Because of the holidays, TI E2E™ design support forum responses will be delayed from Dec. 25 through Jan. 2. Thank you for your patience.

  • State
  • Locked Locked
  • Replies 5 replies
  • Subscribers 65 subscribers
  • Views 632 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

48V 8A LED string solution?

Paul Schoenke
Expert 1375 points
Other Parts Discussed in Thread: UCC28811, LM3409HV

Hello:

Our customer needs some way to control current through a very long LED string.  It may have to handle up to 8A.  They’ve been looking at switching supplies that could be used in current control mode – not sure what else is out there.  They’ve tried using the TI WebBench tool, but it does not offer anything that controls LED current / brightness over 2A.  A high current / high output voltage switching supply might work.  They need to drive 48V to this LED light string. 

The LEDs are selected.  They are on a separate board that they’ve been running for a long time.  They’re using Avago 1W LEDs currently.  They’ve had some thoughts about going to 3W.  Maybe a bit down the road.

There are 12 LEDs per serial string.  They can connect a LOT of these in parallel, requiring a lot of current.   

Any feedback or input with respect to a solution is welcomed and appreciated!

Thanks again!

Paul

  • 0
    Prodigy 5 points

    What is the input voltage range and do they need dimming?
    If dimming then analog or pwm and what dimming range is needed?

  • 0 in reply to Ed Walker
    Expert 1375 points

    Thanks Ed!

    Input voltage range is pretty much 48V – probably a small band – 47 – 49V. 

    It does need dimming actually.

    Thanks again!

    Paul

  • 0 in reply to Paul Schoenke
    Prodigy 5 points

    Hello Paul,

    So you want to drive a 48V LED string, perhaps multiple strings, at up to 8 amps total, from a 48V input. 8Amps at 48V is 384Watts.

    I think this this would require multiple stages, since you need to get a source voltage above the LED string voltage. I show a PFC stage but for now consider it just a boost.
    The first example below shows a PFC boost input, ISOLATION stage, and CURRENT drive stage.
    If you don’t need isolation you can remove that stage.

    The second example below shows a PFC boost input, ISOLATION stage, and CURRENT drive stage.
    Basically the same as the first example.

    The third example below show a PFC boost input, CURRENT drive stage, then ISOLATION stage.
    This is an interesting topology, current transformers are used at the last stage.
    You control the current with UCC28811 buck, send that into a PUSH PULL transformer with multiple output windings. Remember current in the transformer is a function of the turns ratio, so if you control the current in the primary then you are directly controlling the current in the secondaries.
    It’s called MULTI TRANSFORMER led driver.
    There is a reference design on the web: http://www.ti.com/tool/pmp4302a

    Also see this: http://www.ti.com/solution/lighting_multi_string_led_driver for some basic block diagrams and ideas.

  • 0 in reply to Ed Walker
    Mastermind 9752 points

    I have a similar application - 48V @ 3.6A per string and will likely use the LM3409HV. Take a look at the dev board for this IC; it's fairly simple. Depending on your product volumes you may want to use a pre-certified, off-the-shelf AC to 48VDC power supply like those available from Meanwell etc. They cost about $100 for the 500W version.

    Also, Ed, I'd like to get one of these LM3409HV Dev boards to try out. I used to be able to get stuff like this from our TI rep but no more reps makes things harder.

    --Derek

  • 0 in reply to Derek
    Prodigy 5 points

    Derek, you can order this board from its folder on the TI web: http://www.ti.com/tool/lm3409hveval 

    TI's Authorized Distributors have take the place of TI "REP" firms.
    They provide excellent support.
    Depending on your location our Distributors may be found at: http://www.ti.com/general/docs/distributorinfo.tsp 


    From the link I provided you can find the below information on ordering.

    Order Now

    Part Number Buy from Texas Instruments Buy from Authorized Distributor Status Lead-Free   RoHS  

    LM3409HVEVAL/NOPB: LM3409HV High Voltage LED Buck Controller Evaluation Board

    		 $79.00(US$)

    In Stock Ships in 24 to 48 hours
    Pricing may vary.

    		ACTIVEYes  Yes  
    Contact a Distributor
    - Select a location - Argentina Australia Austria Belarus Belgium Bolivia Bosnia-Herzegovina Brazil Bulgaria Canada Chile China Colombia Croatia Czech Republic Denmark Ecuador Egypt Estonia Finland France Germany Greece Hong Kong Hungary India Ireland Israel Italy Japan Latvia Lithuania Luxembourg Macedonia Malaysia Mexico Moldova Netherlands New Zealand Norway Paraguay Peru Philippines Poland Portugal Romania Russian Federation Saudi Arabia Singapore Slovak Republic Slovenia South Africa South Korea Spain Sweden Switzerland Taiwan Thailand Turkey Ukraine United Arab Emirates United Kingdom United States     Armed Forces the Americas     Armed Forces Europe     Alaska     Alabama     Armed Forces Pacific     Arkansas     Arizona     California     Colorado     Connecticut     District of Columbia     Delaware     Florida     Georgia     Hawaii     Iowa     Idaho     Illinois     Indiana     Kansas     Kentucky     Louisiana     Massachusetts     Maryland     Maine     Michigan     Minnesota     Missouri     Mississippi     Montana     North Carolina     North Dakota     Nebraska     New Hampshire     New Jersey     New Mexico     Nevada     New York     Ohio     Oklahoma     Oregon     Pennsylvania     Puerto Rico     Rhode Island     South Carolina     South Dakota     Tennessee     Texas     Utah     Virginia     Vermont     Washington     Wisconsin     West Virginia     Wyoming Uruguay Venezuela Vietnam