SA2531 Datasheet, PDF (9/24 Pages) Sames – VERSATILE SINGLE CHIP TELEPHONE WITH 14 NUMBER REPERTORY DIALLER

KEYBORD ARRANGEMENT 2
SA2531 A/B/C/E/G/U
4 Direct and 10 Indirect memories
(either VOL or +/- keys)
Figure 3
Tone Ringer
The Tone Ringer of the SA2531 incorporates a Discriminator Circuit and adjustable Melody
Generator
Ring Frequency Discrimination
The Ring Frequency Discriminator assures that only signals with a frequency between
20Hz and 60Hz (option 13 Hz to 70 Hz) are regarded as valid ring signals.
When a valid ring signal is present for 73 ms continuously, the melody generator is
activated and remains active as long as the ring signal is present.
Once the melody generator has been started, the ring signal is continuously monitored
and the melody generator is instantly turned on or off according to the momentary
presence of a valid or unvalid ring signal respectively (until next POR of off-hook).
Melody Generator
When a Valid Ring Signal is detected the Melody generator is activated and creates a
ringing Signal comprising 3 frequencies F1 (800Hz), F2 (1067Hz) and F3 (1333Hz).
These frequencies are repeated in a sequence of 6 time slots constructed by the
frequencies
F1 F2 F3 F1 F2 F3
This seqeunce is repeated 1, 4, 7 or 10 times per second as indicated by the connection
of the RR Pin to one of the four rows of the keyboard.
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