Application of PCB board signal isolation technology

PCB board signal isolation technology is to make analog or digital signals do not exist between the receiving end of the transmission and transmission through the transmission of the current connection. This allows the difference between the ground and reference level of the transmitter and receiver, up to several thousand volts, and prevents the damage of the loop current between the different potential voltages of the signal.

Mainly used in:

1 system noise, signal isolation technology can be easily damaged, splitting the signal into another clean signal subsystem, power supply, so as to ensure the reliability of isolated parts of the signal, and ultimately achieve the design requirements of the system.

2., the system voltage difference is too large, for example, in the high voltage circuit, we have to isolate the operating voltage can be converted to the allowable range of work within the IC.

An electrical connection between the 3. reference levels produces a current path that is not safe to the operator. By isolating the current, it can be controlled in a safe range.

In isolation technology, the designer chooses the different isolation devices according to the isolated signal types and isolation requirements:

1 first class isolation devices depend on the receiver and the optical transmitter to break the isolation barrier, mainly IC transceivers and optical coupler, with light barrier system current, capacitance can avoid interference on the electrical, such devices are suitable for digital signal.

2. the analog transformer transmits and receives signals through the electromagnetic sense of the transformer. Because the transformer is difficult to manufacture, and can not accurately control its parameters, and usually can not be made into IC, so it is very inconvenient to use, but the problem of linearization forced the analog signal isolation to use the transformer.

3 in order to solve the transformer is not convenient to use, the engineers used a modulated carrier analog signal to break through the barrier, to come up with the coupling capacitor circuit with modulation signal in order to break through the barrier, high conversion function in isolation barrier on the rate of transient voltage as signal single capacitor barrier devices, developed a double differential capacitance the circuit, thus the error is reduced to a minimum, now capacitive barrier technology has been widely used in digital and analog devices in isolation.