am79c30a Advanced Micro Devices, am79c30a Datasheet - Page 54

• Manufacturer Part Number: am79c30a
• Description: Digital Subscriber Controller ?dsc ?circuit
• Manufacturer: Advanced Micro Devices

Intelligent NT
Either Slave mode can be used to implement the Intel-
ligent NT configuration. The diagram below depicts this
configuration using DSC Slave mode with bus reversal
disabled.
The U-transceiver operates as the IOM-2 master de-
vice, programmed to TE mode and outputting at
1536-kHz DCL. The DSC indicates a D-channel re-
quest according to the TIC bus procedure using the
BAC bit on the DU line (BAC=0). The S-transceiver sur-
veys the received D channel and if it is idle, enables the
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DSC
D-channel
E-channel
S Interface
SBOUT
SBIN
Figure 11. IOM-2 Intelligent Configuration
B1, B2, D, MON0, C/I0,
IC1, IC2, MON1, C/I1, S/G(in), TIC(out)
S-transceiver
Am79C30A/32A Data Sheet
LT-S
DD
DU
DSC to send its D-channel frame to the U-transceiver
on DU by driving S/G low on DD. The S-transceiver
also sets its transmitted E-channel bits on the S-Inter-
face to zero (inversion of received D bits) to prevent all
connected TEs from transmitting data into the D-chan-
nel. When the DSC completes its D-channel transmis-
sion, it releases the TIC bus by setting BAC=1. The
S-transceiver then mirrors the incoming D bits into the
E-channel, thus behaving as a normal NT with trans-
parent D-channel handling.
DOUT/DD
U-transceiver
Master
downstream
upstream
DIN/DU