PEB2080 SIEMENS [Siemens Semiconductor Group], PEB2080 Datasheet - Page 26

• Manufacturer Part Number: PEB2080
• Description: S/T Bus Interface Circuit(SBC)
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

Functional Description
2.4
Individual Functions
The SBC transmits data between the IOM interface and the line interface. The relative frame
positions have been selected to minimize the round trip delays of the B channels, which are:
125 s for TE, NT and LT-S in normal IOM mode, max. 250 s for LT-T in normal IOM mode and
LT-S in inverted mux mode and, finally, max. 375 s for LT-T in inverted mux mode.
In the active state the data of the B channels are switched through transparently. The same applies
to the D channel, except in TE mode where D-channel switching is subject to the S bus D-channel
access procedure and collision detection.
S/T Interface Pre-Filter
In some applications it may be desirable to improve the signal-to-noise ratio of the received S/T
interface signal by filtering out undesirable frequency (usually high frequency) components. This
may be realized by an external pre-filter.
To simplify the implementation of this filter, an operational amplifier is integrated in the ISAC-S, as
shown in figure 13. By connecting an RC network between input SR2 and the extra pin UFI an
active RC filter of desired order can be realized (one example is shown in figure 13b).
Figure 13a
Prefilter Connections
Semiconductor Group
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