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UTP / STP Links Using
Optocouplers as Isolators
Transmisii de date pe cabluri
UTP / STP cu separare prin
optocuploare
Basic Isolation Circuit
( switch-mode)
Exemplu de circuit de separare
Optocoupler Interface provides dual Light-Barrier
to protect the transmitter
BALUN :
BALUN = Balanced – Unbalanced Mode
Semi-duplex Link Uses Optocouplers
to Isolate Both Directions
Serial Interface Takes 4-Optocouplers
to Achieve Bi-directional Communication
Typically distorted rectangular wave shows reflections
Current Loop
Variations in line-impedance are rejected
Signal Formats
Simple :
Unbalanced termination of an UTP link
uses a voltage signal for transmission, and an
optocoupler to isolate the receiver from
the line
Overvoltage protection clamp
does not alter isolation and preserves tramsmission speed
Stronger Clamp
recommended for higher current UTP links
Differential UTP communication also allows
mutual protection of transmitting LEDs
Differential UTP-transmission
also providing bi-polar clamp
For most reliable transmission
Current-loop is recommended
Current-mode link termination can be easily made
bi-polar by using a Graetz-bridge