1 What is Isolated I²C?

I2C helps controllers communicate with sensors, data converters, and other nearby integrated circuits (ICs). Isolated I2C-compatible signal isolators like TI’s ISO1640 and ISO1641 create opportunities for the protocol to be used in systems that are physically distant, operating at different local voltage potentials, and require isolation protection for operation or safety.

Sensitive systems or those in need of protection from large DC and AC currents, ground-potential differences, and high-voltage events can be protected by TI’s digital isolators when used with isolated power supplies. Although most digital isolation devices isolate signals in one direction for communication across an isolation barrier, TI’s bidirectional signal isolators isolate bidirectional signals for I2C. They accomplish this by combining two unidirectional signal paths internally, as Figure 1-1 shows, across the industry’s strongest silicon dioxide (SiO2) isolation barrier.

Figure 1-1 Simplified Schematic of a Bidirectional I2C Isolation Channel

Bidirectional communication is inherent to I2C, and using an isolator with integrated bidirectional lines provides the benefits of: a low discrete component count, small footprint, less system-wide variations, and built-in protection over discrete solutions.