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TLC59282: TLC59282

Winston Rodrigues
Prodigy 60 points
Part Number: TLC59282

Hello,

    I have a quick question about TLC59282.

OUT0 to OUT15 ins are for LED sink. 

for example if  I have below values: 

    Vdd = 5v

    Vled = 5v

    Iref = 20ma

   Rext = 2.55K 

  LEDs forward voltage is 2.2v

  Then do I need to add limiting series resistor through LED to OUTx pin of the chip  ? 

  Is my schematic attached is correct ? 

  • 0
    TI__Genius 14295 points

    Hi, Winston,

    Your schematic is correct.

    The biggest consideration is thermal performance.

    Considering using 20mA for all channels all the time, the power dissipation of TLC59282 is around:

    (5V-2.2V)*20mA*16=0.896W.

    If using QFN package, the θJA=46.8°C/W, the temperature increase is 0.896*46.8=42°C.

    If the duty cycle is less than 100%, the temperature increase is less than 42°C.

    To decrease the power dissipation, you can decrease the voltage drop on TLC59282 by adding a resistor.

    For example, adding 100ohm resistor can decrease the voltage drop on TLC59282 to 5-2.2-100*0.02=0.8V.

    Thanks.

    Regards,

    Kenneth

  • 0 in reply to Kenneth Du
    Prodigy 60 points
    HI Kenneth,

    Thanks for the info :).

    Consider the scenario:

    LEDs are going to be ON for 1ms. and OFF for 15ms. (refresf rate 62.5Hz).

    which means the duty cycle is 6.25% . Then do you think the series resistor is necessary ?
  • 0 in reply to Winston Rodrigues
    TI__Genius 14295 points
    Hi, Winston,

    In such case, there's no need to add resistor.

    Thanks.
    Regards,
    Kenneth