MC33219A Datasheet, PDF (24/28 Pages) Motorola, Inc – Voice Switched Speakerphone

Freescale SMeCm33i2c1o9Anductor, Inc.
short, and the resistor and capacitor for each of these pins
should be physically close to the pins. All other input pins
should also be considered sensitive to RFI signals.
In The Final Analysis ...
Proper operation of a speakerphone is a combination of
proper mechanical (acoustic) design in addition to proper
electronic design.The acoustics of the enclosure must be
considered early in the design of a speakerphone. In
general, electronics cannot compensate for poor acoustics,
low speaker quality, low microphone quality, or any
combination of these items. Proper acoustic separation of
the speaker and microphone is essential. The physical
location of the microphone, along with the characteristics of
the selected microphone, will play a large role in the quality
of the transmitted sound. The microphone and speaker
vendors can usually provide additional information on the
use of their products.
In the final analysis, the circuit will have to be fine–tuned to
match the acoustics of the enclosure, the specific hybrid, and
the specific speaker and microphone selected. The
components shown in this data sheet should be considered
as starting points only. The gains of the transmit and receive
paths are easily adjusted at the microphone and receive
amplifiers, respectively. The switching response can then be
fine tuned by varying (in small steps) the components at the
level detector inputs (TLI, RLI) until satisfactory operation is
obtained for both long and short lines.
For additional information on speakerphone design please
refer to The Bell System Technical Journal, Volume XXXIX
(March 1960, No. 2).
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