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LITELINK III Evaluation Board Users Guide
UG-CPC5622-EVAL-600R - Rev A
www.ixysic.com
3
2.2 Using the Evaluation Board
Follow these guidelines for productive use of the LITELINK evaluation board:
•
Evaluation board circuit components are sensitive to
electrostatic discharge (ESD). Use normal ESD
precautions when working with the LITELINK III
evaluation board.
•
Make all low voltage side connections (J2) to the
board before applying power to VCC.
Tip and Ring connections at J1 can be made at any
time before or after VCC power is applied.
•
OH* should be open or tied to the VCC input power
pin during power up and held for 50us after power
up.
•
Pulling OH* low will cause the CPC5622 to go
off-hook and returning OH* high will cause the unit to
go back on-hook.
•
Analog transmission in both the transmit path and
the receive path is enabled while off-hook. When
on-hook, only the receive path is enabled.
•
For proper off-hook operation, the Tip and Ring
interface must be appropriately biased and
terminated.
•
The CPC5622 RING* and RING2* ringing detectors
are only active while on-hook.
•
The CPC5712U line voltage and polarity detectors
are active in both the on-hook and off-hook states.
3. Functional Description
The CPC5622-EVAL-600R provides the analog
interface and signaling functions necessary to
implement a PSTN two-wire terminating device for
voice and data applications such as PBX FXO,
cordless telephones, FAX machines, set top boxes,
card readers, ATMs, and modems. Analog gains in
both the transmit and receive paths for the 600R
evaluation board are set to 0dB with the impedance of
the two-wire interface configured for 600 ohms
resistive. These analog functions are provided by the
CPC5622A Phone Line Interface integrated circuit.
Additionally, the CPC5622A provides the basic
signaling functions of loop closure / loop open and
ringing detect that are required for a two-wire, current
sink, loop start interface. It is important to note that it is
not within the scope of this document to provide
complete behavioral descriptions of the CPC5622A or
the CPC5712U functions as this information is
covered in the data sheets and the appropriate
application notes.
Basic signaling functions for a loop start, current sink
interface are loop closure (Off-Hook), loop open
(On-Hook) and ringing detect. Loop closure / open is
provided by the hook switch control function with
ringing detect provided by the Snoop input circuit and
the internal ringing detector. Additional loop voltage
detectors used to determine the line status are
provided by the CPC5712U Voltage Monitor with
Detectors integrated circuit. Line condition status
provided by the CPC5712U voltage detectors are:
Line In Use (LIU), Loop battery presence (LOOP), and
Polarity. While these detectors are not required for the
most basic applications, they are required by the
majority and are therefor provided on the evaluation
board. Access to the analog paths and the detector
functions is provided by the two connectors J1 and J2.
Tip and Ring loop access is provided by J1 while J2
provides access to the low voltage side (SELV) power
and signals.