![]() ![]() It helped that worldwide green initiatives for a cleaner environment also mandated higher efficiency to reduce wasted energy. For this market, the most critical parameter was power density, and the mantra was W/mm 3. These power supplies were primarily used for servers and telecom base stations. The early adopters of digital technology were isolated power supply manufacturers. Other heavy-use applications include isolated power supplies used in telecom base stations and in servers that power the infrastructure behind our increasingly connected world – the Internet of Things. Industrial automation is the largest market for isolators, and designers of industrial systems value the high-temperature operation, superior part-to-part matching, low skew, and high noise immunity that CMOS isolators bring to the table. The most common applications for isolation are in the industrial market – in equipment such as factory automation, process control, programmable logic controllers (PLC) or process automation controllers (PAC), inverters for motor control and uninterruptable power supplies (UPS). In an increasingly bandwidth- and power-hungry world, new CMOS-based digital isolators provide an ideal solution. Industry trends and CMOS digital isolators Therefore, optos are only capable of lower data rates with large propagation delays and skew. Since optos basically function by switching the PN junction diode, they have a relatively slow switching rate. Digital isolators have no such physical limitations. ![]() Of course, these actions put limitations on the use case, since isolators are most useful in systems where such conditions exist intrinsically. Decrease operating diode current and ambient temperature.The designer can compensate for aging by doing several things: This had implications for the optocoupler’s long-term stability and operation, especially at high temperature operation. This is largely due to the electrical and thermal stressing of the PN junction. The quantum efficiency of the LED, defined as the total photons per electron of input current, decreases with time at a constant current. Figure 1 highlights the technology differences between optocouplers and digital isolators.įigure 1 Basic operation of opto vs capacitive coupled CMOS isolatorįigure 2 shows examples of X-ray images of an opto and a digital isolator to help visualize the physical construction of these devices.įigure 2 X-ray images of an optocoupler assembly (left) and a digital isolator assembly (right)Ī prominent characteristic of the opto is the aging problem. Optos were basically the only solution available until CMOS-based digital isolators were developed in the late 1990s using inductive (magnetic) or capacitive coupling to transfer the signal. They were all basically some sort of light-emitting structure (the miniature bulbs were replaced by a semiconductor-based light emitting diode or LED) on the primary side, coupled with various forms of light-sensitive devices, such as a photo-resistor, photo-transistor, photo-diode, or triac, that made the device suitable for a range of dc and ac applications.
0 Comments
Leave a Reply. |