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Original question:

PCA9518: About Vilc - Vol @PCA9518

PCA9518: Does support 2.8V pull-up?

Liu Yang
Expert 8745 points
Part Number: PCA9518
Other Parts Discussed in Thread: PCA9306, TCA9517

Hi team,

From P6 of the data sheet, it means that VIH=0.7*Vcc-5.5V. If Vcc=3.3V, VIH=2.31-5.5V so it seems that there is no problem using 2.8V.

However there is the following description in P3 of the data sheet,

“The device is designed for 3-V to 3.6-V VCC operation, but it has 5-V tolerant I2C and enable (EN) input pins.
This feature allows for translation from 3 V to 5 V between a master and slave.”

I2C(SDAx/SCLx) and EN pin can operate at 3-5V, that is, 2.8V pull-up cannot be used. Is it correct?

If we are trying to connect an IC that requires 2.8V pull-up and if PCA9518 does not support 2.8V pull-up, we need to prepare a level shifter, so I've confirmed it just in case.

Beat Regards,
Tom Liu

  • 0
    TI__Guru 72751 points

    Hey Tom,

    For a level shifter device have you considered PCA9306?

    If you need to redrive a signal then TCA9517 would also be suitable for a level shifter with buffering capability.

    If you are need to use PCA9518 (which may be overkill for some applications) then using 2.8V pull up resistors on the SDA/SCL pins is okay while Vcc is 3.3V. What you may see is some minor increased supply current but I would still expect normal functionality.

    -Bobby