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NTEGRATED
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LITELINK III Evaluation Board Users Guide
UG-CPC5622-EVAL-600R - Rev A
www.ixysic.com
5
Pin 8: RING2*
This is the full wave ringing detect output RING2 of the
CPC5622A. The output signal will be a logic low
whenever the incoming ringing signal exceeds the
threshold of the CPC5622A internal voltage detector.
With ringing applied, the output will be a series of
negative pulses at twice the frequency of the ringing
signal. The width of the negative pulses will be a
function of the ringing signal amplitude.
Pin 9: RING*
This is the half-wave ringing detect output RING of the
CPC5622A. The description of this output signal is
similar to RING2 above but the output pulses will have
the same frequency as the incoming ringing signal.
Pin 10: LIU*
LIU* is a logic level output indicating an off-hook by
another device on tip and ring whenever the
CPC5622A is on-hook. With a T/R voltage less than
approxi/-14V
DC
an Off-Hook indication
(LIU* = 0) is output. For tip to ring voltages greater
than approxi/-17V
DC
the detector will output a
logic high (LIU* = 1). As with the LOOP detector, the
LIU* detector is polarity insensitive.
Declaring the line to be Off-Hook when LIU* = 0 is
only valid when loop battery is present, LOOP = 1.
Pin 11: GND
This is the low voltage side (SELV) ground. All low
voltage side signals are referenced from this net. The
tip and ring voltages as well as the line side signals
are NOT referenced from the low voltage side ground.
Pin 12: POLARITY
POLARITY is a logic level output that indicates the
polarity of the battery feed on tip and ring.
POLARITY = 1 for normal battery when the Tip is
more positive than the Ring. When the battery polarity
is reversed causing Ring to be more positive than Tip,
the detector will output POLARITY = 0. The
POLARITY detector nominal thresholds are set at
2V
DC
.
The POLARITY detector does not change state until
the increasing line voltage potential passes through
the switching point. This ensures the POLARITY
detector output will remain stable at it’s last state if
battery feed from the network is lost.
3.3 Tip to Ring Conditioning
When using the CPC5622 evaluation board, the tip to
ring interface must be properly configured with DC
bias for off-hook AC transmission as the CPC5622 line
side circuitry derives it’s operating power from the
network. In addition, the CPC5622 must have a tip to
ring AC termination impedance equal to the evaluation
board’s two-wire input impedance for correct analog
transmission performance. The required tip to ring
termination impedance for the CPC5622-EVAL-600R
evaluation board is 600
.
For basic functional testing, the tip and ring may be
connected to an external PSTN line. While these lines
provide DC bias and an acceptable AC termination for
access to the network, they are not suitable for lab
quality measurements.
General purpose evaluations can be made using a
phone line simulator, also known as a Central Office
(CO) line simulator, to source the DC loop current and
to provide a reasonable AC impedance. Using a line
simulator rather than an external PSTN line eliminates
the variable AC impedance and DC feed
characteristics caused by the outside cable plant.
Lab quality measurements are typically made using a
DC feed circuit conforming to industry standards and
test equipment specific for voice quality testing.
3.4 Analog Transmission
The UG-CPC5622-EVAL-600R evaluation board
supports full duplex analog voice transmission while
off-hook and receive transmission only when on-hook.
The nominal gains for all of these transmission paths
is 0dB.
3.5 Loop Status Detectors
In addition to the basic ringing detector provided by
the CPC5622A, this evaluation board includes
additional detectors to determine the status of the
loop. Many telephony products need to know the line’s
condition to function properly. For instance, an
automated calling out device would need to know if the
line is available or is currently being used by another
piece of equipment while another type of product may
need to know if it is about to receive a Caller-ID (CID)
transmission. These and other conditions can be
derived by monitoring the Tip to Ring voltage and