75t204 ETC-unknow, 75t204 Datasheet

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75t204

Manufacturer Part Number
75t204
Description
Low-power Subscriber Dtmf Receiver
Manufacturer
ETC-unknow
Datasheet

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DESCRIPTION
The 75T204 is a complete Dual-Tone Multifrequency
(DTMF) receiver that detects 16 standard digits. No
front-end pre-filtering is needed. The only external
components required are an inexpensive 3.58-MHz
television “colorburst” crystal for frequency reference
and a bias resistor. An Alternate Time Base (ATB)
is provided to permit operation of up to 10 75T204's
from a single crystal. The 75T204 employs state-of-
the-art
resulting in approximately 40 poles of filtering, and
digital circuitry on the same CMOS chip. The analog
input signal is pre-processed by 60-Hz reject and
band split filters and then zero-cross detected to
provide AGC.
individual tones.
measure the tone and pause durations
1Mz
ANALOG
XOUT
A T B
XEN
XIN
"switched-capacitor"
REJECT
PRE-PROCESSOR
60 Hz
Eight bandpass filters detect the
Digital processing is used to
PREEMP
÷ 8
filter
FILTERS
BAND
SPLIT
BS1
BS2
GENERATOR
technology,
CLOCK
DETECTORS
CROSSING
(continued)
VP
ZERO
BLOCK DIAGRAM
POWER REGULATOR
GND
CHIP CLOCKS
BANDPASS FILTERS
1209
1336
1477
1633
697
770
852
941
FEATURES
Intended for applications with less
requirements than the 75T202/75T203
14-pin plastic DIP or 16-pin SO package for
high system density
NO front-end band-splitting filters required
Single low-tolerance 5-volt supply
Detects all 16 standard DTMF digits.
Uses an inexpensive 3.579545-MHz crystal
Excellent speech immunity
Output in 4-bit hexadecimal code
Three-state outputs for microprocessor
interface
VOLTAGE
5V Low-Power Subscriber
REF
DETECTORS
AMPLITUDE
DECODER
OUTPUT
CIRCUITRY
TIMING
DATA STROBE
DTMF Receiver
DATA CLEAR
DV
REGISTER
OUTPUT
75T204
April 2000
DV
D1
D2
D4
D8
EN

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75t204 Summary of contents

Page 1

... The only external components required are an inexpensive 3.58-MHz television “colorburst” crystal for frequency reference and a bias resistor. An Alternate Time Base (ATB) is provided to permit operation 75T204's from a single crystal. The 75T204 employs state-of- the-art "switched-capacitor" resulting in approximately 40 poles of filtering, and digital circuitry on the same CMOS chip ...

Page 2

... XIN and XOUT 10% resistor is also connected between these pins. In this mode, ATB is a clock frequency output. Other 75T204’s (or 75T202's) may use the same frequency reference by tying their ATB pins to the ATB of a crystal connected device. XIN and XEN of the auxiliary devices must then be tied high and low respectively ...

Page 3

... V P VIN < Analog >100 k GND FIGURE 1: Input Coupling XIN 10 75T204 ATB 11 XIN Connected 75T204 Devices FIGURE 2: Crystal Connections 5V Low-Power Subscriber DTMF Receiver V P VIN > VP 0.01 µF 7 Analog >100 k GND VP XOUT 9 XEN 6 XEN 6 3 75T204 ...

Page 4

... Low-Power Subscriber DTMF Receiver DTMF DIALING MATRIX See Figure 3. Please note that column 3 is for special applications and is not normally used in telephone dialing. Analog Tone burst 1 Input tD D1, D2, D4 Col 0 Col 1 Col Row Row Row Row 3 ...

Page 5

... DETECTION FREQUENCY Low Group f 0 Row 0 = 697 Hz Row 1 = 770 Hz Row 2 = 852 Hz Row 3 = 941 Hz 75T204 TIMING (Refer to Figure 4.) PARAMETER t Tone Time ON t Pause Time OFF t Detect Time D t Release Time R t Data Setup Time SU t Data Hold Time H Output Enable Time Output Disable Time ...

Page 6

... Low-Power Subscriber DTMF Receiver APPLICATION INFORMATION The 75T204 will tolerate total input RMS noise up to 12dB below the lowest amplitude tone. telephone applications, the combination of the high frequency attenuation of the telephone line and internal band-limiting make special circuitry at the input to the 75T204 unnecessary. However, noise ...

Page 7

... MITEL tape #CM 7290 V ³V ³V - 100K ||15pF 7 5V Low-Power Subscriber DTMF Receiver All 75T204 unused inputs must be RATING +7V - +85 C Ambient - +150 C 65mW (V + 0.5V) to -0. .5V 10V ±1.0mA 300 C MIN ...

Page 8

... Low-Power Subscriber DTMF Receiver MECHANICAL SPECIFICATIONS 14-Pin DIP 16-Pin SOL 8 ...

Page 9

... ANALOG IN 8 ORDER NUMBER 75T204-IP 75T204-IL 9 75T204 DTMF Receiver CAUTION: Use handling procedures necessary for a static sensitive component N 75T204 N/C ATB 5 12 XIN N XOUT XEN 7 10 GND 8 9 16-Pin SOL PACKAGING MARK 75T204-IP 75T204-IL 04/24/00- rev. C ...

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