PEB2085 SIEMENS [Siemens Semiconductor Group], PEB2085 Datasheet - Page 82

• Manufacturer Part Number: PEB2085
• Description: ISDN SubscribernAccess Controller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

2.5.2
For both receive and transmit direction, a 2:1 transformer is used to connect the ISAC-S
transceiver to the 4 wire S/T interface. The connections are shown in figure 44.
Figure 44
Connection of the Line Transformers and Power Supply to the ISAC
The full-bauded pseudo-ternary pulse shaping is achieved with the integrated transmitter
which is realized as a current limited voltage source. A voltage of 2.1 V is delivered between
SX1-SX2, which yields a current of 7.5 mA over 280 .
Semiconductor Group
The external transformer of ratio 2:1 is needed in both receive and transmit direction to provide
for isolation and transform voltage levels according to CCITT recommendations.
The equivalent circuits of the integrated receiver and transmitter are shown in figure 45.
10 µF
+ 5 V
GND
Analog Functions
V
V
V
DD
SSD
SSA
PEB 2085
SR2
SX2
SR1
SX1
2 : 1
2 : 1
Transmit
Receive
ITS02339
Pair
Pair
82
10 µF
+ 5 V
GND
V
V
V
DD
SSD
SSA
PEB 2086
Functional Description
SR2
SX2
SR1
SX1
®
-S
2 : 1
2 : 1
Transmit
Receive
ITS05640
Pair
Pair