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UCC27531: UCC27531 an UCC27201 Application Question

Wen Yung
Expert 1220 points
Part Number: UCC27531
Other Parts Discussed in Thread: UCC27201

Hi Sir,

I use TI gate driver and MOSFET simulation DC Motor drive application power tool now.

I have two topology survey UCC27531 and UCC27201.

Since use Half Bridge driver motor, have MOSFET burn damage issue, I guess maybe MOSFET current rating not enough(just use one pcs).

I think change to Low side driver motor and parallel MOSFET. Could you provide suggest comment for me? Thanks.



Half Bridge

Low Side


  • 0
    TI__Genius 9130 points
    Wen

    I have asked one of my colleagues in the drivers team to look at your question. You should get a response in the next day or two.

    Thanks,
    Bernard
  • 0
    TI__Intellectual 2910 points

    Wen Yung,

    I have looked at both circuit schematics you provided.

    For a mono-directional motor application I have most commonly seen the single-ended, low-side approach. If you go with this approach, a diode in parallel with the motor must be added, with the cathode connected to BAT_18V. This diode will provide a safe path for the inductive kickback of the motor back to the battery.

    Regarding understanding why the half-bridge circuit resulted in MOSFET failures, I have some suggestions of where to look. First of all, ensure the design's current needs fit within the continuous current rating for the selected MOSFET. This applies also for the low-side drive approach. Next, I would be concerned with the boost supply. Look at it with a scope and verify that HB-HS is reaching the desired voltage and keeping it rather constant. Also ensure that HB-HS reaches at least 12V in order to best turn on the high-side FET (for best performance, based on examining the FET datasheet pg 1). What is the (ground-referenced) output voltage of the boost converter? Ensure that the boost output is present and stable before applying a turn-on signal at the HI/LI pins. If the HB-HS voltage is too low, the high-side switch will either not turn on, or might turn on in the linear region, causing much higher conduction losses/heat. At what frequency is the boost converter running? Is the motor being pulse-width modulated, or just running in 100% ON or OFF mode? If PWM, please share also what frequency and the phase shift between motor PWM vs the boost converter.

    In either design, ensure the gate drive series resistors are sized for fast turn-on of the FETs. If the resistance is too high, the FET turn-off will be slow and will cause increased switching losses.

    Also ensure that bypass capacitors are used for both the HB supply and the VDD pin of the driver. The initial burst of charge used to turn on the FETs is sourced by these capacitors. Refer to the driver datasheet for cap selection and placement recommendations.

    I hope this post helps get you going.

    Regards,

    - Daniel

  • 0 in reply to Daniel Ruiz
    Expert 1220 points
    Hi Sir,

    Thanks for your clearly comment.

    Wen