MC145650 Просмотр технического описания (PDF) - Motorola => Freescale
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MC145650 Datasheet PDF : 6 Pages
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FUNCTIONAL DESCRIPTION
All of the basic functions required to perform both the transmit and the receive operations in a category 2 ADSL modem are con-
tained within the MC145650. These functions include those that make up the transmit and receive data processing as well as
the control, timing and test functions that are outside the data path. A detailed functional block diagram of the MC145650 is
shown in Figure 1.
Digital
Ports
Interleaver
Memory
Port
Digital Interface
FEC
Multiplex Interleave TCM
DMT Processor
Analog Front
End
DMT
Modulator
Transmit
DAC Amplifier
Echo Canceller
Clip Mitigation
De-
multiplex
FEC
De-
Viterbi
interleave
DMT
Demodulator
ADC
Receive
Filter
TXA Port
External
Line
Interface
RXA Port
Host
Microprocessor
Interface
Host
Crystal
Oscillator/PLL
Timing
Test
Control
Test
Control Port
Clock Port
JTAG
Figure 1. MC145650 Block Diagram
Digital Interface
Input and output data is transferred through the MC145650
digital interface. The MC145650 can support up to seven
independent data streams, or bearer services, on its digital
ports. The digital ports include four simplex ports for transmit-
ting data downstream (as from an ADSL unit in a Central
office (CO) to an ADSL remote terminal or subscriber box),
and three duplex ports for bidirectional data transfers. All
three duplex ports may be reconfigured to provide upstream
simplex channels. The digital interface also provides framing,
deframing, trellis encoding/decoding, and data interleaving
functions.
Table 1. Supported Port Rates.
Port
A
B
C
D
E
F
G
Type
Simplex
Simplex
Simplex
Simplex
Duplex/Simplex
Duplex/Simplex
Duplex/Simplex
Min.
32 kbps
32 kbps
32 kbps
32 kbps
16 kbps
32 kbps
32 kbps
Max.
10.752 Mbps
4.608 Mbps
3.072 Mbps
2.048 Mbps
1.024 Mbps
1.024 Mbps
1.024 Mbps
Interleaver Memory Port
The interleaver memory port provides address, data, and
control lines for interfacing to a fast static RAM used for inter-
leave storage.
DMT Processor
The DMT processor consists of an embedded DSP and
peripherals that perform the modulation, demodulation, and
echo cancellation for the system. Both transmit and receive
data processing is handled by the DMT processor, via the
Analog Front End (AFE) and the digital interface.
Analog Front End (AFE)
The AFE performs the digital-to-analog conversions on the
data samples received from the DMT processor and then pro-
vides the necessary filtering and signal conditioning for trans-
mission on the line interface. During the receive operation,
the AFE filters the analog input and then performs the ana-
log-to-digital conversion, sending the digital samples on to
the DMT processor.
2
MC145650PP2/D
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