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TIDA-00795: Bi Directional Switch using N-Channel MOSFET

Timothy Lund
Prodigy 20 points
Part Number: TIDA-00795
Other Parts Discussed in Thread: UCC27282, SN6501

I'm looking for a N-Channel MOSFET gate driver that can drive 2 N-Channel MOSFETs in series and allow for bi-directional current flow. See SLVA948 figure 13 for reference. All of the gate drivers I could find have reverse voltage protection which shuts the MOSFETs off in the event the output voltage is higher than the input. The input voltage is an industrial 24V so 40V is needed to allow for transients. The mosfets themselves will have a max steady state current of 15A. I'm planning on using the INA302A to regulate current and it will be DAC controlled. Any ideas on how I could drive the 2 series N-Channel MOSFETs?

  • 0
    TI__Mastermind 21685 points

    Hello Timothy,

    Thank you for the interest in TI products. Can you clarify/confirm your circuit and requirements further?

    Are you wanting to drive two back to back MOSFET's with a common source connection? Are the MOSFETs on the high voltage side of the input (not ground referenced)?

    There are integrated solutions such as the LM5050 that can work in this configuration, depending on the MOSFETs and desired switch response times.

    If the LM5050 does not look adequate from a driver strength standpoint, post another question on this thread and we can suggest other solutions.

    Regards,

  • 0 in reply to Richard Herring
    Prodigy 20 points

    Hi Richard,

    Thank you for your quick response. Yes I'm looking to drive back to back MOSFET's that are connected by their source pins. These MOSFETS are on the high side (not ground referenced) and will be used as a high side switch that allows bi-directional current flow. Power would be connected to the drain of MOSFET #1 while the load would be connected to the drain of MOSFET #2.

    I want to emulate the following example but with N-Channel instead of P-Channel MOSFETS. I just can't figure out how to drive them without causing the reverse voltage protection to kick in on most driving circuits.It looks like the LM5050 also has a reverse voltage protection.

    Do you have an example of how I could use it to drive back to back MOSFET's? Is there another one you'd recommend given a better idea of what I'm trying to do?

  • 0 in reply to Timothy Lund
    TI__Guru**** 189399 points

    Hi, Timothy,

    Richard is out of the office today. He will be back next week and get back to you.

  • 0 in reply to Don Dapkus
    TI__Genius 13445 points

    Hello Timothy,

    Thanks for your interest in our drivers, I work with Richard and will help suggest a solution while he's out. 

    From the schematic and your description, it sounds like you're looking for a dedicated high-side driver to drive the back-to-back N-ch FETs to connect/disconnect the load. 

    Though we don't currently have a dedicated high-side driver, you might consider using the high-side of one our half-bridge drivers to drive the FETs in the following configuration using UCC27282:

    -This solution will require a dedicated floating bias (for the high-side to drive the b2b FETs at high-duty cycle) consisting of SN6501 + transformer for long duty cycle operations.

    - The driver high-side has a UVLO of 4.4V which the floating supply will maintain above that threshold. 

    -Gate drive operation specified at 5.5V to 16V.

    -2.5A/ 3.5A peak drive current sufficient to drive high gate charge FETs to ensure minimal response time from the driver + FETs.

    Please let us know if you have additional questions.

    Regards,

    -Mamadou