Intersil CD22202 5v low power dtmf receiver Datasheet

DTMF Receivers/Generators
CD22202, CD22203
5V Low Power DTMF Receiver
January 1997
Features
Description
• Central Office Quality
The CD22202 and CD22203 complete dual-tone multiple
frequency (DTMF) receivers detect 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 clock output of a crystal connected CD22202/CD22203 receiver to drive the time bases
of additional receivers. This is a monolithic integrated circuit
fabricated with low-power, complementary symmetry CMOS
processing. It only requires a single low tolerance power
supply.
• No Front End Band Splitting Filters Required
• Single, Low Tolerance, 5V Supply
• Detects Either 12 or 16 Standard DTMF Digits
• Uses Inexpensive 3.579545MHz Crystal for Reference
• Excellent Speech Immunity
• Output in Either 4-Bit Hexadecimal Code or Binary
Coded 2-of-8
• Synchronous or Handshake Interface
The CD22202 and CD22203 employ state-of-the-art circuit
technology to combine the digital and analog functions on
the same CMOS chip using a standard digital semiconductor
process. The analog input is preprocessed by 60Hz reject
and band splitting filters and then hard limited to provide
AGC. Eight Bandpass filters detect the individual tones. The
digital post processor times the tone durations and provides
the correctly coded digital outputs. Outputs interface directly
to standard CMOS circuitry and are three-state enabled to
facilitate bus oriented architectures.
• Three-State Outputs
• Excellent Latch-Up Immunity
Ordering Information
PART
NUMBER
TEMP.
RANGE (oC)
PACKAGE
PKG. NO.
CD22202E
0 to 70
18 Ld PDIP
E18.3
CD22203E
0 to 70
18 Ld PDIP
E18.3
Functional Diagram
CD22202, CD22203
(PDIP)
TOP VIEW
HEX/B28
1
2
18 D2
ANALOG IN
9
17 D4
EN
3
16 D8
IN1633
4
15 CLRDV
VDD
5
14 DV
ED (203 ONLY),
NC (202)
VSS
6
13 ATB
7
12 XIN
XEN
8
11 XOUT
ANALOG IN
9
10 VSS
LOW B/P
FILTERS
CLRDV
14
HIGH B/P
FILTERS
13
ATB
XEN
8
CHIP
CLOCKS
12
11
CLOCK
GENERATOR
XIN
XOUT
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
4-245
ED-203
NC-202
15
DETECTORS AND SIGNALPROCESSING CIRCUITS
D1
6
PREPROCESSOR/
BANDSPLIT FILTER
Pinout
DV
2
HEX/B28
1
D1
18
D2
17
D4
16
D8
3
VOLTAGE
REG./REF.
5
VDD
10
VSS
EN
7
4
INI633
File Number
1695.3
CD22202, CD22203
Absolute Maximum Ratings
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 Junction Temperature (Plastic) . . . . . . . . . . . . . . . . 150oC
Maximum Storage Temperature Range . . . . . . . . . . -65oC to 150oC
Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . . 300oC
Operating Conditions
Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . . . . 0oC to 70oC
NOTE: Unused inputs must be connected to VDD or VSS as appropriate.
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
PARAMETER
0oC ≤ TA ≤ +70oC, VDD = 5V ±10%
TEST CONDITIONS
Frequency Detect Bandwidth
MIN
TYP
MAX
±(1.5 + 2Hz)
±2.3
±3.5
UNITS
% of fO
Amplitude for Detection
Each Tone
-32
-
-2
Minimum Acceptable Twist
High To ne
Tw ist = ---------------------------Low To ne
-10
-
+10
dB
-
-
0.8
VRMS
60Hz Tolerance
dBm Referenced to 600Ω
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
16
mA
Noise Tolerance
MITEL Tape #CM7291
(Note 1)
-
-
-12
dB Referenced to Lowest
Amplitude Tone
Input Impedance
VDD ≥ VIN ≥ (VDD -10)
100kΩ//15pF
300kΩ
-
NOTE:
