ISL36111 Datasheet, PDF (6/8 Pages) Intersil Corporation – 11.1Gb/s Lane Extender

ISL36111
Internal LOS
Indicator
V_DD
11k Ω
LOSB
FIGURE 6. CML OUTPUT EQUIVALENT CIRCUIT FOR
THE ISL36111
Line Silence/Quiescent Mode
Line silence is commonly broken by the limiting
amplification in other equalizers. This disruption can be
detrimental in many systems that rely on line silence as
part of the protocol. The ISL36111 contains special lane
management capabilities to detect and preserve periods
of line silence while still providing the fidelity-enhancing
benefits of limiting amplification during active data
transmission. Line silence is detected by measuring the
amplitude of the input signal and comparing that to a
threshold set by the voltage at the DT pin. When the
amplitude falls below the threshold, the output driver
stage is muted.
LOS Bar Indicator
Pin 4 (LOSB) is used to output the state of the muting
circuitry to serve as a loss of signal indicator for the
device. This signal is directly derived from the muting
signal output by the detection threshold / signal detector
comparator. The LOSB signal goes LOW when the signal
detector output is below the externally controlled
detection threshold and HIGH when the detector output
goes above this threshold. This feature is meant to be
used in optical systems (e.g. SFP+) where there are no
quiescent or electrical-idle states. In these cases, the
detection threshold is used to determine the sensitivity of
the LOSB indicator. Figure 7 shows the schematic of the
LOSB equivalent output structure.
FIGURE 7. LOSB EQUIVALENT OUTPUT STRUCTUR
Detection Thereshold (DT) Pin
Functionality
The ISL36111 is capable of maintaining periods of line
silence by monitoring the channel for loss of signal (LOS)
conditions and subsequently muting the output driver
when such a condition is detected. A reference voltage
applied to the detection threshold (DT) pin is used to set
the LOS threshold of the internal signal detection
circuitry. The DT voltage is set with an external pull-up
resistor, R_DT. For typical applications, a 30kΩ resistor is
recommended for channels with loss greater than 12dB
at 5GHz, and a 1.8kΩ resistor is recommended for lower
loss channels. Other values of the resistor may also be
applicable; therefore DT settings should be verified on an
application-specific basis.
About Q:ACTIVE^®
Intersil has long realized that to enable the complex
server clusters of next generation datacenters, it is
critical to manage the signal integrity issues of electrical
interconnects. To address this, Intersil has developed its
groundbreaking Q:ACTIVE® product line. By integrating
its analog ICs inside cabling interconnects, Intersil is able
to achieve unsurpassed improvements in reach, power
consumption, latency, and cable gauge size as well as
increased airflow in tomorrow’s datacenters. This new
technology transforms passive cabling into intelligent
“roadways” that yield lower operating expenses and
capital expenditures for the expanding datacenter.
Intersil Lane Extenders allow greater reach over existing
cabling while reducing the need for thicker cables. This
significantly reduces cable weight and clutter, increases
airflow, and improves power consumption.
6
FN6974.0
November 19, 2009