CPC5710N

R03

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5

2. Using CPC5710N

2.1 LIN/CMP Input

The LIN/CMP input selects the active output, either

the detector output CMPOUT or the linear outputs,

LINOUT- and LINOUT+. Set LIN/CMP low for linear

output and high for comparator output. Note that both

outputs cannot be used at once.

With LIN/CMP at logic low (LIN/CMP = 0), the

CMPOUT is held high. With LIN/CMP at logic high

(LIN/CMP = 1), LINOUT+ is 0V and LINOUT- is 2V.

Figure 1. LIN/CMP Timing for Caller-ID Signal

Reception

2.2 Amplifier Design

Considerations

internal voltage reference. The internal common-mode

circuitry maintains the average of the inputs at

common-mode circuit drives the other input to 1.2V.

2.2.1 Linear Amplifier Gain

Display feature information (caller ID) and voice

signals are coupled through the linear amplifier. In

North America, CID data signals are typically sent

between the first and second ringing signal burst.

Referring to Figure 5., signal gain from tip and ring to

LINOUT+ and LINOUT- is determined by:

where

Application Note AN-117 Customize Caller ID Gain and

Ringing Detect Voltage Threshold is a spreadsheet for

trying different component values in this type of circuit.

2.3 Detector Considerations

2.3.1 Ringing Signal Detection

The CPC5710N detector is a full-wave configuration.

Ringing signals will assert the output on both positive

and negative parts of the ringing waveform. Hysteresis

is employed by the internal comparator circuit to

provide noise immunity. The set-up of the detector

causes CMPOUT output pulses to remain low for most

of the ringing signal positive and negative half-cycles.

CMPOUT returns high when the ringing signal is near

the zero-voltage crossing.

Figure 2. CMPOUT Relative to Input

2.3.2 Setting Ringing Detection Threshold

The ringing detection threshold depends on the

component values of the input network. The values for

these components shown in the application circuit are

recommended for typical operation. Referring to

Figure 5., the ringing detection threshold can be

changed according to the following formula:

Caller ID data

LIN/CMP

Signal levels not to scale

2s

500 ms

3s

475 ms

2s



20

+



2

1

fC

SNP



2

--------------------------

+

-----------------------------------------------------------------------------------------

log

=

CMPOUT

Ringing Signal

750mV

-------------------





+



2

1

f



2

--------------------------------------

+

=