1. Bandwidth limited (3kHz) Gaussian noise.
4-246
CD22202, CD22203
Functional Block Diagram
CD22202
CD22203
BANDPASS
FILTERS
ANALOG
IN
BAND
SPLIT
FILTERS
PREPROCESSOR
60Hz
REJECT
9
PRE EMP
697
ZERO
CROSSING
DETECTORS
770
BS1
AMPLITUDE
DETECTORS
EARLY
DETECT
OUTPUT
852
6
941
BS2
CLRDV
TIMING
CIRCUITRY
1209
15
1336
CLR
ATB 13
1477
8
XEN
DV
STROBE
1633
DV
F.F
DV
14
DATA STROBE
÷8
12
CLOCK
GENERATOR
H/B28
CHIP CLOCKS
2
XIN
1 D1
1MΩ
18 D2
OUTPUT
DECODER
XOUT
11
OUTPUT
REGISTER
17 D4
VOLTAGE
REF
POWER REGULATOR
16 D8
DATA CLEAR
5
10
7
VDD
VSS
VSS
IN1633
3 EN
4
NOTE: Pin 6: Early detect output on CD22203 only.
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.
The CD22202 and CD22203 are 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
CD22202, CD22203
VDD
0.01µF
AUDIO
INPUT
(+4dBm
MAXIMUM)
270kΩ
9
1500pF
33kΩ
10pF
(ON CHIP)
ANALOG
IN
>100kΩ
VSS
OPTIONAL
HIGH FREQUENCY
NOISE FILTER
(fC = 3.9kHz)
The CD22202 and CD22203 contain 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 CD22202 and CD22203
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 CD22202 and CD22203 as shown
in Figure 2.
FIGURE 1. ANALOG IN
4-247
CD22202, CD22203
DV remains high until a valid pause occurs or CLRDV is
raised high, whichever is sooner. This handshake can save
microprocessor time.
3.579545MHz
1M
12
ATB
11
8
CD22202/22203
13
DTMF Dialing Matrix
VDD
XOUT
XIN
12
XEN
CD22202/22203
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
XEN
XIN CONNECTED TO VDD
13
COL 0
1209Hz
8
UP TO 10 DEVICES
NOTE: Column 3 is for special applications and is not normally used
in telephone dialing.
FIGURE 2. CRYSTAL OSCILLATOR
HEX/B28
This pin selects the format of the digital output code. When
HEX/B28 is tied high, the output is hexadecimal. When tied
low, the output is binary coded 2-of-8. The following table
describes the two output codes.
TABLE 1. OUTPUT CODES
HEXADECIMAL
IN1633
When tied high, this pin inhibits detection of tone pairs containing the 1633Hz component. For detection of all 16 standard digits, IN1633 must be tied low.
N/C Pin
BINARY CODED 2-OF-8
DIGIT
D8
D4
D2
D1
D8
D4
D2
D1
1
0
0
0
1
0
0
0
0
2
0
0
1
0
0
0
0
1
3
0
0
1
1
0
0
1
0
4
0
1
0
0
0
1
0
0
5
0
1
0
1
0
1
0
1
6
0
1
1
0
0
1
1
0
7
0
1
1
1
1
0
0
0
8
1
0
0
0
1
0
0
1
9
1
0
0
1
1
0
1
0
0
1
0
1
0
1
1
0
1
*
1
0
1
1
1
1
0
0
#
1
1
0
0
1
1
1
0
A
1
1
0
1
0
0
1
1
B
1
1
1
0
0
1
1
1
C
1
1
1
1
1
0
1
1
D
0
0
0
0
1
1
1
1
This pin has no internal connection and should be left floating.
