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Looking for a suitable LED driver

Jenny Lu69
Expert 1810 points
Other Parts Discussed in Thread: LM3445, TL494, LM3444

Hi sir,

I am looking for a suitable LED driver, my design requirements is followed:

input: DC 36-100v

output: 300watts. It could be 30v@10A; or 48v@6.25A, or 30V/2A with 5 channels; or 48V/1.25A with 5 channels.

I didn't find a solution on www.ti.com, Could you recommend me a suitable solution? Thanks a lot!

Regards,

Jenny

 

  • 0
    TI__Genius 14295 points
    Hi, Jenny,

    From your requirements, I move this thread to LPP.

    Thanks.
    Regards,
    Kenneth
  • 0 in reply to Kenneth Du
    Expert 1810 points

    Hi Kenneth,

    Sorry, did i mistake the forum? And I want to know when i can get the answer, i am a somewhat anxious. Thanks a lot.

    Regards

    Jenny

  • 0 in reply to Jenny Lu69
    TI__Mastermind 28655 points

    Hello Jenny,

    Yes you can do this with theLM3445.  It's original design intent was for low power triac dimming from 120 or 200/230/240 VAC but it's a fairly simple controller that can do this as well.  We do not have a design for this power level to share but it has been done by others.

    Things to watch for at this power level are the Qgate of the MOSFET used.  The gate drive wasn't intended to directly drive MOSFETs for 100's of watts of output power and may require an additional gate drive IC.  Being this is 100 volts and below there are MOSFETs that can be chosen to do this depending on the switching frequency range you are planning to use.  Another is the freewheel diode.  Most designs using the LM3445 as a buck converter run continuous mode meaning the the MOSFET must recover the freewheel diode.  Again at 100 volts and below there should be many suitable freewheel diodes available.  A schottky diode is almost always a good way to go since the diode recovery is a capacitance.  There are also some ultra-fast recovery diodes that will work as well.

    I don't know what you plan on using for an inductor, it will be fairly large or a custom due to the power level and trying to keep the switching frequency not too high.

    Regards,

  • 0 in reply to Irwin Nederbragt
    Expert 1810 points

    Hi Irwin，

    Thanks for your good answer and apologize to my late reply.

    Yet, I found TL494 can meet my design recently, I want make it implement a LED driver. Do you have some relevant reference design about it? Thanks very much!

    Regards,

    Jenny

  • 0 in reply to Jenny Lu69
    TI__Mastermind 28655 points

    Hi Jenny,

    The TL494 could do this if you know how you want to configure it.  It is an older part that is intended to be a configurable PWM controller.  This part is for the person that wants to create their own PWM controller from the internal building blocks.  If you know how you want to set up your controller you can go this route.  There is a lot of information regarding this part on TI's website but not as LED current regulators. 

    There are newer specifically designed to drive LEDs as current regulators, the LM3445 is one, the LM3444 is a feature removed LM3445 that may be better for your application.  There are other parts as well.  Are you planning or relying on the LED strings to share between themselves in your parallel configuration?

    Regards,