Linear Technology LTC4310 hot swappable I2C isolator

Linear Technology has introduced the LTC4310, a hot swappable I²C isolator that provides bidirectional communication between two I²C buses whose grounds are isolated from one another.

I²C isolation has traditionally been achieved using up to four optocouplers and special buffers. The device simplifies I2C isolation by encoding and expanding the SDA and SCL signals into four unidirectional channels, ready to be transmitted over the isolation barrier and then decodes and recombines them using a second LTC4310, all while maintaining I²C signal integrity.

The device allows the four digital transmit and receive signals to be bridged by an ethernet transformer to achieve communications across voltage differences of more than 1500 RMS or capacitors for lower voltage differentials.

The isolator is suitable for many applications including isolated I²C, SMBus and PMBus interfaces, isolated power supplies, positive-to-negative rail communications and power over ethernet. The device’s built-in rise time accelerators provide strong pull-up currents on SCL and SDA rising edges to meet I²C rise time specifications for heavily loaded buses. Hot swap control circuitry prevents data corruption when a card is inserted or removed from a live bus. A stuck bus disconnect and recovery feature attempts to free the card if the bus is stuck low for more than 30 ms.

Thermal shutdown protection, a ‘ready’ digital output pin to indicate device operation and an enable pin for enabling the device or setting the device in a very low shutdown current mode are included features.

The isolator is intended for use in 100 kHz systems and the LTC4310-2 is designed for 400 kHz systems. Both versions are specified over the commercial and industrial temperature ranges.