USB isolated optocoupler products market, out of date? (1)

"Recently we were in Beijing made a reference platform, but in connection with the notebook, many interface speed is not enough," ADI Asia Pacific medical Enterprise senior business manager Paul is better than no feelings tell EEWORLD.

If you must isolate a PC connected devices, people naturally will select the USB interface.

Especially for the health of millions of people around the world to maintain, for patient care, disease management, sanitation and health, as well as drug distribution device is indispensable, therefore to support USB health care equipment demand growth.

Although, in the 1970s to develop optical Coupler, because of its signal one-way transmission, input and output fully implements the electrical isolation isolation, output signal on the input side effect free, strong anti-interference ability, stable, non-contact, long service life, transport efficiency higher benefits, in occupies not USB isolation's market share, however small, infinite design complexity increases, more IC demand and the cost associated with it, have influenced the design of the USB isolation.

Magnetic coupling PK optical coupling transformer, coupling capacitors, optical coupler and iCoupler isolator — provides current isolation of typical methods that can interrupt the current between two points, while allowing the data successfully passed.

The so-called "isolate" is used to protect the equipment against power surges, or ground loops caused by high voltage or current. Been long cable separation system ground because not in equal potentials, and current will flow between the two systems. If you do not use isolation, these current introduces noise, reduce the measurement quality, even the destruction of the system components.

Among them, the optical coupling is the application of a broad range of products, it is light as a medium to transmit signals to the input and output signals are good isolation effect, generally consists of three parts: the light emission, light reception and signal amplification.

Input signal driving light-emitting diode (LED) to issue certain wavelengths of light, light detector receive the photocurrent, after further amplified output. This completes the electro-optical-electrical conversion, so the input and output, isolating function. Since optical coupler input output isolated, signal transmission has been unilaterally, and other characteristics, and therefore has good electrical insulating capacity and a antijamming ability. And because of the optical coupler input terminal belongs to the current work of low resistance components, thus has a strong common-mode rejection.

However, precisely because of the electro-optical-electrical conversion has a certain ratio, but this rate increases with temperature.

At the same time, the LED itself also increases as the temperature and time shift, resulting in environmental comparison strict reliability should be improved.