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Bus Couplers
Bus Couplers

Bus Couplers

Bus couplers are used to connect any device to a bus protocol, they have single or multiple stub connections and each stub has a transformer inside to provide isolation and fault tolerance. DEICO has a wide range of cost-effective box couplers, inline couplers and PCB-type couplers from single stub to eight stubs with termination resistors optional for each side of the bus. DEICO also has the ability to design and manufacture any type of bus coupler according to customer requirements.

Bus coupler comes equipped with fault isolation resistors and a step-up transformer to avoid shorts, improve common mode rejection, and provide lightning immunity for the terminals connected to the bus. Direct coupling is also possible but not recommended for most cases. Below are some characteristic values for the bus:

  • Transmission line impedance is between 70-85 Ω (generally 78 Ω)
  • Fault isolation resistors are equal to 75% x Zo. (Zo is transmission line impedance)
  • Transformer ratio is 1:1.41
  • The power rate of resistors are at least 2W.
  • Transformer has a common mode rejection ratio greater than 45.0 dB at 1 MHz.
  • Voltage drop is maximum 20% at 250 kHz.
  • Overshot and ringing are ±1.0 V peak at 250 kHz.
  • Operating frequency range is between 75 kHz – 1.0 MHz.
  • Stub voltage is between 1.0 V to 14.0 V P-P, line to line.
  • The longest transformer coupled stub length is 20 feet.
  • The longest direct coupled stub length is 1 feet.