MC33219A Datasheet, PDF (26/28 Pages) Motorola, Inc – Voice Switched Speakerphone

Freescale SMeCm33i2c1o9Anductor, Inc.
Return Loss – Expressed in dB, it is a measure of how
well the telephone’s AC impedance matches the line’s AC
characteristic impedance. With a perfect match, there is no
reflected signal, and therefore infinite return loss. It is
calculated from:
+ RL 20
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(ZLINE
(ZLINE
ZCKT)
ZCKT )
Ring – One of the two wires connecting the central office
to a telephone. The name is derived from the ring portion of
the plugs used by operators (in older equipment) to make the
connection. Ring is traditionally negative with respect to Tip.
Sidetone Rejection – The rejection (in dB) of the reflected
signal in the receive path resulting from a transmit signal
applied to the phone and phone line.
SLIC – Subscriber Line Interface Circuit. It is the circuitry
within the CO or PBX which connects to the user’s phone
line.
Subscriber – The customer at the telephone end of the
line.
Subscriber Line – The system consisting of the user’s
telephone, the interconnecting wires, and the central office
equipment dedicated to that subscriber (also referred to as
a loop).
Tip – One of the two wires connecting the central office to
a telephone. The name is derived from the tip of the plugs
used by operators (in older equipment) to make the
connection. Tip is traditionally positive with respect to Ring.
Transmit Path – Within the telephone it is the speech
path from the microphone towards the phone line (Tip and
Ring).
Two Wire Circuit – Refers to the two wires connecting the
central office to the subscriber’s telephone. Commonly
referred to as Tip and Ring, the two wires carry both transmit
and receive signals in a differential manner.
Two–to–Four Wire Converter – A circuit which has four
wires (on one side): two (signal and ground) for the outgoing
signal and two for the incoming signal. The outgoing signal is
sent out differentially on the two wire side, and incoming
differential signals received on the two wire side are directed
to the receive path of the four wire side. Additional circuit
within cancels the reflected outgoing signal to keep it
separate from the incoming signal.
Voiceband – That portion of the audio frequency range
used for transmission across the telephone system. Typically
it is 300–3400 Hz.
Suggested Vendors
Microphones
Primo Microphones Inc.
Bensenville, IL 60106
1–800–76–PRIMO
Telecom Transformers
Microtran Co., Inc.
Valley Stream, NY 11528
516–561–6050
Various models – ask for catalog
and Application Bulletin F232
Stancor Products
Logansport, IN 46947
219–722–2244
Various models – ask for catalog
PREM Magnetics, Inc.
McHenry, IL 60050
815–385–2700
Various models – ask for catalog
Motorola does not endorse or warrant the suppliers referenced.
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