DS2148 Dallas Semiconducotr, DS2148 Datasheet - Page 53

• Manufacturer Part Number: DS2148
• Description: 5V E1/T1/J1 Line Interface
• Manufacturer: Dallas Semiconducotr

PROTECTED INTERFACE USING EXTERNAL RECEIVE TERMINATION
Figure 9-3
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
7) Rr = 37.5W for 75W, 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
9) The transmit transformer turns ratio (N) would be 1:1.36 for 5V operation.
10) The 68mF is used to keep the local power plane potential within tolerance during a surge.
Transmit
Receive
Line
Line
adjusted to match the line impedance.
for T1 applications.
Fuse
Fuse
Fuse
Fuse
(optional)
(optional)
Rp
Rp
toward the network)
Rp
Rp
(larger winding
N:1
1:1
0.1µF
Rr
S
Rt
Rt
Rr
polarized)
470
470
0.47µF
(non-
D3
D1
C1
+V
DD
53 of 75
D2
D4
TTIP
TRING
RTIP
RRING
DS2148
V
V
V
V
DD
DD
SS
SS
MCLK
(21)
(22)
(36)
(35)
0.01µF
0.1µF
0.1µF
2.048MHz
(this clock can also
be 1.544MHz for T1
only applications)
10µF
10µF
+V
DD
68µF