QLX4600SIQSR Intersil, QLX4600SIQSR Datasheet - Page 19

• Manufacturer Part Number: QLX4600SIQSR
• Description: IC EQUALIZER REC 6.25GBPS 46QFN
• Manufacturer: Intersil

Specifications of QLX4600SIQSR

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Detection Threshold (DT) Pin Functionality
The QLx4600-S30 is capable of maintaining periods of
line silence on any of its four channels by monitoring
each channel for loss of signal (LOS) conditions and
subsequently muting the outputs of a respective channel
when such a condition is detected. A reference current
applied to the detection threshold (DT) pin is used to set
the LOS threshold of the internal signal detection
circuitry. Current control on the DT pin is done via one or
two external resistors. Nominally, both a pull-up and
pull-down resistor are tied to the DT pin (Figure 32A),
but if adequate control of the supply voltage is
maintained to within ±3% of 1.2V, then a simple
pull-down resistor is adequate (as in Figure 32B).
Resistors used should be at least 1/16W, with ±1%
precision.
The internal bias point of the DT pin, nominally 1.05V, is
used in conjunction with the voltage divider (R1 and R2)
shown in Figure 32A to set the reference current on the
DT pin.
Case 1: Channels with less than or equal to 25dB loss at
2.5GHz (1Gb/s to 6Gb/s):
Case 2: Channels with greater than 25dB loss at 2.5GHz
(1Gb/s to 6Gb/s):
For signals transmitted on channels having less than
or equal to 25dB of loss at 2.5GHz, the optimal DT
reference current is 0µA. This optimal reference
current may be achieved by either leaving the DT pin
floating, or tying the DT pin to ground (GND) with a
10MΩ resistor.
For channels exhibiting more than 25dB of total loss
(this includes cable or FR-4 loss) the DT pin should
be configured for a reference sink current (coming
out of the DT pin) of approximately 2µA. A typical
configuration for a 2µA sink current is given in
Figure 32C. If the configuration in Figure 32B is
utilized, a 525kΩ resistor would be used.
19
QLx4600-S30
FIGURE 32A.
FIGURE 32B.
FIGURE 32C.
FIGURE 32.
November 19, 2009
FN6979.1