75T2089 View Datasheet(PDF) - TDK Corporation
Part Name
Description
Manufacturer
75T2089 Datasheet PDF : 9 Pages
| |||
RECEIVER OUTPUTS AND THE DE PIN
Outputs D0, D1, D2, D3 are CMOS push-pull when
enabled (DE low) and open-circuited (high
impedance) when disabled (DE high). These digital
outputs provide the hexadecimal code
corresponding to the detected digit. Figure 3 shows
that code.
The digital outputs become valid and DV signals a
detection after a valid tone pair has been sensed.
The outputs and DV are cleared when a valid pause
has been timed.
Hexadecimal Code
Digit In
D7
D6
D5
D4
Out D3
D2
D1
D0
1
0
0
0
1
2
0
0
1
0
3
0
0
1
1
4
0
1
0
0
5
0
1
0
1
6
0
1
1
0
7
0
1
1
1
8
1
0
0
0
9
1
0
0
1
0
1
0
1
0
*
1
0
1
1
#
1
1
0
0
A
1
1
0
1
B
1
1
1
0
C
1
1
1
1
D
0
0
0
0
FIGURE 3
75T2089/2090/2091
DTMF Transceivers
ED OUTPUT (75T2091 only)
The ED output goes high as soon as the 75T2091
begins to detect a DTMF tone pair and falls when the
75T2091 begins to detect a pause. The D1, D2, D4,
and D8 outputs are guaranteed to be valid when DV
is high, but are not necessarily valid when ED is high.
GENERATOR
The DTMF generator responds to a hexadecimal
code input with a valid tone pair. Pins D4-D7 are the
data inputs for the generator. A high to low transition
on LATCH causes the hexadecimal code to be
latched internally and generation of the appropriate
DTMF tone pair to begin. The DTMF output is
disabled by a high on RESET and will not resume
until new data is latched in.
DIGITAL INPUTS
The D4, D5, D6, D7, LATCH, RESET inputs to the
DTMF generator may be interfaced to open-collector
TTL with a pull-up resistor or standard CMOS. These
inputs follow the same hexadecimal code format as the
DTMF receiver output. Figure 4 shows the code for
each digit. The dialing matrix and detection frequency
table below list the frequencies of the digits.
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
NOTE: Column 3 is for special applications
and is not normally used in telephone dialing.
FIGURE 4: DTMF Dialing Matrix
DETECTION FREQUENCY
Low Group f
0
Row 0 = 697Hz
Row 1 = 770Hz
Row 2 = 852Hz
Row 3 = 941Hz
High Group f
0
Column 0 = 1209Hz
Column 1 = 1336Hz
Column 2 = 1477Hz
Column 3 = 1633Hz
3
Share Link: 