MT8880CE1 Zarlink, MT8880CE1 Datasheet - Page 7

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MT8880CE1

Manufacturer Part Number
MT8880CE1
Description
DTMF TXRX 3.58MHz CMOS 5V 20-Pin PDIP Tube
Manufacturer
Zarlink
Datasheet

Specifications of MT8880CE1

Package
20PDIP
Operating Frequency
3.58 MHz
Typical Supply Current
11 mA
Typical Operating Supply Voltage
5 V
Minimum Operating Supply Voltage
4.75 V
Maximum Operating Supply Voltage
5.25 V

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DTMF Generator
The DTMF transmitter employed in the MT8880C is capable of generating all sixteen standard DTMF tone pairs
with low distortion and high accuracy. All frequencies are derived from an external 3.579545 MHz crystal. The
sinusoidal waveforms for the individual tones are digitally synthesized using row and column programmable
dividers and switched capacitor D/A converters. The row and column tones are mixed and filtered providing a
DTMF signal with low total harmonic distortion and high accuracy. To specify a DTMF signal, data conforming to the
encoding format shown in Figure 7 must be written to the transmit Data Register. Note that this is the same as the
receiver output code. The individual tones which are generated (f
High Group tones. As seen from the table, the low group frequencies are 697, 770, 852 and 941 Hz. The high group
frequencies are 1209, 1336, 1477 and 1633 Hz. Typically, the high group to low group amplitude ratio (pre-
emphasis) is 2 dB to compensate for high group attenuation on long loops.
F
697
697
697
770
770
770
852
852
852
941
941
941
697
770
852
941
LOW
Figure 7 - Functional Encode/Decode Table
F
1209
1336
1477
1209
1336
1477
1209
1336
1477
1336
1209
1477
1633
1633
1633
1633
0= LOGIC LOW, 1= LOGIC HIGH
HIGH
Zarlink Semiconductor Inc.
MT8880C
DIGIT
A
B
C
D
1
2
3
4
5
6
7
8
9
0
*
#
7
D
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
3
LOW
D
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
2
and f
D
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
HIGH
1
) are referred to as Low Group and
D
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
0
Data Sheet

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