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LED driver

Calum Mackinnon
Genius 4155 points
Other Parts Discussed in Thread: TLC59116F, TLC59116FEVM-571, TLC5949

Hi,

I am working on a project that needs an LED driver.  If you can help or point me in the right direction I would appreciate the help.

I like the constant current sinks in the TLC594x and TLC59116F family of parts but I am going to have some questions and will get an EVM to borrow and play around with.

I see that TLC59116FEVM-571 is available are any of the TLC594x EVM boards going to become available too.

Here are some specs on what I need.

  • 12-14 channels (strings)
  • 30mA per string
  • 10.2V peak voltage per string, 9.15V typical.
  • Need brightness control such as PWM.
  • Low Control Voltage
  • Small package QFN24 would be nice.
  • Battery operated  ( 4400mAh 7.4V Battery )

I would like to keep the voltage headroom as low as possible to keep the power down.  This means the current sink pins need to have a low regulation voltage.  A lot of these parts aren’t exactly clear on this point as to what the voltage is although many of them seem to want about 1V.  With 14 channels 100% duty cycle at 30mA and 1V control voltage on each current sink pin that is 0.42 W.   Would like to get that down.

  • 0
    TI__Intellectual 950 points

    Hi Calum,

    Most of TI's LED driver is 16CH, of course, also have 24CH and 48CH. Most of them can support 30mA. If you need PWM control, just choose a PWM part, such as TLC594X. This family are all 16CH PWM LED driver.

    For the requirement of LOW control voltage, you can get the information from V-I curve in datasheet. In fact, the minimum control voltage will change with the sink current.For our lastest part, it can support 0.22V @10mA.

    Hope it is useful for you.

     

  • 0 in reply to Rosley Ge
    Genius 4155 points

    Thanks,

    If I look at the TLC5949 as an example - I'm looking at Fig 13 output current v output volatge. The test conditions for this graph are.

    Vcc = 3.3 V

    BC = 7Fh

    Voutn = 0.8 V

    TA = +25 C

     If VoutN is set at 0.8V as the test condition(I assume that's the volatge on the 16 OUT pins)-  what is the output volatge along the x axis in te graph telling me?

    Cheers

    Calum

  • 0 in reply to Calum Mackinnon
    TI__Intellectual 950 points

    Hi Calum,

    It is a little confusing. Voutn = 0.8V means other channels except the measured channel is set to 0.8V. The measured channel change from 0V to 3V. So you can get pin voltage in this graph.

    Cheers,

    Rosley