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TLC59116 minimum power supply for 120mA

Egon Hirsch
Expert 3220 points
Other Parts Discussed in Thread: TLC59116

Hallo all,

 

My customer has several questions regarding our TLC59116.

 

What is the minimum power supply to achieve 120mA? What happened if the power supply voltage is too small to achieve the resistor programmed current?

Did the part generate an error message?

 

Customer wants to use the open circuit detection function to measure and detect open switches. What reaction speed is achievable with our part, if the customer uses a 400kHz I2C data stream?

 

Best regards

 

Olaf

  • 0
    TI__Expert 3460 points

    Hi Olaf,

    Figure 2 of the TLC59116 datasheet shows the output current in response to the output voltage.


    As for the open circuit detection, section 9.3.1 explains when the error is detected. If the output falls under these conditions, the Error register will detect the error. The reaction speed will be as soon as the open condition is met. 

    You will need to make sure that there is at least 1V on the output in order to avoid a false detection of an open load.

  • 0 in reply to Harry Kennedy1
    TI__Expert 3220 points
    Hallo Harry,

    yes my customer see figure 2 output current vs. output voltage. This is the reason for the question: What is the neccessary power supply for the LEDs to achieve at least 1V on the ouput? And if this power supply voltage is not high enough, for the programmed current, would this generates an error? This is an automotive application. During start up (cold cranck) this voltage could be not high enough.

    And if the part detects the open circuitry with the error register, how long does it take to bring this error to the output using a 400kHz I2C interface. Customer did not need an answer like "as soon as" he wants to know how many µs this needs.

    Special thanks for your efforts.

    Best regards

    Olaf
  • 0 in reply to Egon Hirsch
    TI__Expert 3220 points
    Hello Harry,

    my customer is still waiting for an answer. Did you have a chance to look at it, or should I forward my question to a different person?

    Best regards

    Olaf
  • 0 in reply to Egon Hirsch
    TI__Expert 3460 points
    Olaf,

    Sorry for the delay during the holiday. The necessary power supply for the LEDs is 1V above the LED forward voltage. As you reduce the voltage, the output current will change. The error will kick in when the output current is less than 0.5 times the target current. I would recommend at least 10us before the error can be detected.
  • 0 in reply to Harry Kennedy1
    TI__Expert 3460 points

    Olaf,

    If everything is okay, I'll close this thread.

  • 0 in reply to Harry Kennedy1
    TI__Expert 3220 points

    Hi Harry,

    yes, I think everything is o.k. You can close this thread.

    Special thanks for your efforts.

    Best regards

    Olaf