Datasheet CD22204M, CD22204E Datasheet (Harris Semiconductor)

4-1

SEMICONDUCTOR

Description

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.

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

Ordering Information

PART

NUMBER

TEMP .

RANGE (oC) PACKAGE PKG. NO.

CD22204E 0 to 70 14 Ld PDIP E14.3
CD22204M 0 to 70 24 Ld Plastic SOIC M24.3

January 1997

Pinouts

CD22204 (PDIP)

TOP VIEW

CD22204 (SOIC)

TOP VIEW

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

1
2
3
4
5
6
7
8

9
10
11
12

D2
D1

EN
NC
NC

V

DD

NC
NC
NC
NC

XEN

AIN

16

17

18

19

20

21

22

23

24

15
14
13

D4

NC
NC
DV
NC

NC

NC
XOUT
V

SS

D8

ATB

XIN

Functional Diagram

HIGH B/P

FILTERS

LOW B/P
FILTERS

VOLTAGE

REG./REF.

CLOCK

GENERATOR

CHIP
CLOCKS

ATB

XEN

11

6

10

9

48

DETECTORS AND SIGNAL-

PROCESSING CIRCUITS

5

12

2

1

14

13

3

DV

D1

D4

D8

EN

XIN

XOUT

D2

V

SS

V

DD

PREPROCESSOR/

BANDSPLIT FILTER

ANALOG IN

7

NC

NOTE: Pin numbers are for PDIP.

CD22204

5V Low Power Subscriber

DTMF Receiver

CAUTION: These devices are sensitive to electrostatic discharge. Users should follow proper IC Handling Procedures.
Copyright

© Harris Corporation 1997

File Number 1696.3

4-2

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 Junction Temperature (Plastic) . . . . . . . . . . . . . . . . 150oC

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.

Electrical Specifications 0

o

C ≤ TA≤ 70oC, VDD = 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 600Ω

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, 400µA Load 0 - 0.5 V

“1” Level, 200µA Load VDD -0.5 - V

DD

V
Digital Inputs “0” Level 0 - 0.3V

DD

V

“1” Level 0.7V

DD

-VDDV
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 = 19.45mV

RMS

, -2dBm = 0.615mV

RMS

)

Tw ist

High Tone

Low To ne

--------------------------- -=

4-3

CD22204

Functional Block Diagram

÷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.

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.

FIGURE 1. ANALOG IN

7

V

SS

V

DD

10pF

>100kΩ

(ON CHIP)

270kΩ

33kΩ

ANALOG

IN

1500pF

OPTIONAL
HIGH FREQUENCY
NOISE FILTER
(f

C

= 3.9kHz)

AUDIO

INPUT

(+4dBm OR

1.22V

RMS

0.01µF

CD22204E

MAXIMUM)

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.

4-4

CD22204

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.

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 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.

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

10001
20010
30011
40100
50101
60110
70111
81000
91001
01010
*1011
#1100
A1101

B1110
C1111
D0000

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

33kΩ

0.0015µF

270kΩ

ANALOG

IN

NOISY

SIGNAL

4-5

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Harris Semiconductor products are sold by description only. Harris Semiconductor 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 Harris is
believed to be accurate and reliable. However, no responsibility is assumed by Harris 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 Harris or its subsidiaries.

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SEMICONDUCTOR

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

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--µs

Data Hold Time t

H

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