67
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
http://www.intersil.com or 407-727-9207 | Copyright Intersil Corporation 1999
CD22204
5V Low Power Subscriber DTMF Receiver
The CD22204 complete dual tone multiple frequency (DTMF)
receiver detects a selectable group of 12 or 16 standard digits.
No front-end pre-filtering is needed. The only externally
required components are an inexpensive 3.579545MHz TV
``colorburst'' crystal (for frequency reference) and a bias
resistor. Extremely high system density is possible through
the use of the Alternate Time Base (ATB) output of a crystal
connected CD22204 receiver to drive the time bases of up to
10 additional receivers. This is a monolithic integrated circuit
fabricated with low power, complementary symmetry CMOS
processing. It only requires a single power supply.
The CD22204 employs state-of-the-art ``switched-capacitor''
filter technology, resulting in approximately 40 poles of filtering
and digital circuitry on the same CMOS chip. The analog input
is preprocessed by 60Hz reject and bandsplitting filters and
then zero-cross detected to provide AGC. Eight bandpass
filters detect the individual tones. Digital processing is used to
measure the tone and pause durations and provides the
correctly coded and timed digital outputs. The outputs
interface directly to standard CMOS circuitry and are three-
state enabled to facilitate bus oriented architectures.
Functional Diagram
Features
No Front End Band Splitting Filters Required
Single Low Tolerance 5V Supply
Three-State Outputs for Microprocessor Based
Systems
Detects all 16 Standard DTMF Digits
Uses Inexpensive 3.579545MHz Crystal
Excellent Speech Immunity
Output in 4-Bit Hexadecimal Code
Excellent Latch-Up Immunity
Pinouts
CD22204 (PDIP)
TOP VIEW
Ordering Information
PART
NUMBER
TEMP.
RANGE (
o
C)
PACKAGE
PKG. NO.
CD22204E
0 to 70
14 Ld PDIP
E14.3
HIGH B/P
FILTERS
LOW B/P
FILTERS
VOLTAGE
REG./REF.
CLOCK
GENERA
T
O
R
CHIP
CLOCKS
ATB
XEN
11
6
10
9
4
8
DETECT
ORS AND SIGNAL-
PR
OCESSING CIRCUITS
5
12
2
1
14
13
3
DV
D1
D4
D8
EN
XIN
XOUT
D2
V
SS
V
DD
PREPR
OCESSOR/
B
ANDSPLIT FIL
TER
ANALOG IN
7
NC
NOTE: Pin numbers are for PDIP.
D2
D1
EN
V
DD
NC
XEN
ANALOG
D4
D8
DV
ATB
XIN
XOUT
V
SS
1
2
3
4
5
6
7
14
13
12
11
10
9
8
IN
Data Sheet
February 1999
File Number
1696.4
68
Absolute Maximum Ratings
(Note 1)
Thermal Information
DC Supply Voltage (V
DD
) (Referenced to V
SS
Terminal) . . . . . . .7V
Power Dissipation
T
A
= 25
o
C (Derate above T
A
= 25
o
C at 6.25mW/
o
C . . . . . . . .65mW
Input Voltage Range
All Inputs Except Analog In . . . . . . . . . . . . . . (V
DD
0.5V) to -0.5V
Analog in Voltage Range . . . . . . . . . . . . . (V
DD
0.5V) to (V
DD
-10V)
DC Current into any Input or Output
. . . . . . . . . . . . . . . . . . . . . .
20mA
Maximum Junction Temperature . . . . . . . . . . . . . . . . . . . . . . .175
o
C
Maximum Storage Temperature Range . . . . . . . . . . -65
o
C to 150
o
C
Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . .300
o
C
Operating Conditions
Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0
o
C to 70
o
C
CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress only rating and operation of the
device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
Electrical Specifications
0
o
C
T
A
70
o
C, V
DD
= 5V
10%
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
UNITS
Frequency Detect Bandwidth
(1.5 + 2Hz)
2.3
3.5
% of f
O
Amplitude for Detection
Each Tone
-32
(Note 3)
-
-2
dBm Referenced to 600
Minimum Acceptable Twist
-8
-
+4
dB
60Hz Tolerance
-
-
0.8
V
RMS
Dial Tone Tolerance
"Precise" Dial Tone
-
-
0
dB Referenced to Lower
Amplitude Tone
Talk Off
MITEL Tape #CM7291
-
2
-
Hits
Digital Outputs (except XOUT)
"0" Level, 400
A Load
0
-
0.5
V
"1" Level, 200
A Load
V
DD
-0.5
-
V
DD
V
Digital Inputs
"0" Level
0
-
0.3V
DD
V
"1" Level
0.7V
DD
-
V
DD
V
Supply Current
T
A
= 25
o
C
-
10
20
mA
Noise Tolerance
MITEL Tape #CM7291
(Note 2)
-
-
-12
dB Referenced to Lowest
Amplitude Tone
Input Impedance
V
DD
V
IN
(V
DD
-10)
100k
//15pF
300k
-
NOTES:
1. Unused inputs must be connected to V
DD
or V
SS
as appropriate.
2. Bandwidth limited (3kHz) Gaussian noise.
3. Lower minimum available, please contact sales office.
(-32dBm = 19.45mV
RMS
, -2dBm = 0.615mV
RMS
)
Twist
High Tone
Low Tone
----------------------------
=
CD22204
69
Functional Block Diagram
System Functions
Analog In
The Analog In pin accepts the analog input. It is internally
biased so that the input signal may be either AC or DC cou-
pled, as long as it does not exceed the positive supply volt-
age. Proper input coupling is illustrated below.
