PEF2091 Siemens Semiconductor Group, PEF2091 Datasheet - Page 149

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

DR
DT
LTD
Semiconductor Group
initiates an activation request. This can be done in the following manner
- Assumption: The IEC-Q on the LT side is in the "S/T Deactivated" state. It
receives SAI=0 from the NT side, i.e. the terminal is deactivated. The
control unit on the LT side issues the C/I command UAR. The IEC-Q on the
LT side issues the C/I indication UAI.
- The terminal initiates an activation requests, i.e. it issues the C/I command
"AR" on the NT side. This causes the IEC-Q on the NT side to transmit
SAI=1 on U.
- Upon detection of SAI=1 the IEC-Q on the LT side issues the C/I indication
AR.
- The control unit on the LT side can now issue the C/I command DC. This
causes the IEC-Q on the LT side to reflect the polarity of the SAI bit on the
UOA bit (see also "Signals on U-Interface", page 156). I.e., the IEC-Q on the
LT side transmits UOA=1 on U.
- Upon reception of UOA=1 the IEC-Q on the NT side transmits ACT=1 to U
if it is controlled as given in the NT state machine (see "NT Modes State
Diagram", page 161 ff.). Transparency can now be achieved in the usual
manner.
Deactivation Request
This command requests the IEC-Q to start a deactivation procedure by
setting the DEA bit to "0" and to cease transmission afterwards. The
DR-code is a conditional command causing the IEC-Q only to react in the
states "Test", "S/T Deactivated", "Line Active", "Pending Transparent" and
"Transparent", i.e. when the C/I-channel codes DEAC, UAI, AR, AI, FJ or
EI2 are issued on DOUT.
Data Through
This unconditional command is used for test purposes only and forces the
IEC-Q into the transparent state independent of the wake-up protocol. A
far-end transceiver needs not to be connected; in case a far-end transceiver
is present it is assumed to be in the same condition. Note however that the
C/I indication (initiated by the IEC-Q) in this case depends on the state of
the far-end transceiver and is not specified.
LT Disable
This is an unconditional command which requests the IEC-Q to switch-off
the remote-power-feed circuit for the subscriber line by activating the pin
DISS.
The IEC-Q is transferred to the "Test" state; the Receiver will not be reset.
149
Operational Description
Data Sheet 01.99
PEB 2091
PEF 2091