ACS411CS Semtech Corporation, ACS411CS Datasheet - Page 23
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ACS411CS
Manufacturer Part Number
ACS411CS
Description
Acapella Optical Modem ic
Manufacturer
Semtech Corporation
Datasheet
1.ACS411CS.pdf
(43 pages)
Since LEDs or Lasers from different suppliers may
emit different wavelengths, it is recommended that
the Lasers/LEDs in a communicating pair of modems
are obtained from the same supplier. Acapella will
assist with contact names and addresses on request.
The ACS9020 contains a highly sensitive amplifier,
capable of responding to extremely low current levels.
To exploit this sensitivity it is important to reduce
external noise to a low level compared to the input
signal from the Laser/LED. The modem should have
an independent power trace to the point where power
enters the board.
The Laser/LED should be sited very close to the
PMN, PINP, PINN, LAN and LAP pins. A generous
ground plane should be provided, especially
surrounding the sensitive PINP and PINN tracks from
the ACS9020 pins to the optical component. The
modem should be protected from EMI/RFI sources
in the standard ways.
Laser/LED Considerations
Power Supply Decoupling
GND pins are
84, 108, 122, 123, 124, 128,
130, 138, 159, 160
VD+ pins are
82, 85, 94, 105, 139, 161,
162
VD+
5, 37, 51, 81,
ACS4110
6, 38, 52,
Figure 13: Power supply considerations.
VA+
100nF
23
There are two conditions that will make LOSS go to
Logic 1. These are:
i) Loss of synchronisation - synchronisation windows
incorrectly aligned i.e DCD=0.
ii) 64 received symbols break the 8B10B encoding
rules in a sequence of 256 symbols.
In order to return LOSS to the Logic 0 state the
following criteria must be met:
i)
synchronisation windows correctly aligned i.e DCD=1.
ii) There are no received symbols in a sequence of
256 symbols which break the 8B10B coding rules.
LOSS ( Loss Of Synchronisation)
The
devices
TXVDD
ACS9020
must
GND pins are
(2 off)
ACS411CS PRE-RELEASE Issue 6.0 July 1999.
be
synchronised
9, 24, 42, 58
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