PEF2091 Siemens Semiconductor Group, PEF2091 Datasheet - Page 70

• Manufacturer Part Number: PEF2091
• Description: ICs for Communications(ISDN Echocancellation Circuit)
• Manufacturer: Siemens Semiconductor Group

Semiconductor Group
3.6
The IOM
symmetrical full-duplex communication link, containing user data, control/programming
and status channels. The structure used follows the 2B + 1D-channel structure of ISDN.
The ISDN user data rate of 144 kbit/s (B1 + B2 + D) is transmitted in both directions over
the interface.
The IOM
3.6.1
The IOM
Data is carried over Data Upstream (DU) and Data Downstream (DD) signals. The
downstream and upstream direction are always defined with respect to the exchange.
Downstream refers to information flow from the exchange to the subscriber and
upstream vice versa respectively. The IOM
drain data lines with external pull-up resistors. However, if operation is logically
point-to-point, tristate operation is possible as well. For IOM
"Setting Operating Modes", page 50.
The data is clocked by a Data Clock (DCL) that operates at twice the data rate.
Note 7:
Frames are delimited by an 8-kHz Frame Synchronization Clock (FSC). Incoming data
is sampled on every second falling edge of the DCL clock.
Figure 23
Note 8:
®
®
®
-2 interface is a generalization and enhancement of the IOM
-2 interface comprises two clock lines for synchronization and two data lines.
-2 interface is used to interconnect telecommunication ICs. It provides a
This is the default setting. If the microprocessor mode and the master mode
are being used, DCL frequency can be set to the bit data rate, see "Setting
IOM
default setting. Nevertheless, it applies to the bit clock mode as well if DCL
frequencies are adjusted.
A device with an IOM
or sometimes just ’Master Mode’ if the IOM
delivered by this device. It is said to be in the ’IOM
sometimes just ’Slave Mode’ if the IOM
IOM
IOM
IOM
®
®
®
-2 Bit Clock Mode", page 56 for details. This section will deal with the
-2 Interface
-2 Frame Structure
®
-2 Clocks and Data Lines
®
-2 interface is said to be in the ’IOM
70
®
-2 Interface Specification describes open
®
-2 Clocks are input to this device.
®
-2 clocks FSC and DCL are
®
Functional Description
-2 mode setting refer to
®
-2 Slave Mode’ or
®
®
-2 Master Mode’
-1 interface.
Data Sheet 01.99
PEB 2091
PEF 2091