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PCA9548A: PCA9548A with 1.8v or TXS0108

Frank Xiao
Genius 12055 points
Part Number: PCA9548A
Other Parts Discussed in Thread: TCA9548A

Hi team,

We want to check whether the PCA9548A can support the two structures below. structure 1, remove the TXS0108 circuit and just connect the PCA9548A to 1.8v side with 4.7k pull up resistors, but the high voltage will be 2.12v and rising waveform has the return curve. Whether the device can be used for 1.8V condition and whether it has risks? Why the waveform is like this?

Whether we can use the above structure with TXS0108 for the requirement as the structure 2, if we connect like this, the TXS0108 left side also has the return curve. What's your opinion? Thanks. 

  • 0
    TI__Mastermind 26736 points

    Frank,

    Thanks for reaching out!

    Let me first clarify that the supply voltage must be at least 2.3 V for the PCA9548A. Please allow me to strongly recommend using the TCA9548A instead, which allows supply voltages as low as 1.65 V and also has newer technology. It is a pin-to-pin drop-in replacement for the PCA9548A that has better performance (and lower cost!).

    I am not totally sure I understand your structures. Do you mean you will have the I2C bus voltage divided between 1.8 V and 3.3 V? Additionally, I am not sure what your layout is for structure 2, unless you mean that the diagram you provided is exactly structure 2. If this is the case, why is TXS0108 shorted?

    Would it be possible to change to the TCA9548A?

    Best,

    Danny

  • 0 in reply to Danny Bacic
    TI__Genius 12055 points

    Hi Danny,

    We can try TCA9548. Thanks.