PCB copy board
PCB copy board signal isolation technology is to enable digital or analog signal is sent when there is no crossing barrier between the sending and receiving end of the current connection . This allows the sending and receiving end of outside or in baseline level of difference can be as high as several thousand volts , and to prevent possible damage to the signal ground potential difference between the loop current , mainly used in : ( 1) systematically compare the noise Large , easy to damage the signal isolation.
PCB copy board signal isolation technology is to enable digital or analog signal is sent when there is no crossing barrier between the sending and receiving end of the current connection . This allows the sending and receiving end of outside or in baseline level of difference can be as high as several thousand volts , and to prevent possible damage to the signal ground potential difference between the loop current , mainly used in :
(1 ) systematic noise relatively large , easy to damage the signal , the signal can be separated to isolate a clean signal sub-system , the power supply to ensure the reliability of isolated part of the signal to achieve the system design requirements.
(2) The system voltage difference is very great. For example, in strong electric circuits , we often through isolation, the voltage conversion to the IC within the scope of work permitted .
(3 ) reference level electrical connection between the operator can generate an insecurity for the current path . By isolating the current control in a safe range.
In isolationtechnology , the designer was isolated according to the signal and the isolation requirements of different types to choose different isolation devices is the key :
(1 ) The first isolation device depends on the optical transmitter and receiver to cross the separation barrier . There are optocoupler ( Figure 4-18 ) and isolation transceiver IC. Light to cut off the system by the current , capacitance to avoid electrical interference on . Such devices are used for digital signals.
(2 ) analog transformer , through the transformer coupling of electromagnetic sense to send signals and receive signals ( Figure 4-19 ) . More difficult to produce transformers , precise control of parameters is difficult and often impossible made of IC, it is not very easy to use . However, the question forced linear analog signal isolation using transformers .
(3 ) In order to overcome the inconvenience of using the transformer , engineers used analog signal modulated carrier wave to cross the barrier . So come up with a capacitor circuit coupled across the barrier modulation signals . Role in the separation barrier on the high conversion rate as a single capacitance transient voltage signal barrier device , developed two- capacitor differential circuit in order to minimize the error . Now capacitive barrier has been applied in the digital and analog isolation device .