?), but then I'd imagine that the logic level inputs would probably not behave correctly.)

    I'm ruling this one out for a bldc motor controller and looking at three IR2101 high/low-side driver ICs. The turn-on/off times are also in the order of nanoseconds too.

    Many thanks for those tips!

    IR2101 datasheet:
    http://www.irf.com/product-info/datasheets/data/ir2101.pdf
     
  6. ronv

    AAC Fanatic!

    Nov 12, 2008
    3,292
    1,255
Loading...