• State
  • Locked Locked
  • Replies 1 reply
  • Subscribers 31 subscribers
  • Views 946 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TCA9548A 1.8V to 3.3V I2C conversion

Wenjun Huang
Expert 1770 points

I would like to ask about TCA9548 I2C switch with reset.

In the first pg of the datasheet, it says that it allows voltage-level translation between 2.5V, 3.3V and 5V buses under the Features section.

Under the Description/ Ordering Information, it say that this allows the use of different bus voltages on each pair so that 1.8V  or 2.5V or 3.3V can communicate with 5V without any additional protection.

I would like to ask if I could connect the SDA, SCL to a pullup resistor to 1.8V and my SDx, SCx, x=0-7 are pulled up to 3.3V. In this case, the VCC should be powered to 1.8V or 3.3V?

  • 0
    Expert 1770 points

    Was wondering if this chip TCA9548 allows voltage translation at all since it has only one VCC pin. In the datasheet, it writes that the input high voltage is 0.7*VCC whereas its input low voltage is 0.3*VCC.

    if VCC=1.8V, VIH=1.26V, VIL=0.54V

    If VCC=2.5V, VIH=1.75V, VIL=0.75V

    If VCC=3.3V, VIH=2.31V, VIL=0.99V

    If VCC pin is 3.3V, and SC0 and SD0 (I2C channel 0)  is 2.5V and I2C interface outputs 1.75V, the I2C MUX chip will only recognize 2.31V as high and 0.99V as low, hence it will think 1.75V is an unknown value. Is my understanding correct?