CML Semiconductor Products
PRODUCT INFORMATION
FX465
Features
Low-Voltage (3-Volt) Supply
47 Programmable Sub-Audio
Tones + N
OTONE
Meets MPT1306 and TIA/EIA 603
High Voiceband/CTCSS Isolation
Separate Sub-Audio and Rx/Tx
Audio Paths and Filtering
TONE IN
FILTER
TONE IN
TONE DECODE
FILTER
Extended Code CTCSS
Encoder/Decoder
Applications
Mobile Radio Systems
Publication D/465/2 May 1996
Advance Information
Community Base Stations
鈥淪ports Radio鈥?(Japan)
Sub-Audio Signalling and
Selective Calling
Status and Alarm Systems
Amateur Radio
REFERENCE
VOLTAGE
+
-
f
TONE
CLKS
CLKS
-
+
LOAD/LATCH
D5/SERIAL ENABLE
D4/SERIAL ENABLE
D3/SERIAL DATA IN
D2/SERIAL CLOCK
D1
D0
RX/TX
PTL
XTAL/CLOCK
XTAL
AND
CLOCK
GENERATION
A0 - A5
D0 - D10
48 x 10
TONE
V
DD
ROM
V
SS
V
BIAS
CLKS/XTAL
Tx TONE OUT
DIGITAL
INTERFACE
CLKS/XTAL
TONE DETECT
LOGIC
TONE OUT FILTER
Rx TONE DETECT
FX465
CLK
TX AUDIO IN
Tx AUDIO OUT
RX AUDIO IN
AUDIO FILTER
Rx AUDIO OUT
DECODE COMPARATOR REF
DECODE COMPARATOR IN
+
-
Rx TONE DECODE
Fig.1 Functional Block Diagram
New SSOP
D5
package
The Rx sub-audio (CTCSS) path contains a
(selected tone frequency) bandpass filter and period
detector providing a logic level output (Rx Tone Detect)
to indicate a successful decode operation.
Rx 鈥淧ress to Listen鈥?(PTL) and Tx 鈥淪quelch-Tail
Elimination鈥?functions are available in both command
loading modes. The squelch-tail elimination function
will provide (Tx tone) phase-reversal to minimise the
annoying audio outputs that occur at the receiver on
completion of a transmission.
Tone frequencies and filter accuracies are
maintained by an on-chip 4.0MHz clock oscillator
employing an external crystal or clock pulse input.
The FX465, which exhibits high audio and sub-audio
performance with low falsing, is available in a 24-pin
plastic small outline SSOP package.
Brief Description
The FX465 is a 3-volt, half-duplex predictive
Continuous Tone Controlled Squelch System (CTCSS)
encoder/decoder microcircuit. The FX465 has integral
voice-band filtering for prefiltering of Tx audio and the
rejection of the CTCSS tone in receive.
Under 碌Processor control, the FX465 will encode
and decode any one of 47 sub-audio frequencies
(+N
OTONE
) in the range 67.0Hz to 254.1Hz. Tone
frequencies and all functional commands can be
loaded to the device in either pin-selectable 8-bit
parallel or serial format.
A separate, Rx/Tx voice-audio path is available with
a highpass (sub-audio reject) filter automatically placed
in the relevant Rx or Tx voice line.
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