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LP8864-Q1: Multi channel LED driver with high dynamic range

Part Number: LP8864-Q1
Other Parts Discussed in Thread: TLC5971, TLC5940, TPS92515

Tool/software:

Hi there, in the past we had a representative directly assigned to us, but I guess now we should use this forum!

We are starting a new design for a new familiy of product. We are looking at diffrent led driver to fullfill our list of specifications. I looked at the LP8864-Q1 and it seemed perfect...until we found out that we can't control all 4 channel independantly!

Our design needs looks something like this:

  • 12 channels total per board (can be multiple chips)
  • > 10000:1 total dimming contrast (analog + digital)
  • > 12khz PWM digital dimming (flicker free)
  • < 3% current error from channel to channel/chip to chip
  • Maximum current around 200-300mA (not all channels would be pushed at the same time to maximum current)
  • Led string voltage will be around 24V

Our design specs are kind of hard to meet, but if somebody at T.I. could help us look at what's possible with T.I. chips it would be greatly appreciated. If all but one criteria can be achieved with a chip, it's worth looking into it!

I would love to use the filter on the website, but unfortunatly we can't filter by PWM dimming frequency, maximum contrast ratio or error between chip!

Thanks in advance

  • Hi William,

    Our expert is out of office and will feedback to you later.

    BR, Gracie

  • HI, William

    May I ask what is the EE of your design?

  • Hi,

    The design is not done yet. We are in the chip selection phase and for now I am the one working on it. That said, there might be some of my colleagues that will be involve in the near future.

  • As of now I have looked into:

    TLC5971 : Not a good option because PWM dimming  is less than 150hz, but I liked the +/- 1% error from chip to chip

    TLC5940 ; This one is a bit better in terms of PWM frequency because it is "only" 12bits, up to 7khz with external clock if I remember correctly. Typical 2% error but 4% maximum. Don't like the fact that I would have to route a 30Mhz all over the board.

    3x TPS92515 with 1x TPS92662: This one might give us very high dynamic range, but we know that TPS92515 will need calibration if we want small error between board (we use that chip a lot lately). That solution will probably end up taking too much space and costing too much.

    TPS92682 : this might be interesting, it looks like 2x TPS92515 or similar into one package with digital communication. Internal PWM is only 1khz, but could be using external PWM. Probably too much space needed on the board and cost is also probably an issue (would need 6 chips per board).

    I've also looked at other led driver manufacturer. One option that we might investigate is using a MCU with very high resolution PWM (250mhz clock) connected to a linear driver chip with 250mA capabilities. Not sure about the high dynamic range when using a high frequency PWM on a linear led driver.


    So as you can see we are in the brainstorm phase. Nothing is yet decided. We will probably investigate more deeply two or more options before we settle on a solution.

  • Hi, William

    Could you pls take a look at LP8863? It can control the channel independently and for 200-300mA requirement, It can combine two channel to achieve this.

  • Thanks a lot! Exactly what we needed. I visited this product page and I saw that it was again marked as "backlight driver" so I thought it was just like the LP8864 and you can't control channel independantly. Your intervention was crucial in our chip selection!

    This is amazing.

  • Hi, William

    Glad to help you, and pls let me know if you have any other questions.