Field of the Invention
The invention relates to isolation technology and more particularly to communication across an isolation channel.
Description of the Related Art
In a typical control application, a processor system provides one or more control signals for controlling a load system. During normal operation, a large DC or transient voltage difference may exist between the power domain of the processor system and the power domain of the load system, thus requiring an isolation barrier between the processor system and the load system. For example, one domain may be “grounded” at a voltage that is switching with respect to earth ground by hundreds or thousands of volts. Even when the expected voltage difference between the domains is small in normal operation, isolation increases safety in some applications. For example, in a biomedical application that includes electrodes taped to a patient's body, even if a measurement device is properly grounded, isolation increases protection of the patient.
Accordingly, an intermediate system includes isolation that prevents damaging currents from flowing between the processor system and the load system. Although the isolation prevents the processor system from being coupled to the load by a direct conduction path, an isolation channel allows communication between the two systems using optical (opto-isolators), capacitive, inductive (transformers), or electromagnetic techniques. However, such communication is susceptible to common mode transients that can interfere with the accuracy of the information transmitted across the isolation channel. Thus, isolation technology with immunity to common mode transients is desirable.