MTC-20172-PC AMI Semiconductor, Inc., MTC-20172-PC Datasheet - Page 60

• Manufacturer Part Number: MTC-20172-PC
• Description: S Interface Circuit for ISDN (SIC)
• Manufacturer: AMI Semiconductor, Inc.

Remark 6 : The reaction of MTC-
20172 SIC on the AR command is not
required. However, the MTC-20172
SIC reacts on AR in state (1) as
indicated.
Remark 7 : If an accidental signal
on the S-bus (spike, EMC, ...) awakens
the MTC-20172 SIC, which goes to
state (4), the only way to return to
idle, state (3), is via the normal
activation and deactivation procedure.
Remark 8 : In the state (9), the
extended mode always answers with
RSYu; the basic mode can also signal
LSL and AIu, depending of the
receiver state. However, the MTC-
20172 SIC suppresses the LSL and
AIu indication during state (9).
Remark 9 : The command TM2 (test-
mode 2) exists only for the extended
mode. It could be considered illegal
for the basic mode and result in NO-
Operation. However, the implementa-
tion extends the TM2 command to the
basic mode.
Remark 10 : The "ei" indication,
i.e. both RSTB and SCZ- pin active, is
valid for the extended mode. The indi-
cation during active RSTB pin is TIM.
Remark 11: In state (9), the MTC-
20172 SIC sends INFO2 for ALL NT
modes. This is the most logical respon-
se. It keeps the S-bus active and
synchronous, with the B and D-chan-
nels downlink idle at all zero. Uplink
the B-channels are transparent, but the
D-channel will be idle, because the E-
channel downlink is forced to all zero.
Note that the multiframing S/Q-
channel will work also during INFO2!.
Remark 12 : In the loop modes
under command of ARL and AIL the
receiver sees the INFO2/4 of its own
transmitter as uplink signal instead of
actual INFO3. It ignores activity detec-
tion on the real S-bus. This bus will
activate normally, because the loop is
a transparent loop 2. The TEs could
even try to send LAPD messages, but
they are not terminated correctly.
6.5.3 State Diagram for the LT-S
Position
The state diagram of the LT-S is a
sparse version of the NT. The same
numbers and names are used. The
Figure of the state diagram is
organized with identical states on the
same position, with deletion of missing
states. The states (4), (6) and (9) do
not exist in the LT-S case.
State Names and Numbers
(1) G4 Pending Deactivation
This state is reached by the the uncon-
ditional "DR" deactivation request
command. After a timeout of 32 ms,
Fig. 6.9 : Desactivation Sequence
50
GCI
MTC-20172
Data Sheet & Reference Manual
Rev. 1.1 February 1997
or 16 ms of INFO0 reception, the
MTC-20172 SIC goes to state (2).
(2) G4 Unacknowledged
The MTC-20172 SIC is ready to
deactivate, signals "DIu", and waits
for the acknowledgement with
"did"="DC", and prepares the
internal idle state (see 6.2.4).
However, the GCI bus will not go to
idle.
(3) G1 Deactivated
The MTC-20172 SIC is not
transmitting. No signal is detected, no
activation is requested. This state is
closely linked with the state 12, which
is only defined for the extended mode.
(5) G2 Pending Activation
There are two ways to arrive in this
state:
GCI