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TLC6C598-Q1: LED Current limiting resistor.

Dipali Thigale
Prodigy 20 points
Part Number: TLC6C598-Q1

Tool/software:

As per datasheet, each channel of TLC6C598-Q1 can draw max 50mA current.

Is it necessary to put Current limiting resistor in series of LED?

Power source to LED is 5V.

with absence of LED series resistor,  is there any change LED can draw current more than 50mA?

can I remove this LED to save space on PCB?

  • 0
    TI__Genius 11615 points

    Hi Dipali,

    The current-limiting resistor is necessary to set the desired current for each channel. See equation 1 in TLC6C598-Q1 datasheet.

    The internal current limit is set at 50mA per channel. Do you plan to drive each LED with 50mA?

    You must also consider the thermal performance and power dissipation.

    If you are relying on the internal current-limit of 50mA to set the LED current, about half of the power is dissipated inside the TLC6C598-Q1. For example, if your LED forward voltage is 2.5V with no external resistor, the internal power dissipation is 125mW per channel which is 0.875 watts with 7 channels active.

    The external current-limiting resistors set the current, but they also help dissipate heat away from the device.

    Regards,

    Zach

  • 0 in reply to Zach Olson
    Prodigy 20 points

    The internal current limit is set at 50mA per channel. Do you plan to drive each LED with 50mA?

    ==> No I wish to control the LED intensity by controlling PWM only.

    Is this device allows current flowing through LED more than 50mA in absence of resistor?

  • 0 in reply to Dipali Thigale
    TI__Genius 11615 points

    Hi Dipali,

    You must include a resistor to set the DC current per channel, as per equation 1. The PWM % duty cycle can then be used to control the LED brightness.

    Regards,

    Zach