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recommendation for efficient led drver

or sam
Expert 2020 points

Other Parts Discussed in Thread: LM3405, LM337, TPS60250, LP5521, LM8502, LP5560

Hi

I would like to get recommendation for most efficient driver for low voltages (3.3V) to controll 1 led using I2c,pwm,spi or any kind of digital communication, the max needed current is 200 mA but efficient is needed becuse it is working on batteries.

Thanks

  • 0
    TI__Mastermind 25976 points

    so you need a buck led driver...

    the "closest" device to your needs seems to be the LM3405

    Vincenzo

  • 0 in reply to Vincenzo Pizzolante
    Expert 2020 points

    hi

    this is not good for my application.

    I need controllable led driver I want to control the current because I measure the amount of light from the led. the PWM dimming you recommended is problematic because it is on and of and not controll the current.

    in addition I also need something with the same demand for 40mA.

    thanks 

  • 0 in reply to or sam
    TI__Mastermind 25976 points

    ok, in this case you can then use an LDO in current source configuration.

    something normally made with an LM337

    Vincenzo

  • 0 in reply to Vincenzo Pizzolante
    Expert 2020 points

    Hi

    this in to good as well, please read the first post it should be digitally controlled.

    sorry for the mistake in the first post the current is 20mA not 200mA as was written...  

    what about:

    TPS60250?

    Regards,

  • 0 in reply to or sam
    TI__Intellectual 2510 points

    Hi,

    When I first read this post I thought you want a very simple driver that drives only one LED output with current output 0-200 mA or 0-40mA, but with the TPS60250 it seems that you could settle for 25mA/output (or 80mA with 4 level dimming) and the device could have more than one output?

    I browsed through and found TLC5970. Would that be suitable for you? The maximum current is controlled with external resistor (max curren capability is 150 mA/channel). There is a 7-bit dot correction in the device.

    Then there is devices like LP5521, which has three LED outputs with 25.5 mA maximum current. Device has 8-bit PWM and 8-bit current control.

    More complex device is LM8502 where there are 9 LED outputs and 2 flash LED outputs. LED output maximum current is adjusted with bit selection (3/6/12.5 or 25.5mA max) adn there is 8-bit current control with the selected maximum. Flash current is with 37.5 mA stepping from 37.5 to 600 mA and torch current is from 18.75 mA to 150 mA with 18.75 mA step.

    Regards,

    Sami

  • 0 in reply to Sami Kotijarvi
    Expert 2020 points

    Hi Sami 

    1. I can settle for 25mA (200 is a mistake I made). as for more then 1 output I prefer 1 output but if it doesnt exist I would not use all the ports.

    2. yes it seem to do the work although I need to build the protocol for SCKA and SCKB so I prefer to use more known protocols... 

    3. this also seem to be good.

    why dont you recommend on the tps60250? 

    thanks,

  • 0 in reply to or sam
    TI__Intellectual 2510 points

    Hi,

    I am not saying that TPS60250 would not be a good fit to your application. I was just offering you other choices in case you want smaller pin number. Also I am more acquainted with LP5521 than TPS60250. So feel free to choose what ever suits the best your application.

    In our group we have one product for driving 1 LED output (LP5560), but it is driven directly from battery. This device has only 4 pins (VDD, LED, GND and CTRL). There is a single-wire interface and the LED current is adjustable (3-bit) from 2.5 mA to 20 mA with 2.5 mA step. This is in a micro SMD package. To let you know in case the package is a limitation in your application.

    Regards,

    Sami