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TCA4307: Different Voltage on each side

Steven Richardson
Prodigy 30 points

Part Number: TCA4307

Hi, I was wondering if the TCA4307 can support voltage level translation through the buffer like the Analog LTC4304 as these parts are almost drop in replacements.

I would be interested in knowing if I can run the OUT side at 5V with pull ups to 5V and the VCC and IN side at 3.3V. 

We run the OUT side off-board over cable and use 5V. The LTC4304 is currently used as it allows voltage translation, protects against stuck buses and isolates the bus capacitance.

Thanks

  • 0
    Guru 321890 points

    Yes; the I/O pins are overvoltage tolerant.

  • 0 in reply to Clemens Ladisch
    TI__Guru 58958 points

    Hi Steven,

    As Clemens mentioned, the TCA4307 SDAIN/SCLIN/SDAOUT/SCLOUT pins are over-voltage tolerant. In the datasheet, the recommended operating conditions for these pins are bound from 0V to 5.5V not based off of the supply voltage VCC. If you operate at a VCC of 3.3V, input side = 3.3V, and output side = 5.0V, this should be okay. 

    When the device passes a high signal, I believe the buffer will drive to the 3.3V logic level before releasing the bus. Then the pull-up resistor on the 5V side will take over with an RC like edge. This shouldn't effect I2C transmission, but might make the data look a bit interesting on the o-scope.

    Regards,

    Tyler