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LSF0102: The signal pin pull up resistor value question

Paul Yeh
Genius 16185 points
Part Number: LSF0102

Hi team,

My customer design LSF0102 level shift device for I2C interface application.

They would like to check with us is 1.5kohm pull up resistor ok or not?

The I2C speed is 400kHz.

Please confirm.

Thanks

  • 0
    Guru 317000 points

    The LSF itself does not care.

    The value of the pull-up resistor must be balanced between maximum speed and power usage, and is limited by the drive strength of all I²C devices. (Please note that the resistors on both sides act in parallel; can your 1.8 V easily drive 3.4 mA?) I²C is very slow, so you can probably use higher values like 10 kΩ.

    The actual speed limit depends on the total capacitance of the I²C lines. This is hard to estimate; check the waveforms with an oscilloscope.