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TCA9803: TCA9803 over TCA9406

Ohad Bonneh
Intellectual 790 points
Part Number: TCA9803
Other Parts Discussed in Thread: TCA9406

Hi Team, 

I need a simple voltage translator for I2C.

I was looking at the TCA9803. Side B of the device has current source that is always active. I verified the connected device leakage and it seems Okay but I want to be safe.

I saw the TCA9406. Does it recommend for new designs?

What is the advantage of using the TCA9803 over TCA9406? Why TCA9803 side B was designed with current source?

why do we even design translators with current source?

Best regards. 

  • +1
    TI__Mastermind 25961 points

    Hey Ohad,

    You are right that the TCA9803 is capable of translating, but also note that the main use case is for buffering (separating I/O capacitance so the loading condition can be >400pF per the I2C standard).  This internal current source on B side is always on- while the device measures this current to determine if an external device is pulling down the bus or not. 

    The TCA9406 on the other hand, is an I2C voltage translator with internal 10k pullup resistors so externals are not needed. The device also has built in RTA to help w/ data rates. 

    For more devices used for I2C translation, see section 4.1.2 of this app note. 

    Regards,

    Jack