PEF2091 Siemens Semiconductor Group, PEF2091 Datasheet - Page 157

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

Deactivated (Full Reset)
In the "Deactivated" state the device may enter the low power consumption condition.
The power-down mode is entered if no monitor messages are active or pending. In
power-down the Receiver and parts of the interface are deactivated while functions
related to the IOM
No signal is sent on the U-interface, the differential outputs AOUT and BOUT are set to
0 V. The IEC-Q waits for a wake-up signal TN from the NT side or an activation request
(AR, ARX, AR0, UAR or ARL) from the LT side to start an activation procedure.
For the recognition of the wake-up signal TN the following procedure applies:
– TN detected for 4 periods –> transfer within the "Deactivated" state into power-up
– In power-up both differential outputs are set to 3.2 V
– TN detected for a total of 12 consecutive periods –> transition criterion TN fulfilled,
– TN detected for more than 4 but less than 12 periods –> return to power-down
The input sensitivity stated "Analog Characteristics", page 266, presents the minimum
level required to meet the TN transition criterion. The power-up condition may thus
already be entered at a lower level.
Note 43: Refer also to Note 42, page 153, for more information about device
EC Converged
Upon the EC-coefficients having converged, the IEC-Q starts the transmission of signal
SL2 and waits for the receipt of signal SN2 from the NT (SEC). If this condition is not met
within T6, the start-up procedure will be continued. In the case of an analog loop-back,
this state is left immediately because the EC compensates for the looped back transmit
signal.
EC-Training
The signal SL1 is transmitted on the U-interface to allow the LT Receiver to update its
EC-coefficients. The "EC-training" state is left when the EC has converged (LSEC) or
when timer T5 has elapsed. Timer T5 allows the start-up procedure to proceed even if
LSEC could not be detected, e.g. due to a high noise level on the U-interface.
EQ-Training
The "EQ-Training" is left after the Receiver has achieved synchronization and the
superframe indication has been detected (SFD). Upon expiry of timer T1 the C/I-channel
indication EI3 is issued.
Semiconductor Group
change to next state, if in addition the C/I-command DC is issued in the downstream
direction.
behavior when a wake-up tone TN is detected in the deactivated state.
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-2-interface and the wake-up detector are still active.
157
Operational Description
Data Sheet 01.99
PEB 2091
PEF 2091