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TCA9539: How to control LEDs

Sadanori Kato
Guru 36540 points
Part Number: TCA9539

Hi,

Is my understanding as below correct when the I/O ports are used to control the LEDs at 3.3V for TCA9539 and 5V for the LEDs?

- LEDs are on
The I/O ports are set to the output and output to low.

- LEDs are off
The I/O ports are set to the input.

Best regards,
Kato

  • 0
    TI__Guru 62920 points

    Kato-san,

    Yes, your understanding is correct.  The LED can be turned off by configuring the Pn port as a high-impedance input so that current does not flow from the 5-V rail.

    If the LED and TCA9539 used the same VCC level then another option would be to configure the Pn port as a high-level output so that there is not a sufficient forward voltage across the LED.

    Please let us know if this is unclear or if you have further questions.

    Regards,
    Max

  • 0 in reply to Miguel Robertson
    Guru 36540 points

    Hi Max-san,

    Thank you for your response.

    I understand.

    Best regards,
    Kato