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TCA8418 lowest power mode.

Chris Amos
Prodigy 10 points

I wonder if you can recommend the settings I could apply to reduce the consumption of the chip to a minimum, my device has an unrecoverable (except by power cycle) shutdown mode, I do not need the keyboard anymore in this mode so want to shut the device down.

The datasheet mentions a standby current of 3 uA, how do I get near that, for instance how do I turn of the oscillator which the data sheet shows might eat up 8 uA (table 6.5)?

  • 0
    TI__Genius 16510 points
    Hello Chris,

    Thank you for the question!

    The best way to achieve low power usage is by :
    1) Set any ports that are not tied to ground normally to input with pull up resistors enabled (Done by setting appropriate ports in GPIO_DIR1/2/3 0x23-0x25 to 0 for input, and resistor control done in GPIO_PULL1/2/3 registers 0x2C-0x2E set to 0 to enable pull ups)
    2) Disabling keyscan mode. This is achieved by setting all key scan registers (0x1D, 0x1E, 0x1F) to 0x00.
    3) Making sure all interrupts are cleared, and if you don't care about any further key presses, disable interrupts (then the INT pin wont go low, causing extra current path from the pull up resistor to ground).

    The oscillator is controlled by the logic and cannot be shut off by you. If you can disable interrupts and keyscan, that is your best bet to getting the oscillator to low power mode.