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LED driver 48V 20A

Stefano Zanotti
Prodigy 70 points
Other Parts Discussed in Thread: TPS92640, TPS92641

We need to design a LED driver board for Vin 24V-48V, Vout <= 24V, Iout <= 20A, with Iout dimming and 0-10s soft-start.
For the dimming and soft start, we can design external circuitry to drive a PWM dimming and/or an analog dimming pin from the LED driver IC, though a direct support from the LED driver IC (only needing an external trimmer or voltage divider) would be great.
It would also be great to have an evaluation board supporting such voltage/current, or guidelines on the selection of the power MOSFETs.
Thanks

  • 0
    TI__Mastermind 25500 points

    Hello Stefano,

    For this much current your best choice would be the TPS92640/TPS92641. They are synchronous buck controllers and it looks like they have the features you need. There is no high current EVM available, but there is a 20A reference design at:

    You would need higher voltage ratings for the caps and FETs for your application, but otherwise it is very close to what you need. You generally do want to lower the switching frequency for higher voltage applications for thermal reasons (AC losses are proportional to Fsw and V^2).

    As for FET selection you generally just need a high enough voltage rating and then try and get the lowest Rds(on) you can in a FET with low enough gate charge that the device can drive it effectively. Each FET will require Qg*Fsw of current from the chips VCC supply, so the total needs to remain below the VCC current limit.

    Regards,

    Clint

  • 0 in reply to Clinton Jensen
    Prodigy 70 points

    Thanks for the information. It seems very interesting, and we're going to look into it.