8.1 Overview

The TCA4311A is a bidirectional I²C buffer optimized for hot-swap applications. The device supports I/O card insertion into a live backplane operating in Standard-Mode (100 kHz) or Fast-Mode (400 kHz). Initially, there is no connection between SCLIN and SCLOUT or between SDAIN and SDAOUT. Upon connection, the TCA4311A provides bidirectional buffering, keeping the card and backplane capacitances isolated from each other.

A pre-charge voltage on all SCL and SDA pins prevents the TCA4311A from disrupting I²C bus communication during insertion. Bus idle detection determines that there is no communication on the I²C line when the connection from –IN to –OUT is made. Once the connection is made, the READY pin will output a logic high signal. If the I²C bus will be inactive for extended periods of time, the TCA4311A can be put in shutdown mode by setting the EN pin to a logic low state. The TCA4311A resumes normal operation when EN is in a logic high state.

As with all I²C buffers, the TCA4311A requires pull-up resistors on all SCL and SDA pins due to the open-drain output circuitry. However, the integration of rise time accelerators allowed the use of weaker pull-up resistors than would normally be required.