ACS406CS Semtech Corporation, ACS406CS Datasheet - Page 6

• Manufacturer Part Number: ACS406CS
• Description: Two-chip Fiber Optic Modem Ics / ACS4060 100-pin Tqfp, ACS9010 44-pin TQFP
• Manufacturer: Semtech Corporation

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
33.792MHz, this gives a maximum bandwidth of
8.448MHz (E2). This bandwidth can be utilised in
various ways, it may be divided up over 1,2,4 or 8
channels. It is also possible to support 1,2 or 4
independent clocks. Single clock operation is known
as TX1 mode and dual clock as TX2 and four
independent clocks is known as TX4 mode. There is
a fourth mode of operation known as HT mode (High
Tolerance), which is more fully described later. For
the purpose of this specification these transmission
modes are known collectively as the Tmodes.
The data rate selection pins DR(5:1) determine the
frequency of the TCLK clock, the number of channels
and the transmission mode (TMode) in accordance
with the Table 3.
It is possible to configure the DR pins setting on
each side of the link differently (with input Fhold) as
long as identical crystal values are observed on the
communicating devices. For example, the near-end
Data Rate Selection
Asymmetrical Data Rates
5 4 3 2 1
1 1 1 1 1
1 1 1 1 0
1 1 1 0 1
1 1 1 0 0
1 1 0 1 1
1 1 0 1 0
1 1 0 0 1
1 1 0 0 0
1 0 1 1 1
1 0 1 1 0
1 0 1 0 1
1 0 1 0 0
1 0 0 1 1
1 0 0 1 0
1 0 0 0 1
1 0 0 0 0
0 1 1 1 1
0 1 1 1 0
* 50 Km modes
DR Pins
TCLK
freq
XTAL/4
XTAL/5
XTAL/16
XTAL/20
XTAL/16
XTAL/20
XTAL/16
XTAL/20
XTAL/32
XTAL/64
XTAL/32
XTAL/64
XTAL/128
XTAL/256
XTAL/8
XTAL/10
XTAL/16
XTAL/20
Nos. of
channels
2
2
1
1
4
4
4
4
8
8
4
4
1
1
8
8
1
1
Tmode
Tx1
Tx1
Tx2
Tx2
HT
HT
Tx1
Tx1
Tx2
Tx2
Tx1
Tx2
Tx2
Tx2
Tx1*
Tx1*
Tx4
Tx4
Table 3
6
ACS406CS may be configured to transmit 8 channels
at 1Mbps and the far-end modem may be configured
to transmit 1 channel at 8Mbps. For asymmetrical
communication, set fhold = 0, this will lead to the
receive circuitry reading the DR pins settings from
the far-end ACS406CS rather than locally. It is
important that the receive circuitry is aware of the
configuration and formatting of the data so that it
can correctly interpret it. Prior to lock (when DCD =
0), the receive circuitry will default to the local DR
pin settings.
For symmetrical communication (with input Fhold =
1), DR pins setting sent over the link are ignored
and the receive circuitry will always read the locally
set DR pin values.
It is expected that for the vast majority of applications
symmetrical communication will be employed. When
asymmetrical mode is selected (Fhold = 0), the only
valid DM settings are the Full Duplex modes. The
other modes of Remote-Loop-back, Local-Loop-back,
master and slave (as described in the sections
headed Configuration modes & Diagnostic modes)
are not available.
There are four choices for multi-channel operation
on the ACS406CS, selected by the DR(5:1) pins,
namely, 1, 2, 4 or 8 channel operation.
RNEG1 is the only active channel. Data appearing on
other TPN inputs is ignored. All other RPN outputs are
forced to the zero state.
In 2-channel operation channel mappings can be
seen in Table 4. Data appearing on all other TPN
inputs is ignored. All other RPN outputs are forced
to the zero state.
In 4-channel operation the mappings can be seen in
Table 5.
In 1-channel operation TPOS1/TNEG1 and RPOS1/
Multi-Channel Operation
1-Channel Operation
2-Channel Operation
4-Channel Operation
Channel Nos.
1
2
TPOS1/TNEG1
TPOS2/TNEG2
Input
ACS406CS Issue 1.6 January 1999.
Table 4
RPOS1/RNEG1
RPOS2/RNEG2
Output