TCA4307 Hot-Swappable I2C Bus Buffer Texas Instruments TCA4307 Hot-Swappable I2C Bus Buffer supports I/O card insertion into a live backplane without the corruption of the data and clock lines. Control circuitry prevents the backplane-side I2C lines (in) from being connected to the card-side I2C lines (out) until a stop command or bus idle condition occurs on the backplane without bus contention on the card. When the connection is made, this device provides bidirectional buffering, keeping the backplane and card capacitances isolated. During insertion, the SDA and SCL lines are pre-charged to 1V to minimize the current required to charge the parasitic capacitance of the device.