MC34216A Datasheet, PDF (18/20 Pages) Motorola, Inc – PROGRAMMABLE TELEPHONE LINE INTERFACE CIRCUIT WITH LOUDSPEAKER AMPLIFIER

MC34216A
The MC34216A incorporates a DTMF generator with
integrated filters. The DTMF pairs can be selected by the
microcontroller via the MF bits. In this way, the whole DTMF
range for a 4x4 keyboard is available which fulfills the CCITT
requirements. The DTMF level on the line can be adjusted
by external components and it can also be programmed via
the MF bits.
For listening–in operation, the loudspeaker has to be
switched on and the anti–howling circuitry has to be
activated. The loudspeaker is switched on by making the
G2G1G0 bits high. They also set the volume. The
anti–howling circuit is activated by making bit HPI low. By
making bit Mth high, the microphone threshold feature is
enabled which further reduces the effect of howling.
By making the SP bit high, the speakerphone mode is
programmed. This automatically disables the earpiece by
muting the RXO2 output, and it enables the AHO1 input as a
speakerphone signal input. By making the MicP bit low, the
handset microphone is no longer powered and is thus muted.
This ensures that only the signal from the base microphone is
transmitted to the line.
By making the R/S bit high, the ringing mode is
programmed. The ringing melody is programmed via the
microcontroller and generated by the MC34216A. The
volume can be programmed via the 3 loudspeaker gain bits
G2G1G0. The ring melody is enabled by making the ring
tone switch RT high. The melody can be tested during
normal speech mode by activating the ring tone switch RT
while R/S is low.
The answering machine mode is entered by making the
R/S bit high. This enables the microphone, earphone and
loudspeaker amplifiers while the set is on–hook. This makes
it possible to record a message with the handset microphone
and to playback messages via the earpiece or loudspeaker.
Other blocks of the circuit are not activated. During off–hook
operation, the incoming messages can be recorded and the
outgoing message can be played in the normal way. More
details about the answering machine application can be
found in the user manual.
Support Material
Device Specification:
Brief description of the MC34216A,
block diagram, device data, bus
specification, test diagram, typical
application
User Manual MC34216A: Extended description of the circuit
and its concept, description of the
programmability, adjustment
procedure, application hints and
proposals
Demonstration Board:
Performance of the MC34216A is
shown in an application with the
TCA3385 switched mode power
supply and a MC68HC705
microcontroller
Adjustment Software:
A QBASIC program which helps
the customer to find the right
component values for fulfilling the
requirements
Register Display Board:
Visualizes the register contents
which are transmitted on the
demonstration board by means of
LEDs
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MOTOROLA ANALOG IC DEVICE DATA