The ToPSync™ ACS9550T ASSP utilizes Semtech's ToPSync™
technology which, in conjunction with an appropriate Precision
Time Protocol (PTP) Grandmaster, can be used for many
applications which require a reference frequency that is
traceable to a remote, centralized, frequency source, or a time
or phase reference that is aligned to a central reference point
of phase or time.
Whilst the distribution of a common frequency reference has
been a key technology in most telecom networks since the
beginning of digital networks, the techniques used do not work
on packet switched networks. A new technique is required,
and the ACS9550T has been developed using a combination
of PTP and adaptive packet delay filtering. Although PTP was
conceived to use on-path support such as boundary clocks or
transparent clocks, the packet delay filtering of the ACS9550T
renders such support unnecessary.
As an example, if WiBro/WiMax transmitter stations do not
have a common phase across the regions in which they
overlap, interslot interference can occur. For this application, it
is not enough to distribute a frequency reference since the
individual path delays to each transmitter would result in
individual phases with consequent interference. A sensible
solution to this problem is to use a two-way timing protocol
such as PTP to cancel out the path delay and provide a
common phase at each transmitter. This can be achieved even
on legacy packet networks that have no on-path support,
making it possible to time wireless transmitters over existing
packet networks.
For occasions when the timing packet stream fails, the
ACS9550T includes a holdover mode to maintain timing within
defined limits until the stream can be re-established.
ACS9550TPB_US, Revision 04, February 2010
©2010 Semtech Corp.
ADVANCED COMMS & SENSING
About the ToPSync™ ACS9550T
System diagram
Page 1
*
Features
Fully integrated - IEEE1588 (PTP) Slave function providing
reference frequency output. Time-of-Day (ToD) output and
one pulse per second (PPS) output. Powerful integrated
processor running clock recovery algorithm (a combination
of PTP and adaptive packet delay filtering).
PTP Grandmaster selection - configured or automatic
(according to the PTP Best Master Clock algorithm).
Multiple Grandmasters supported.
Powerful network delay analysis delivers full time
alignment in the slave over hostile networks (including
Layer 2 & 3 routed).
Dynamic adaptation to delay variations. Tolerant to network
loading changes (ramps and steps), routing changes and
temporary outages.
Operational support - unicast and multicast operation.
Configurable DiffServ codepoint - for high priority packet
routing.
Precision holdover.
Interfaces for:
Supports operation with a local oscillator accurate to
±20 ppm or better.
Time alignment performance better than ±1 s on a
managed 5-switch GbE network under G.8261
conditions.*
Frequency alignment performance better than ±10 ppb on
a managed 5-switch GbE network under G.8261
conditions.*
Standard compliance - IEEE 1588 v2
BGA package - 360 pin, 20 mm x 20 mm, 1 mm pitch.
Lead-free version available - RoHS
This is an indication of Semtech tested performance and is not
guaranteed across all types of switches and network conditions. Please
contact Semtech ToPSync
Time-aligned output pair:
1 PPS and 125 MHz divided by n (n = 4 to 125000).
Six frequency-aligned outputs:
1 Hz and programmable frequency 1 kHz to 62.5 MHz.
Media Independent Interface (Ethernet port).
Serial peripheral interface (SPI).
Local oscillator (reference frequency for internal clock
frequency).
SRAM port.
JTAG boundary scan port.
Timing-over-packet synchronization
TM
support for further details.
FINAL PRODUCT BRIEF
5
and WEEE
ToPSync™
1
, G.8261
www.semtech.com
ACS9550T
6
4
4
.
compliant.
test
4
test