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PCA9306: PCA9306 Schematic Confiramation

Shenhua Zhang
Prodigy 640 points
Part Number: PCA9306

Hi TRX expert,

My cusotmers are using PCA9306 for +3.3v_STBY to 1.8v I2C bus lever translator, and +3.3v_STBY I2C device is master, 1.8v I2C device is slave.

+3.3v_STBY is standby power, 1.8v is main power, which means +3.3v_STBY is always on, 1.8v is only on when blade host power on.

So please help check if MEZZ_I2CA_SCL/SDA I2C master bus is tied to GND or other undetermined state when 1.8v is off. Because there are other I2C devices connected to MEZZ_I2CA_SCL/SDA I2C master bus with standby power.

 

  • 0
    TI__Guru 53555 points

    Hi Shenhua,

    I do not recommend allowing the device to remain in a state where Vref1 is unpowered (floating) while Vref2 and EN are active. In this state there will be a leakage current from Vref2 to Vref1. Depending on the state of the disabled supply line, this could also disrupt I2C communication on the side-2 of the device. 

    If possible, I would advise using PCA9306 EN pin (with 3.3V) to disable the device when the 1.8V supply will not be active. This will put the device in a high-z state stopping Verf2 to Vref1 leakage and allowing communication to continue on side-2. 

    Let me know if this solution is not possible or if you would like other suggestions.

    Regards,
    Eric