ADVANCED COMMS & SENSING FINAL PRODUCT BRIEF
ACS9510PB_US, Revision 02, October 2008
©2008 Semtech Corp.
ACS9510 ToPSync™
www.semtech.com
Page 2
Hardware v 1.0
The ACS9510 is a multi-role device with multiple operating
modes. All modes support a large number of output clocks
that are locked to the selected timebase:
TDM Timed mode - in which the timebase is derived from
clocks, or recovered clocks, such as SONET, SDH, PDH,
SyncE, BITS, SSU, etc. This mode supports PTP
Grandmaster functions that transport the timing to a
remote node. The ToD output from a PTP Slave is ToPSync™
time, not UTC or TAI time.
PTP Network Timed mode - where the timebase is obtained
from a packet network and the ACS9510 operates as a PTP
Slave. In the PTP Network Timed mode, the device cannot
support PTP Grandmaster functions because the PTP is in
a slave state.
Reference Timed mode - in which timing derives from a
local source such as a local oscillator, GPS, or another
point of accurate frequency and/or time. This mode
supports PTP Grandmaster functions to transport the
timing to a remote node. If the reference input contains
UTC or TAI (such as GPS), then the PTP Slave output is UTC
or TAI. If ToD information is not available at the master,
then the PTP Slave delivers ToPSync™ time.
Self Test - in which the device self-checks for consistency,
tests the external SRAM for faults, and performs
rudimentary checks of the external Ethernet PHYs.
In all modes, a highly accurate timebase holdover operates if
the selected reference fails. Also the ACS9510 implements
selectable automatic switching between modes - for example,
hitless switching between clock references in TDM Timed
mode, and automatic switchover to PTP Network Timed mode
if all available clocks fail.
The ACS9510 provides timing solutions that deliver a
performance better than that required by the G.8133/G.8234/
G.8245/G.8261§/82626 standards. As a PTP Slave, the device
can align its timebase with that of the PTP Grandmaster and
generate time-of-day signals as well as clock signals. In this
state, the device filters packet delay variations and maintains
phase/time alignment with the Grandmaster, without the need
for PTP assistance in intermediary network nodes (such as
boundary clocks or transparent clocks).
Possible applications include:
Providing a network clock for circuit-emulation service
clock-recovery using differential timing (when conventional
network timing in PDH/TDM networks is available; or from
packet-timing).
Providing a 5 MHz, 10 MHz or chip-rate clock, allowing
wireless operators to migrate to packet-based backhaul
technology and eliminate T1/E1 interfaces, while
maintaining the required timing to all network elements.
Providing a 1 PPS signal which is aligned with the timebase
of a central Grandmaster clock.
This supports applications which require a common phase
to be available around a network (such as wireless
applications using TDD technologies).
At reset, the operating mode can be configured between the
TDM Timed, PTP Network Timed, Reference Timed and Self-
Test modes by a 2-bit SYSMODE port. In TDM Timed mode,
operation is identical to the ACS8520. In the network and
reference timed modes, master or slave operation occurs in
accordance with the PTP BMC algorithm or via configuration
(so that the device can operate with another clock-selection
mechanism).
In all modes except Self-Test, the ACS9510 has holdover and
free-run features for conditions when no references are
available. The stability of the output clocks during self-timing
activities depends on the performance of an external oscillator
that controls the internal clocks. The oscillator should be
chosen to suit the frequency accuracy and phase stability
requirements of the application.
In the network and reference timed modes, the ACS9510
performs all the functions required for a complete, stand-
alone, clock recovery system, including hardware time-
stamping, PTP protocol, network noise suppression, network
re-route accommodation and holdover, and provides outputs
for applications that require continuation of frequency, phase
and time. A serial peripheral interface compatible port is
provided to communicate with a host microprocessor for any
configuration and status monitoring that may be required.
Operationally the ACS9510 supports uni-cast communication,
and multi-cast PTP network addressing. Quality of service is
enhanced by configurable DiffServ codepoint for high priority
packet routing.
An API is provided for configuration and status monitoring. The
API offers system developers the means to produce
appropriate application software to configure and control the
ACS9510 and so integrate the required functionality from the
device into their synchronization scheme.
The ACS9510 requires 1 MB of SRAM and generic packet
PHYs with appropriate termination circuitry.
Principles of operation