u4091bm-r ATMEL Corporation, u4091bm-r Datasheet - Page 9

• Manufacturer Part Number: u4091bm-r
• Description: Programmable Telephone Audio Processor
• Manufacturer: ATMEL Corporation

9. DTMF Dialing
10. Melody and Confidence Tone Generation
4872A–CORD–08/05
The DTMF generator sends a multi-frequency signal through the matrix to the line. The signal is
the result of the sum of two frequencies and is internally filtered. The frequencies are chosen
from a low and a high frequency group. The circuit conforms to the CEPT recommendation con-
cerning DTMF option. Three different levels for the low level group and two different pre-
emphasis (2.5 dB and 3.5 dB) can be chosen by means of the serial bus (rec. T/CF 46-03).
Attention: In high gain mode, distortion can occur if AGATX is high and DC mask is low.
Melody and confidence tone frequencies are given in
The frequencies are provided at the DTMF input of the switch matrix. A sinusoidal wave, a
square wave or a pulsed wave can be selected by the serial bus. A square signal means the out-
put is high for half of the frequency cycle, and low for the other half. A pulsed signal means high
impedance phases of 1/6 of the period occur between the high and low phases.
Table 10-1.
Table 10-2.
Table 10-3.
Decimal
Decimal
Decimal
0
1
2
3
4
5
6
7
0
1
2
3
0
1
2
3
Status of Melody Generating
DTMF Frequencies
DTMF Frequencies
in DTMF Mode
in DTMF Mode
DTMFM[0:2]
DTMFF[0:1]
DTMFF[2:3]
000
001
010
011
100
101
110
111
00
01
10
11
00
01
10
11
DTMF generator OFF
Confidence tone melody on (sine)
Ringer melody (pulse)
Ringer melody (square signal)
DTMF (mid level)
DTMF (low level)
DTMF (high level)
–
Table
Frequency
Frequency
1209
1336
1477
1633
697
770
852
941
10-1.
Status
U4091BM-R
Error (%)
Error (%)
–0.007
–0.156
–0.110
–0.020
–0.182
0.032
0.316
0.123
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