PEB 2091
PEF 2091
Application Hints
Note 74: These Parameter shall apply to the complete temperature range and life time.
The temperature range depends on the version used. For PEB 2091 it is
between 0°C and 70°C, for the PEF 2091 it is between -40°C and 85°C.
External Oscillator
Frequency:
Frequency tolerance:
15.36 MHz
80 ppm
In this case the requirements for the master clock are the same as the requirements in
the LT case. See "Master Clock", page 281 for details.
®
7.2
Applications with EPIC on the Line Card (PBX)
This section gives an example for using the S/G bit and BAC bit control feature (see
section 3.9, page 90) for D-channel arbitration in PBX applications with the PEB 20550
(ELIC®) used in the Line card.
The S/G bit on DOUT (downstream) and the BAC bit on DIN (upstream) can be used to
allow D-channel arbitration similar to the operation of the Upn interface realized with the
OCTAT-P and the ISAC®-P TE. The basic function is as follows:
The PBX line card using the ELIC® assigns one HDLC controller to a number of
terminals. As soon as one terminal T requests the D-channel, e.g. for signalization, all
other terminals receive a message indicating the D-channel to be blocked for them. The
request is done with the BAC bit. At terminal T the BAC bit is set and the IEC-Q transfers
the need for the D-channel to the LT side. There, the HDLC-controller is assigned to the
appropriate IOM®-2-channel. Once this is done and indicated to the terminal by means
of the S/G bit, the terminal begins to send D-channel messages.
Note that this procedure is somewhat different from the operation of the OCTAT-P used
with the ISAC®-P TE. There, the begin of the upstream D-channel data transfer itself
indicates the need for the HDLC-controller. This implies that any other terminal, that
incidentally sent a HDLC-message the same time, can be stopped before the message
is lost in case the HDLC-controller is not available. The U-interface featured by the
IEC-Q is not able to transfer the available/blocked information often enough to ensure
this. Hence, it is necessary to indicate a D-channel access by the terminal in advance.
"In advance" actually means about 14 ms.
Giving MON-0 25 at the LT during Transparent operation will cause the D-channel
H
access at the NT side to be on "STOP". As one EOC-message is transmitted via the
EOC-channel once every 6 ms, the S/G bit on IOM®-2 can be set in 6 ms intervals.
If the 4 channel PEB 24911 (DFE-Q) is used in the LT, a PEB 20550 (ELIC®) can
arbitrate the D-channel via the C/I command as known from the OCTAT-P and QUAT-S
devices. Please refer to the PEB 24911 Data Sheet for detailed information on this.
Semiconductor Group
253
Data Sheet 01.99
INFINEON [ Infineon ]
