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TCA9548A: USB HUB TCA9548A

Moshe Lerner
Prodigy 100 points
Part Number: TCA9548A

Hello

I'm using TCA9548AMRGER 8 port USB HUB with following conditions

VCC = 3.3V, SDA and SCL are connected through pull-ups to the 3.3V.

The master selects only one of the channels at a time.

Can I connect different voltages to the pull-ups of the channels? For example: ch1 pull-ups to 1.8V, ch2 pull-ups to 2.5V, and ch3 pull-ups to 3.3V.

The recommended operation conditions (see datasheet on page 4) defines: high level input voltage as 0.7*VCC and low input voltage as 0.3 * VCC.

Does it mean that that the pull-up voltage shall be equal to VCC?

Regards


   

  • 0
    Guru 317390 points

    Section 8.1 of the datasheet says:

    The TCA9548A may also be used for voltage translation, allowing the use of different bus voltages on each SCn/SDn pair such that 1.8-V, 2.5-V, or 3.3-V parts can communicate with 5-V parts. This is achieved by using external pull-up resistors to pull the bus up to the desired voltage for the master and each slave channel.

    Section 9.2.1 says:

    In an application where voltage translation is necessary, additional design requirements must be considered to determine an appropriate VCC voltage.

    The I²C pull-ups can be connected to any voltage that is at least as high as VCC. If you have 1.8 V I²C, VCC also must be 1.8 V.