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LMG5200: High-frequency LED driver using GaN drivers.

Charles Nutter99418
Prodigy 80 points
Part Number: LMG5200

We wish operate the at 48VDC input to the final drivers and output 36V pulses at 45% duty cycle at minimum of 4 amps per pulse output into a toroidal HF planar transformer.  We noticed that the efficiency is not good at these levels. Are we missing something. Is there an alternative TI GaN driver?

We plan to use two units as a push-pull H bridge combination to create the 36-42 Volt pulse out at the pulse current of 4 amperes.

We are seeking at least 95% at the stated levels output to the transformer as intimated above. Is this feasible? 

https://www.ti.com/lit/ds/snoscy4e/snoscy4e.pdf?ts=1714068035844&ref_url=https%253A%252F%252Fwww.ti.com%252Ftool%252FLMG5200EVM-02%253FkeyMatch%253DLMG5200EVM

  • 0
    TI__Expert 4955 points

    Hi Charles, 

    It seems like the concern you mentioned above is with regards to efficiency. As you may know, losses in switching devices are characterized by switching losses and conduction losses. Switching losses are dependent on the application's switching frequency, and parasitic capacitance components of the device such as Coss and Cgs. Conduction losses are dependent on the rms currents and the device's on-resistance.

    Has a study been done to analyze what these losses would be? After this is done, a suitable device on-resistance is picked to find a balance between switching a conduction losses.  The LMG5200 is a 15mohm half-bridge. If your application is dominated by conduction losses, a smaller on-resistance would be recommended. If limited by switching losses, a larger on-resistance would be recommended. 

    If you determine that you require a smaller on-resistance for your application, we would recommend LMG2100, which is very similar to LMG5200, but is 4.4mohms.

    Best Regards,

    John