73M1906B-IVT/F Maxim Integrated Products, 73M1906B-IVT/F Datasheet - Page 73

• Manufacturer Part Number: 73M1906B-IVT/F
• Description: Interface - Specialized DAA-FXO VolP SYSTEM HOST SIDE
• Manufacturer: Maxim Integrated Products
• Type: MicroDAA with PCM Highwayr

Specifications of 73M1906B-IVT/F

• Operating Supply Voltage: 3.3 V
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Package / Case: QFN-32
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

DS_1x66B_001
11 Line Sensing and Status
The 73M1x66 supports the means to implement several line status functions such as ring detection, Line
In Use detection, parallel pickup detection, and line voltage polarity reversals. To support these
functions, 73M1x66 is able to measure the line voltage and current characteristics. In conjunction with
these measurements, procedures can be implemented in the host to fully support these capabilities in an
application.
11.1 Auxiliary A/D Converter
An 8-bit auxiliary A/D converter integrated in the 73M1x66B provides line monitoring and sensing
capabilities. The A/D converter input signals are connected to the RGP and RGN pins of the device. It is
possible to use this A/D converter to sample signals unrelated to PSTN DAA functions. However, in this
application, it is necessary to isolate the input signal with optical or other means since the 73M1x66B is
connected directly to the PSTN. Under normal conditions, RGP and RGN are AC coupled to the line
through high voltage (250 V) capacitors.
Through the use of this auxiliary A/D converter, the following line status sensing features are supported
by the 73M1x66B:
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11.2 Ring Detection
Ring Detection is provided through circuitry connected to the device pins RGP and RGN. Any large
voltage transition (ringing or line reversal) will be a source for the “Wake up” signal to the 73M1x66B.
Upon reception of a wake-up signal, the 73M1x66B passes the detected signal to the host where it is to
be qualified for frequency and cadence (on and off timing of the ring tone bursts) as a valid ring signal.
11.3 Line In Use Detection (LIU)
If the 73M1x66B is preparing to go off-hook and dial, it is required to be aware whether the phone line is
already in use by another device. If the 73M1x66B determines that the phone line is presently in use, it
can avoid going off-hook and interrupting the call in progress. The timing of the FXO’s off-hook transition
can be delayed until the FXO determines that the phone line is available. LIU sensing is done at pin
DCIN with the Aux A/D.
11.4 Parallel Pick Up (PPU)
Parallel Pick Up is a means for the 73M1x66B to determine and notify a host in the case when the DAA is
off-hook and a second or parallel-connected device during the course of a connection is also made to go
off-hook.
11.5 Polarity Reversal Detection
A third type of line sensing requirement is associated with Caller ID protocols found in Japan and some
European countries. In these countries, the Caller ID signals are sent prior to the start of normal ringing.
A polarity reversal is used to indicate to the FXO that transmission of Caller ID information is about to
begin. The detection of a polarity reversal takes place while the FXO is in the on-hook state.
11.6 Off-hook Detection of Caller ID Type II
It is also possible to receive Caller ID signals while the telephone is in use, referred to as Type II CID.
This requires the 73M1916 to constantly monitor the line for signals, such as special in-band or CAS
tones, while the FXO is in the off-hook state. This is done through the normal receive path.
Rev. 1.6
Ring detection.
PSTN line already in use detection.
Off-hook detection that a parallel phone has been picked-up – parallel pick-up detection (PPU).
On-hook detection of DC loop voltage polarity reversals.
On-hook detection of Type II Caller ID.
73M1866B/73M1966B Data Sheet
73