DS21348

Manufacturer Part NumberDS21348
Description3.3V E1/T1/J1 Line Interface
ManufacturerDallas Semiconducotr
DS21348 datasheet
 


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PROTECTED INTERFACE USING EXTERNAL RECEIVE TERMINATION
Figure 9-3
(optional)
Rp
Fuse
Transmit
Line
Fuse
Rp
(larger winding
toward the network)
Rp
Fuse
Receive
Line
Fuse
Rp
(optional)
NOTES:
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.
+VDD
D1
D2
Rt
1.0µF
S
(non-
C1
polarized)
Rt
D3
D4
N:1
470
470
1:1
Rr
Rr
0.1µF
51 of 73
DS21348
0.1µF
TTIP
VDD (21)
VSS (22)
10µF
0.01µF
TRING
VDD (36)
0.1µF
VSS (35)
10µF
MCLK
2.048MHz
RTIP
(this clock can also
be 1.544MHz for T1
RRING
only applications)
+VDD
68µF