PROTECTED INTERFACE USING EXTERNAL RECEIVE TERMINATION
toward the network)
1. All resistor values are ±1%.
2. C1 = 0.1µF.
3. S is a 6V transient suppresser.
4. D1 to D4 are Schottky diodes.
5. The fuses are optional to prevent AC power line crosses from compromising the transformers.
6. Rp resistors exist to keep the Fuses from opening during a surge. If they are used, then Rr must be
adjusted to match the line impedance.
7. Rr = 37.5W for 75W or 60W for 120W E1 systems, or 50W for 100W T1 lines.
8. The Rt resistors are used to increase the transmitter return loss (Table 9-1). No return loss is required
for T1 applications.
9. The transmit transformer turns ratio (N) would be 1:2 for 3.3V operation.
10. The 68mF is used to keep the local power plane potential within tolerance during a surge.
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(this clock can also
be 1.544MHz for T1