CPC5620 Datasheet, PDF (11/18 Pages) Clare, Inc. – LITELINK III Phone Line Interface IC (DAA)

INTEGRATED CIRCUITS DIVISION
half-cycle of the ringing signal for the CPC5620. For
the CPC5621, the RING output returns high for a short
period near the zero-crossing of the ringing signal
before returning low during the positive half-cycle. For
both the CPC5620 and CPC5621, the RING output
remains high between ringing signal bursts.
The ringing detection threshold depends on the values
of R3 (R_SNPD), R6 & R44 (R_SNP-), R7 & R45 (R_SNP+),
C7 (C_SNP-), and C8 (C_SNP+). The value of these
components shown in the application circuits are
recommended for typical operation. The ringing
detection threshold can be changed according to the
following formula:
V_RINGPK
=


7-_{R---5-S--0-N--}m_-P---D-V_{--}
R_SNPTOTAL + R_SNPD² + _---_----_f--_R---_I--_N---_G-1---_C----_S---_N---_P---_---₂
Where:
• R_SNPD = R3 in the application circuits shown in this
data sheet.
• RSNP_TOTAL = the total of R6, R7, R44, and R45 in
the application circuits shown in this data sheet.
• C_SNP = C7 = C8 in the application circuits shown in
this data sheet.
• And ƒ_RING is the frequency of the ringing signal.
IXYS Integrated Circuits Division Application Note
AN-117 Customize Caller ID Gain and Ring Detect Voltage
Threshold is a spreadsheet for trying different
component values in this circuit. Changing the ringing
detection threshold will also change the caller ID gain
and the timing of the polarity reversal detection pulse,
if used.
3.2.2 Polarity Reversal Detection with
CPC5621 in On-hook State
The full-wave ringing detector in the CPC5621 makes
it possible to detect on-hook tip and ring polarity
reversal using the RING output. When the polarity of
tip and ring reverses, a pulse on RING indicates the
event. Your system logic must be able to discriminate
this single pulse of approximately 1 msec (using the
recommended snoop circuit external components)
from a valid ringing signal.
CPC5620/CPC5621
3.2.3 On-hook Caller ID Signal Reception
On-hook caller ID (CID) signals are processed by
LITELINK by coupling the CID data burst through the
snoop circuit to the LITELINK RX outputs under
control of the CID pin. In North America, CID data
signals are typically sent between the first and second
ringing signal.
In North American applications, follow these steps to
receive on-hook caller ID data via the LITELINK RX
outputs:
1. Detect the first ringing signal outputs on RING.
2. Assert CID low.
3. Process the CID data from the RX outputs.
4. De-assert CID (high or floating).
Note: Taking LITELINK off-hook (via the OH pin)
disconnects the snoop path from both the receive
outputs and the RING output, regardless of the state
of the CID pin.
CID gain from tip and ring to RX+ and RX- is
determined by:
GAIN_CIDdB = 20log ---------------------------------------6---^R----^S---^N----^P---^D----------------------------------------
R_SNPTOTAL + R_SNPD² + _---_----_f--_C---1-_S---_N---_P---_--₂-
Where:
• R_SNPD = R3 in the application circuits in this data
sheet
• RSNP_TOTAL = the total of R6, R7, R44, and R45 in
the application circuits in this data sheet
• C_SNP = C7 = C8 in the application circuits in this data
sheet
• and where ƒ is the frequency of the CID signal
The recommended components in the application
circuit yield a gain 0.27 dB at 2000 Hz. IXYS
Integrated Circuits Division Application Note AN-117
Customize Caller ID Gain and Ring Detect Voltage Threshold
is a spreadsheet for trying different component values
in this circuit. Changing the CID gain will also change
the ring detection threshold and the timing of the
polarity reversal detection pulse, if used.
R05
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