TCA9511A Hot-Swappable I2C Bus and SMBus Buffer

Texas Instruments' TCA9511A hot-swappable I²C bus buffer supports I/O card insertion into a live backplane without corruption of the data and clock buses. 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 which keeps the backplane and card capacitances separated. During insertion, the SDA and SCL lines are pre-charged to 1 V which minimizes the current required to charge the parasitic capacitance of the device.

When the I²C-bus is idle, the TCA9511A can be put into shutdown-mode by setting the EN-pin low, reducing power consumption. When the EN is pulled high, the TCA9511A resumes normal operation. The open-drain READY output pin indicates that the backplane and card sides are connected. When READY is high, the SDAIN and SCLIN are connected to SDAOUT and SCLOUT. When the two sides are disconnected, READY is low.