AS2534BT Austriamicrosystems, AS2534BT Datasheet - Page 8

• Manufacturer Part Number: AS2534BT
• Description: AS Series 3.8 to 5V Multi-Standard CMOS Telephone IC for Basic Telephone SOIC-28
• Manufacturer: Austriamicrosystems

Data Sheet
DTMF
The DTMF generator provides 8 frequencies, namely:
Low group
High group
The MF output level can be set with an external voltage
divider on pin MFL.
Voltage at pin MFL (2)
(Z
The preemphasis is 2.6 dB.
The MF tones are according to CEPT recommendations.
Tone Ringer (Melody/Volume)
The three basic frequencies of the melodies are:
F1 = 800 Hz, F2 = 1067 Hz, and F3 = 1333 Hz ( 5%).
The repetition rate and the volume of the tone ringer
melodies can be programmed by pressing P/M and #
followed by a digit as follows (not AS2534E):
Rev. 7
LINE
= 600 ohm)
Digit 1-2-3-A
Digit 4-5-6-B
Digit 7-8-9-C
Digit * -0-# -D
Digit 1-4-7- *
Digit 2-5-8-0
Digit 3-6-9-#
Digit A-B-C-D
Digit Repetition Rate
1
2
3
4
5
6
7
8
9
0
1.50 V (A
1.27 V
1.15 V
1.03 V
0.90 V
0.70 V
0.54 V
0.42 V
0.30 V
0.18 V
0.00 V (V
1 time (50 ms pause)
1 time (50 ms pause)
1 time (50 ms pause)
4 time s
4 times
4 times (default)
10 times
10 times
10 times
None
GND
SS
)
)
697 Hz
770 Hz
852 Hz
941 Hz
1209 Hz
1336 Hz
1477 Hz
1633 Hz (not AS2535)
DTMF Level (Low Group)
-4.0 dBm
-5.2 dBm
-6.4 dBm
-7.6 dBm
-8.8 dBm
-10.0 dBm
-11.2 dBm
-12.4 dBm
-13.6 dBm
-14.8 dBm
-16.0 dBm
Volume
- 16 dB
- 7 dB
0 dB (max.)
- 16 dB
- 7 dB
0 dB (max.)
- 16 dB
- 7 dB
0 dB (max.)
Off
8
The procedure is ended by repressing the P/M key.
The default setting is digit 6, i.e. after a power on reset
the device will start up with repetition rate 4 and maximum
volume. If digit 0 is programmed, the tone ringer will be
turned off until next off-hook where it will turn back to the
last setting before 0. The programmed settings are
stored in the on chip RAM.
Repetition rate means that a sequence of 6 frequencies
is repeated 1, 4 or 10 times within 1 second.
The sequence of the frequencies is controlled by the
sequence register as follows:
The AS2534E is fixed to default settings and can not be
programmed to other settings.
Pacifier Tone
By MF dialling the DTMF tones are provided to the
earpiece as comfort tone.
During programming a key entry is acknowledged by a
pacifier tone of 1477 Hz. The level of the pacifier tone is
approximately 60 mV at the RO output. The duration is
40 ms after every key entry in programme mode.
When terminating the programme mode with the P/M
key an acknowledge tone of 140 ms is provided. An
invalid key entry, however, will cause a termination of
the programme mode indicated by a rejection tone of 4
times 40 ms with 28 ms pauses between the tone bursts.
Ring Frequency Discrimination
The ring frequency discriminator assures that only signals
with a frequency between 13Hz and 70 Hz are regarded
as valid ring signals. The time for recognising a valid ring
signal is 1/f seconds, where 'f' is the ring frequency.
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 or off-hook).
Sequence
F1 F2 F3 F1 F2 F3 …
AS2533...6
July 1998