Digital Inputs and Outputs
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
DIGITAL
OUTPUT
VSS
FIGURE 3. DIGITAL INPUTS AND OUTPUTS
ED
Input Filter
This pin, on the CD22203 only, indicates the presence of frequencies which are likely to be DTMF digits, but have not yet
been verified by a DV signal. It is comparable to a “buttondown” output, and it is useful as an EARLY DETECT signal to
interrupt a microprocessor for digit storage and validation.
DV and CLRDV
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.
The CD22202 and CD22203 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
4-248
CD22202, CD22203
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
ANALOG
IN
270kΩ
CD22202
CD22203
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
tOFF
PAUSE
TONE BURST 2
tR
tD
D1, D2
D4, D8
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
DV Clear Time
tCL
-
160
250
ns
CLRDV Pulse Width
tPW
200
-
-
ns
ED Detect Time
tED
7
-
22
ms
ED Release Time
tER
2
-
18
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
FIGURE 4. FILTER FOR USE IN EXTREME HIGH FREQUENCY
INPUT NOISE ENVIRONMENT
ANALOG
INPUT
SYMBOL
33kΩ
0.0015µF
TONE BURST 1
PARAMETER
tSU
tH
tCL
DV
tPW
CLRDV
tED
tER
ED
(NOTE)
NOTE: Early Detect output is available only on the CD22203.
FIGURE 5.
Guard Time
Whenever the DTMF receiver is continually monitoring a
voice channel containing distorted or musical voices or
tones, additional guard time may be added in order to
prevent false decoding. This may be done in software by
verifying that both ED and DV are present simultaneously for
about 55ms. An appropriate guard time should be selected
to balance the fastest expected dialing speed against the
rejection of distorted or musical voices or tones (most
autodialers operate in the 65ms to 75ms range although a
few generate 50ms tones). A hardware guard time circuit is
shown in Figure 6. R3 and R4 should keep the voice
amplitude as low as practical, while R2 and R5 adjust
detection speed.
4-249
CD22202, CD22203
+5V
R2
10µF
≈ 240K
D1
(55ms)
HEX/B28
EN
1
18
2
17
3
16
4
15
5
14
6
13
7
12
8
11
IN1633
VDD
IN4148
ED
VSS
C2
0.15µF
XEN
ANALOG IN
9
10
D2
D4
D8
CLRDV
DV
ATB
XIN
XOUT
3.58
MHz
VSS
R1
1M
R5
1.8M
R6
100K
R3
≈ 390K
R4
33K
AUDIO
IN
C1
4700pF
D8 D4 D2 D1
HEX DATA OUT
ENABLE
INPUT 1/3 CD74HC04
DV
OUT
(BUFFERS OPTIONAL)
FIGURE 6. CD22203 DTMF RECEIVER WITH GUARD TIME CIRCUIT TO PROVIDE EXCEPTIONAL TALK-OFF PERFORMANCE
Operating and Handling Considerations
Handling
Input Signals
All inputs and outputs of CMOS devices have a network for
electrostatic protection during handling. Recommended handling practices for CMOS devices are described in
ICAN-6525 “Guide to Better Handling and Operation of
CMOS Integrated Circuits”.
To prevent damage to the input protection circuit, input signals should never be greater than VDD nor less than VSS.
Input currents must not exceed 20mA even when the power
supply is off.
Operating
A connection must be provided at every input terminal. All
unused input terminals must be connected to either VDD or
VSS, whichever is appropriate.
Operating Voltage
During operation near the maximum supply voltage limit,
care should be taken to avoid or suppress power supply
turn-on and turnoff transients, power supply ripple, or ground
noise; any of these conditions must not cause VDD - VSS to
exceed the absolute maximum rating.
Unused Inputs
Output Short Circuits
Shorting of outputs to VDD or VSS may damage CMOS
devices by exceeding the maximum device dissipation.
All Intersil semiconductor products are manufactured, assembled and tested under ISO9000 quality systems certification.
Intersil 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 http://www.intersil.com
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