CD22204(1999) 데이터 시트보기 (PDF) - Intersil
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CD22204 Datasheet PDF : 5 Pages
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CD22204
3.579545MHz
XIN
10
ATB
11
1M
XOUT
VDD
9
CD22204
6
XEN
XIN CONNECTED TO VDD
10
11
CD22204
XEN
6
UP TO 10 DEVICES
FIGURE 2. CRYSTAL OSCILLATOR
Outputs D1, D2, D4, D8 and EN
Outputs D1, D2, D4, D8 are CMOS push-pull when enabled
(EN high) and open circuited (high impedance) when dis-
abled by pulling EN low. These digital outputs provide the
hexadecimal code corresponding to the detected digit. The
digital outputs become valid after a tone pair has been
detected and they are then cleared when a valid pause is
timed. The table below describes the hexadecimal codes.
TABLE 1. OUTPUT CODES
DIGIT
D8
D4
D2
D1
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
DV
DV signals a detection by going high after a valid tone pair is
sensed and decoded at the output pins D1, D2, D4, and D8.
DV remains high until a valid pause occurs.
N/C Pin
This pin has no internal connection and should be left floating.
DTMF Dialing Matrix
COL 0
1209Hz
COL 1
1336Hz
COL 2
1477Hz
COL 3
1633Hz
ROW 0
697Hz
1
2
3
A
ROW 1
770Hz
4
5
6
B
ROW 2
852Hz
7
8
9
C
ROW 3
941Hz
*
0
#
D
NOTE: Column 3 is for special applications and is not normally used
in telephone dialing.
Digital Inputs and Outputs
All digital inputs and outputs of the DTMF receivers are rep-
resented by the schematic below. Only the “analog in” pin is
different, and is described above. Care must be exercised
not to exceed the voltage or current ratings on these pins as
listed in the “maximum ratings” section.
VDD
DIGITAL
INPUT
CMOS
DIGITAL
CIRCUITRY
DIGITAL
OUTPUT
VSS
FIGURE 3. DIGITAL INPUTS AND OUTPUTS
Input Filter
The CD22204 will tolerate total input noise of a maximum
of 12dB below the lowest amplitude tone. For most
telephone applications, the combination of the high
frequency attenuation of the telephone line and internal
band limiting make special circuitry at the input to these
receivers unnecessary. However, noise near the 56kHz
internal sampling frequency will be aliased (folded back)
into the audio spectrum, so if excessive noise is present
above 28kHz, the simple RC filter shown below may be
used to band limit the incoming signal. The cut off
frequency is 3.9kHz.
NOISY
SIGNAL
270kΩ
0.0015µF
ANALOG
IN
33kΩ
CD22204
FIGURE 4. FILTER FOR USE IN EXTREME HIGH FREQUENCY
INPUT NOISE ENVIRONMENT
70
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