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TLC59116FIRHBR output question

David__
Genius 3585 points
Other Parts Discussed in Thread: TLC59116, TLC59116F

Hi, I'm new with the TLC59116FIRHBR LED driver.

I use 3.7V Li-ion Battery.

I use a white LED that has the following ratings.

Max Forward Voltage(Vf) = 3.28V, Max Forward Current(If) = 200mA
Vf == 2.69V when If == 30mA

V_LOGIC = 3V (I use BQ25010RHLR's output), VLED = 6V (I use TPS61089RNRR Boost Converter)

My questions are,

0) Is the OUT0~15 pins' output voltage is equal  VCC(TLC59116FIRHBR's pin 27, in this case, 3V) when it is HIGH,

0V when LOW?

Or is it programmable via I2C?

1) I connected a 360 Ohm resistor to the REXT pin. Does this limit the OUT0~15 pins' currents?

I'm confused about the REXT pin. What does that do?

-Best Regards, David

  • 0
    TI__Expert 3460 points

    Hi David

    Thanks for the question. First, the I2C will turn a channel on or off. Each of the channels are an open drain output that allow current to flow only when the channel is enabled. When the channel is on (LED is turned on), the OUTx pin voltage become VLED - Vf_led. When the channel is off, no current will flow, and the output will be a floating node.

    The REXT pin sets the reference current for each of the outputs. This is detailed more in the datasheet under the "Typical Appliations" section. You will use the REXT resistor to set the LED current to the desired value.

    Hope this helps, 

  • 0 in reply to Harry Kennedy1
    Genius 3585 points
    Thanks, Harry.

    However, I couldn't find the contents related to "REXT resistor to set the LED current to the desired value" in the datasheet.

    As you see my posted schematic, I use 360 ohms as the REXT resistor value.

    In this case, how much current is drawn from the output pins?

    -Best Regards, David
  • 0 in reply to David__
    TI__Expert 3460 points

    Hi David,

    The TLC59116 has two version: TLC59116F and TLC59116I. You are actually referring to TLC59116I where the REXT values sets the current for all of the channels.

    I've attached images of the Typical Application section for future reference. The section details the math behind it, but the equation is that Iout_target = (1.25V / REXT) *15. with 360Ohms for REXT, you will see 52mA as the Iout current.

  • 0 in reply to Harry Kennedy1
    Genius 3585 points

    Harry Kennedy1 said:
    I've attached images of the Typical Application section for future reference.

    Thanks, Harry. However, the attached images don't appear on my screen. Can you check your attachments, please?

  • 0 in reply to David__
    TI__Expert 3460 points
    David,

    Here's a link to the datasheet
    www.ti.com/.../tlc59116

    You can look at section 10.2 to check the typical application.