ACS411CS Semtech Corporation, ACS411CS Datasheet - Page 7

• Manufacturer Part Number: ACS411CS
• Description: Acapella Optical Modem ic
• Manufacturer: Semtech Corporation

The crystal clock frequency and the multiplying factors
of the MPLL are determined by the choice of data
rates. Table 2 lists the required frequencies of the
system.
The main synchronous channels may use any of the
following coding methods: NRZ, AMI, HDB3, B3ZS,
B6ZS and B8ZS. The desired mode is selected by
POL(3:1) input pins, as shown in Table 3.
For Non-Return-to-Zero (NRZ) coding, data is applied
directly to TPOS inputs, and output data appears
only on the RPOS output pins . When using NRZ
code, unconnected TNEG input pins will automatically
pull-up to VD+. In addition, the ACS411CS will assert
a continuous Low on redundant RNEG output pins.
AMI, B3ZS, B6ZS, B8ZS and HDB3 coding is
normally bipolar. However, it is possible to interface
with the ACS411CS using two inputs and outputs
rather than a single bipolar interface. Data equivalent
to positive excursions of the bipolar AMI/BxZS/HDB3
signal are applied as a logic High to TPOS, while
data equivalent to negative excursions are applied
as a logic High to TNEG. Similarly, AMI/BxZS/HDB3
positive excursions will appear as a logic High on
RPOS and negative excursions will appear as a logic
High on RNEG.
System Frequencies and Clock Generation
Data Coding
16 x T1
16 x E1
7 x T2
4 x E2
1 x E3
1 x T3
1 x OC1
Mode
Data
Coding
NRZ
AMI
HDB3
B8ZS
B6ZS
B3ZS
NRZ
NRZ
Table 3: Line coding selection
Table 2: System frequencies
Data Rate
1.544
2.048
6.312
8.448
44.736
51.840
34.368
MHz
POL3
0
0
0
0
1
1
1
1
23.160
22.528
23.144
22.528
22.912
22.368
25.920
XTAL
MHz
POL2
1
0
0
0
0
1
1
1
69.480
67.584
69.432
68.736
67.104
77.760
67.584
MHz
Fsys
POL1
0
1
0
1
0
1
0
1
7
It is anticipated that most users of the ACS411CS
will interface directly with a E1/T1 framers. All the
popular framers provide POS/NEG bipolar interfaces
which will directly connect to the ACS4110.
If required, a detailed description of the AMI/HDB3/
BxZS coding rules are available from Acapella.
For the purpose of this specification TPN1 represents
the set of signals TPOS1 and TNEG1, and RPN1
represents the set of signals RPOS1 and RNEG1.
See section headed, Data Coding for a description
of the coding types.
The maximum recommended crystal (XTAL) is
26.88MHz. An internal multiplier factors the XTAL
frequency by 3.
51.840MHz (OC1). This bandwidth can be utilised
in various ways, it may be divided up over 1, 4, 7 or
16 channels.
All 16 main channels are completely independent. One
channel consists of the following 6 signals:
Transmit side:
TPOS
TNEG
TCLK
Receive side:
RPOS
RNEG
RCLK
The data rate can be selected via the data rate selection
bits DR(4:1), either directly via pins or via the
microprocessor interface. The selection determines
the number of active channels in combination with the
selected crystal frequency and the line data rate in
accordance with Table 4.
Channels not used in a specific mode are disabled. For
example in 4 x E2 mode channels 1 to 4 are carrying
E2 data rates, and channels 5 to 16 are disabled. All
channels can be disabled individually via the
microprocessor interface, or alternatively via far-end
remote control.
Data Rate Selection
DR Pins
3
1
1
1
0
0
0
0
2
1
0
0
1
1
0
0
1
0
1
0
1
0
1
0
Table 4: Data rate and channel selection
+ve in bipolar signal or NRZ data
transmit clock (internal or external)
+ve in bipolar signal or NRZ data
receive clock
-ve in bipolar signal TPOS
-ve in bipolar signal or NRZ data
34.368
44.736
51.840
1.544
2.048
6.312
8.448
The maximum bandwidth is
TCLK
(MHz)
ACS411CS PRE-RELEASE Issue 6.0 July 1999.
16
16
7
4
1
1
1
Nos. of
channels
Tmode
16 x T1
16 x E1
7 x T2
4 x E2
1 x E3
1 x T3
1 x OC1