1 Introduction

Electrical isolation is a means of preventing unwanted direct current (DC) and alternating current (AC) between two parts of a system while still enabling signal and power transfer between those two parts. Signal and power isolation is needed in a wide variety of applications for electrical safety, as well as for the protection of sensitive circuitry under fault conditions, to protect human operators and low-voltage circuitry from high voltages, to improve noise immunity, and to safely withstand ground potential differences between communicating circuits.

Optocouplers, also known as photocouplers, opto-isolators, and optical isolators, are recognized by most design engineers as a common design for achieving galvanic isolation for their system signals. Since optocouplers were one of the first isolators introduced in the semiconductor industry and have been around since the 1970’s, optocouplers have and continue to play a critical role in providing both basic and reinforced safety isolation for most industrial end equipment. While significant improvements have been made to optocoupler technology over the past 50 years, there seems to be a ceiling to their advancement in electrical characteristics, high-voltage reliability, and capability to integrate additional system functionality. This problem has left designers looking for alternative designs to keep up with the pace of their quickly evolving system needs. With semiconductor technological advances in the last couple decades, there are many other isolation technologies, such as capacitive and magnetic isolation, that offer similar functionality as optocouplers with better overall performance. Among the competing technologies is TI’s silicon dioxide (SiO₂)-based digital isolation technology. TI has been improving and investing in this technology since the early 2000’s. Before now, this technology has been used to design and grow a vast portfolio of digital isolator products. While digital isolators and optocouplers both provide isolation, (for example, to allow signal communication while blocking high-voltage and breaking ground loops) the two isolator types have plenty of differences that system design engineers must consider.