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BQ500511: LED current

na na78
Guru 16770 points
Part Number: BQ500511
Other Parts Discussed in Thread: BQ50002A,

Hi

1.

According to the datasheet, it is offered that LED_A/B/C pins are connected to LED via 1Kohm resistor.

Is it possible to use a resistor smaller than 1Kohm?

2.

What is the maximum output current for LED_A/B/C?

BestRegards

  • 0
    TI__Guru 65746 points
    The 3.0V supply in bq50002A is limited, this is only a 14mA LDO, BP3 at pin 4. This is the source of current to drive the LEDs. Recommend using the 1k ohm resistor or driving the LED with an external supply for more current.
  • 0 in reply to Bill Johns
    Guru 16770 points

    Hi Bill

    Thank you for your reply.

    Sorry, the device of my question is bq500511.
    And I want to confirm the meaning of the following description.

    Datasheet, P.8 7.3.3 LED Modes
    www.ti.com/.../bq500511.pdf

    "The bq500511 can directly drive three LED outputs (pin 11, pin 12, and pin 14) through a simple current limit
    resistor (typically 470 Ω), based on the mode selected. The three current limit resistors can be individually
    adjusted to tune or match the brightness of the LEDs. Do not exceed the maximum output current rating of the
    device."

    Can we select a resistor value other than 1kohm to adjust birhtness of LEDs?

    And that value is limited by 2mA, is it correct?

    BestRegards

  • 0 in reply to na na78
    TI__Guru 65746 points

    The bq50002A is the power supply for bq500511, 3.0V LDO that is limited to about 14mA.  The additional current to drive LED will come from this supply.

    If you increase LED current slightly that will problem not be a problem.

  • 0 in reply to Bill Johns
    Guru 16770 points

    Hi Bill

    Thank you for your reply.

    >The bq50002A is the power supply for bq500511, 3.0V LDO that is limited to about 14mA.  The additional current to drive LED will come from this supply.

    I understand it.

    Finally, can you tell me the following as a supplement?

    Is the following absolute maximum ratings applied to LED output pins of bq500511?

    If yes, I will regard the LED output current is 2mA when I explain it to customer because 2mA is guaranteed.

    BestRegards