INTERSIL CD22204E

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SIL
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1-888-
CD22204
TM
November 2002
FN1696.5
5V Low Power Subscriber DTMF Receiver
Features
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.
• No Front End Band Splitting Filters Required
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 threestate enabled to facilitate bus oriented architectures.
• Excellent Latch-Up Immunity
Part Number Information
PART
NUMBER
TEMP.
RANGE (oC)
CD22204E
0 to 70
PACKAGE
14 Ld PDIP
PKG. NO.
• 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
Pinouts
CD22204 (PDIP)
TOP VIEW
D2 1
14 D4
D1 2
13 D8
EN 3
12 DV
VDD 4
11 ATB
NC 5
10 XIN
XEN 6
ANALOG 7
IN
E14.3
9 XOUT
8 VSS
Functional Diagram
FILTERS
DV
2
FILTERS
ATB
6
CHIP
CLOCKS
XEN
CLOCK
9
XOUT
GENERATOR
XIN
PROCESSING CIRCUITS
D1
HIGH B/P
11
10
12
DETECTORS AND SIGNAL-
ANALOG IN
NC
LOW B/P
BANDSPLIT FILTER
7
PREPROCESSOR/
5
1
D2
14
D4
13
D8
3
EN
VOLTAGE
REG./REF.
4
VDD
8
VSS
NOTE: Pin numbers are for PDIP.
1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 321-724-7143 | Intersil (and design) is a registered trademark of Intersil Americas Inc.
Copyright © Intersil Americas Inc. 2002. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
CD22204
Absolute Maximum Ratings (Note 1)
Thermal Information
DC Supply Voltage (VDD) (Referenced to VSS Terminal) . . . . . . .7V
Power Dissipation
TA = 25oC (Derate above TA = 25oC at 6.25mW/oC . . . . . . .65mW
Input Voltage Range
All Inputs Except Analog In . . . . . . . . . . . . . . (VDD 0.5V) to -0.5V
Analog in Voltage Range . . . . . . . . . . . . . (VDD 0.5V) to (VDD -10V)
DC Current into any Input or Output . . . . . . . . . . . . . . . . . . . . . . ±20mA
Maximum Junction Temperature . . . . . . . . . . . . . . . . . . . . . . .175oC
Maximum Storage Temperature Range . . . . . . . . . -65oC to 150oC
Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . . 300oC
Operating Conditions
Temperature Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . 0oC to 70oC
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.
0oC ≤ TA ≤ 70oC, VDD = 5V ±10%.
Electrical Specifications
PARAMETER
TEST CONDITIONS
Frequency Detect Bandwidth
Amplitude for Detection
Each Tone
Minimum Acceptable Twist
MIN
TYP
MAX
UNITS
±(1.5 + 2Hz)
±2.3
±3.5
-32
(Note 3)
-
-2
dBm Referenced to 600Ω
-8
-
+4
dB
-
-
0.8
VRMS
% of fO
High Tone
Twist = ---------------------------Low Tone
60Hz Tolerance
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, 400µA Load
0
-
0.5
V
“1” Level, 200µA Load
VDD -0.5
-
VDD
V
“0” Level
0
-
0.3VDD
V
“1” Level
0.7VDD
-
VDD
V
Digital Inputs
Supply Current
TA = 25oC
-
10
20
mA
Noise Tolerance
Mitel Tape #CM7291
(Note 2)
-
-
-12
dB Referenced to Lowest
Amplitude Tone
Input Impedance
VDD ≥ VIN ≥ (VDD -10)
100kΩ//15pF
300kΩ
-
NOTES:
1. Unused inputs must be connected to VDD or VSS as appropriate.
2. Bandwidth limited (3kHz) Gaussian noise.
3. Lower minimum available, please contact sales office.
(-32dBm = 19.45mVRMS, -2dBm = 0.615mVRMS)
2
CD22204
Functional Block Diagram
BANDPASS
FILTERS
ANALOG
IN
BAND
SPLIT
FILTERS
PREPROCESSOR
60Hz
REJECT
7
PRE EMP
ZERO
CROSSING
DETECTORS
BS1
697
AMPLITUDE
DETECTORS
770
852
941
BS2
TIMING
CIRCUITRY
1209
1336
ATB 11
1477
XEN
DV
12
6
1633
DATA STROBE
÷8
10
CLOCK
GENERATOR
CHIP CLOCKS
XIN
2 D1
1M
1 D2
OUTPUT
DECODER
XOUT
9
POWER REGULATOR
OUTPUT
REGISTER
14 D4
VOLTAGE
REF
13 D8
DATA CLEAR
4
8
VDD
VSS
3 EN
NOTE: Pin numbers are for plastic DIP.
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
coupled, as long as it does not exceed the positive supply
voltage. Proper input coupling is illustrated below.
CD22204E
0.01µF
AUDIO
INPUT
(+4dBm OR
1.22VRMS
MAXIMUM)
VDD
270kΩ
7
1500pF
33kΩ
10pF
(ON CHIP)
ANALOG
IN
>100kΩ
VSS
OPTIONAL
HIGH FREQUENCY
NOISE FILTER
(fC = 3.9kHz)
FIGURE 1. ANALOG IN
3
The CD22204 is designed to accept sinusoidal input
waveforms, 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
television “color-burst” (3.579545MHz) crystal. The crystal
oscillator is enabled by tying XEN high. The crystal is
connected between XIN and XOUT. A 1MΩ resistor is also
connected between these pins in this mode. ATB is a clock
frequency output. Other CD22204 devices may use the
same frequency 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.
CD22204
DTMF Dialing Matrix
3.579545MHz
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
1M
10
ATB
VDD
XOUT
XIN
9
6
CD22204
11
XEN
XIN CONNECTED TO VDD
10
11
NOTE: Column 3 is for special applications and is not normally used
in telephone dialing.
XEN
CD22204
6
UP TO 10 DEVICES
Digital Inputs and Outputs
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
disabled 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.
All digital inputs and outputs of the DTMF receivers are
represented 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
CMOS
DIGITAL
CIRCUITRY
DIGITAL
INPUT
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
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.
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.
DIGITAL
OUTPUT
NOISY
SIGNAL
270kΩ
0.0015µF
ANALOG
IN
CD22204
33kΩ
N/C Pin
This pin has no internal connection and should be left floating.
4
FIGURE 4. FILTER FOR USE IN EXTREME HIGH
FREQUENCY INPUT NOISE ENVIRONMENT
CD22204
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
tON
TONE BURST 1
tOFF
PAUSE
ANALOG
INPUT
TONE BURST 2
tR
tD
D1, D2
D4, D8
tSU
tH
DV
FIGURE 5.
TABLE 2.
PARAMETER
SYMBOL
MIN
TYP
MAX
UNITS
For Detection
tON
40
-
-
ms
For Rejection
tON
-
-
20
ms
For Detection
tOFF
40
-
-
ms
For Rejection
tOFF
-
-
20
ms
Detect Time
tD
25
-
46
ms
Release Time
tR
35
50
ms
Data Setup Time
tSU
7
-
-
µs
Data Hold Time
tH
4.2
-
5
ms
Output Enable Time
CL = 50pF, RL = 1kΩ
-
-
200
300
ns
Output Disable Time
CL = 35pF, RL = 500Ω
-
-
150
200
ns
Output Rise Time
CL = 50pF
-
-
200
300
ns
Output Fall Time
CL = 50pF
-
-
160
250
ns
Tone Time
Pause Time
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 without 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 www.intersil.com
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