FIGURE 1. ANALOG IN
The CD22204 is designed to accept sinusoidal input wave-
forms, but will operate satisfactorily with any input that has
the correct fundamental frequency with harmonics that are
at least 20dB below the fundamental.
Crystal Oscillator
The CD22204 contains an on-board inverter with sufficient
gain to provide oscillation when connected to a low cost tele-
vision "color-burst" (3.579545MHz) crystal. The crystal oscil-
lator is enabled by tying XEN high. The crystal is connected
between XIN and XOUT. A 1M
resistor is also connected
between these pins in this mode. ATB is a clock frequency
output. Other CD22204 devices may use the same fre-
quency reference by tying their ATB pins to the ATB output of
a crystal connected device. XIN and XEN of the auxiliary
devices must then be tied high and low, respectively. Up to
ten devices may be run from a single crystal connected
CD22204 as shown in Figure 2.
8
60Hz
REJECT
CLOCK
GENERATOR
CHIP CLOCKS
PRE EMP
POWER REGULATOR
4
8
V
DD
V
SS
VOLTAGE
REF
697
770
852
941
1209
1336
1477
1633
BAND
SPLIT
FILTERS
ZERO
CROSSING
DETECTORS
BANDPASS
FILTERS
AMPLITUDE
DETECTORS
OUTPUT
DECODER
OUTPUT
REGISTER
TIMING
CIRCUITRY
DATA STROBE
12
2
1
14
13
3
DATA CLEAR
DV
D1
D2
D4
D8
EN
ANALOG
IN
PREPROCESSOR
7
BS1
BS2
10
9
11
6
ATB
XEN
XIN
XOUT
1M
NOTE: Pin numbers are for plastic DIP.
7
V
SS
V
DD
10pF
>100k
(ON CHIP)
270k
33k
ANALOG
IN
1500pF
OPTIONAL
HIGH FREQUENCY
NOISE FILTER
(f
C
= 3.9kHz)
AUDIO
INPUT
(+4dBm OR
1.22V
RMS
0.01
F
CD22204E
MAXIMUM)
CD22204
70
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.
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
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.
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.
FIGURE 4. FILTER FOR USE IN EXTREME HIGH FREQUENCY
INPUT NOISE ENVIRONMENT
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
XEN
XEN
CD22204
10
9
6
11
ATB
XIN
3.579545MHz
V
DD
XOUT
1M
10
11
6
XIN CONNECTED TO V
DD
UP TO 10 DEVICES
CD22204
COL 0
1209Hz
COL 1
1336Hz
COL 2
1477Hz
COL 3
1633Hz
ROW 0
697Hz
ROW 1
770Hz
ROW 2
852Hz
ROW 3
941Hz
NOTE: Column 3 is for special applications and is not normally used
in telephone dialing.
1
2
3
A
4
5
6
B
7
8
9
C
*
0
#
D
V
DD
V
SS
CMOS
DIGITAL
CIRCUITRY
DIGITAL
OUTPUT
DIGITAL
INPUT
CD22204
33k
0.0015
F
270k
ANALOG
IN
NOISY
SIGNAL
CD22204
71
All Intersil semiconductor products are manufactured, assembled and tested under ISO9000 quality systems certification.
Intersil semiconductor products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design and/or specifications at any time with-
out notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and
reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
For information regarding Intersil Corporation and its products, see web site http://www.intersil.com
Sales Office Headquarters
NORTH AMERICA
Intersil Corporation
P. O. Box 883, Mail Stop 53-204
Melbourne, FL 32902
TEL: (407) 724-7000
FAX: (407) 724-7240
EUROPE
Intersil SA
Mercure Center
100, Rue de la Fusee
1130 Brussels, Belgium
TEL: (32) 2.724.2111
FAX: (32) 2.724.22.05
ASIA
Intersil (Taiwan) Ltd.
7F-6, No. 101 Fu Hsing North Road
Taipei, Taiwan
Republic of China
TEL: (886) 2 2716 9310
FAX: (886) 2 2715 3029
Noise will also be reduced by placing a grounded trace
around XIN and XOUT pins on the circuit board layout when
using a crystal. It is important to note that XOUT is not
intended to drive an additional device. XIN may be driven
externally; in this case, leave XOUT floating.
Timing Waveforms
FIGURE 5.
t
ON
t
OFF
PAUSE
ANALOG
INPUT
D1, D2
D4, D8
TONE BURST 1
TONE BURST 2
t
D
t
R
t
SU
t
H
DV
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
Tone Time
For Detection
t
ON
40
-
-
ms
For Rejection
t
ON
-
-
20
ms
Pause Time
For Detection
t
OFF
40
-
-
ms
For Rejection
t
OFF
-
-
20
ms
Detect Time
t
D
25
-
46
ms
Release Time
t
R
35
50
ms
Data Setup Time
t
SU
7
-
-
s
Data Hold Time
t
H
4.2
-
5
ms
Output Enable Time
C
L
= 50pF, R
L
= 1k
-
-
200
300
ns
Output Disable Time
C
L
= 35pF, R
L
= 500
-
-
150
200
ns
Output Rise Time
C
L
= 50pF
-
-
200
300
ns
Output Fall Time
C
L
= 50pF
-
-
160
250
ns
CD22204
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