Linear Tech Hot Swappable I2C Isolator Enables Simple Interfacing Between Busses with Isolated Grounds
Linear Technology introduced the LTC4310, a hot swappable I²C isolator that provides bidirectional communication between two I²C busses whose grounds are isolated from one another. According to the company, I²C isolation has traditionally been achieved using up to four optocouplers and special buffers, described as a costly, large and relatively complicated technique.
The LTC4310 is said to simplify 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 LTC4310 allows the four digital transmit and receive signals to be bridged by an Ethernet transformer to achieve communications across voltage differences of more than 1500VRMS or capacitors for lower voltage differentials.
The LTC4310 is suitable for many isolated applications including isolated I²C, SMBus and PMBus interfaces, isolated power supplies, positive-to-negative rail communications and Power over Ethernet. Aside from providing I²C isolation, the LTC4310’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 busses. 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 30ms. In addition, the LTC4310 is equipped with 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.
The LTC4310-1 is intended for use in 100kHz systems and the LTC4310-2 is designed for 400kHz systems. Both versions are specified over the commercial and industrial temperature ranges, and offered in10-lead MSOP and 3 x 3mm DFN packages. Pricing begins at $1.48 each in 1,000 piece quantities.