Description
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The 75T202 and 75T203 are complete Dual-tone Multifrequency (DTMF) receivers detecting a selectable group of 12 or 16 standard digits.
Features
* Central office quality NO front-end band-splitting filters required Single, low-tolerance, 5-volt supply Detects either 12 or 16 standard DTMF digits Uses inexpensive 3.579545 MHz crystal fo
Applications
* and is not normally used in telephone dialing. Col 0 Row 0 1 Col 1 2 Col 2 3 Col 3 A
Row 1
4
5
6
B
Row 2
7
8
9
C
Row 3
* 0
#
D
FIGURE 3: DTMF Dialing Matrix
DETECTION FREQUENCY Low Group f0 Row 0 = 697 Hz Row 1 = 770 Hz Row 2 = 852 Hz Row 3 = 941 Hz High Group f0 Column 0 = 1209
