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About TLC59025

takahiko yokota
Mastermind 7135 points
Other Parts Discussed in Thread: TLC59025, TLC59116F

Hi

My customer uses TLC59025.
He has under two questions.
1.He doesn't use several　OUT terinal.
   So could you tell me the disposal method of OUT terminal not using?
2. He calculates dissipation power at Rext.
    So he needs the information about  Rext current, could you tell me it?
Best regards,
Yokota
  • 0
    TI__Expert 3460 points
    Hi Yokota-san,

    Thanks for asking these questions. For the TLC59025, the OUTx terminals can be left open if not used.

    The REXT pin should just have a resistor to ground (or open). We don't specify that current because it is dependent on the REXT resistor used. If the customer is concerned about the overall device power, they can look at the supply current spec in the datasheet. The typical and max values were taken with different REXT resistor values.
  • 0 in reply to Harry Kennedy1
    Mastermind 7135 points
    Hi Kennedy-san

    I'm sorry my understanding is wrong.

    Could you answer two questions once again?

    1. My customer uses TLC59025 under the condition the current of OUT terminal is different each.
        May he configure Rext in concert with max current?
    2. He needs the Rext current to select the Rext.
        If you have the information about Rext current, please tell me them.
    Best regards,
    Yokota
  • 0 in reply to takahiko yokota
    TI__Expert 3460 points
    Yokota-san,

    Could you please provide a schematic or block diagram? That will help me to better understand.

    2: Rext resistor can be a surface mount resistor. A typical 1/4 Watt resistor will do. The actual resistance value is based off the desired output current. this is written in the datasheet.
  • 0 in reply to Harry Kennedy1
    Mastermind 7135 points
    Hi Kennedy-san
    Thank you for the answer.
    I attached brief schematic.
    My customer uses TLC59025 changing the each current.
    Is this usage correct?
    If it is correct, do I adjust REXT to a maximum electric current?
    Best regards,
  • 0 in reply to takahiko yokota
    TI__Expert 3460 points
    Yokota-san,

    This operation is not possible with the TLC59025, but can be done with the TLC59116F. The REXT resistor sets the current for all 16 channels, so each LED would have 10mA.

    The TLC59116F doesn't use the REXT pin. The user will set resistors on the output to set the desired current. This will allow the customer to have a different current for each LED. This will require the user to use I2C instead of serial communication.