75T204_ds (174772 байта)

75T204_ds (174772 байта)
75T204
5V Low-Power Subscriber
DTMF Receiver
April 2000
DESCRIPTION
FEATURES
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-ofthe-art
"switched-capacitor"
filter
technology,
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. Eight bandpass filters detect the
individual tones.
Digital processing is used to
measure the tone and pause durations
•
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
(continued)
BLOCK DIAGRAM
BANDPASS FILTERS
697
BAND
SPLIT
FILTERS
PRE-PROCESSOR
ANALOG
60 Hz
REJECT
PREEMP
ZERO
CROSSING
DETECTORS
BS1
AMPLITUDE
DETECTORS
770
852
941
BS2
TIMING
CIRCUITRY
1209
1336
ATB
DV
1477
DV
XEN
XIN
DATA STROBE
1633
÷8
CLOCK
GENERATOR
CHIP CLOCKS
D1
1Mz
XOUT
D2
OUTPUT
DECODER
OUTPUT
REGISTER
D4
POWER REGULATOR
VOLTAGE
REF
D8
DATA CLEAR
EN
VP
GND
75T204
5V Low-Power Subscriber
DTMF Receiver
DESCRIPTION (continued)
DV
and to provide output timing and decoding. The
outputs interface directly to standard CMOS circuitry
and are three-state enabled to facilitate bus-oriented
architectures.
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.
ANALOG IN
N/C PINS
This pin accepts the analog input. It is internally
biased so that the input signal may be AC coupled.
The input may be DC coupled as long as it does not
exceed the positive supply. Proper input coupling is
illustrated in Figure 1.
These pins have no internal connection and may be
left floating.
Output Code
The 75T204 is designed to accept sinusoidal input
wave forms but will operate satisfactorily with any
input that has the correct fundamental frequency
with harmonics less then -20 dB below the
fundamental.
CRYSTAL OSCILLATOR
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
The 75T204 contains an onboard inverter with
sufficient gain to provide oscillation when connected
to a low-cost television “colorburst” crystal. The
crystal oscillator is enabled by tying XEN high. The
crystal is connected between XIN and XOUT. A
1 Mz 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. Ten devices may run off a single
crystal-connected 75T204 (or 75T202) as shown in
Figure 2.
B
1
1
1
0
C
1
1
1
1
OUTPUTS D1, D2, D4, D8 and EN
D
0
0
0
0
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 (DV is high) and they are then cleared
when a valid pause is timed. The hexadecimal
codes are described in Table 1.
TABLE 1: Output Codes
2
75T204
5V Low-Power Subscriber
DTMF Receiver
VP
VP
VIN > VP
VIN < VP
(On Chip)
(On Chip)
7
Analog In
0.01 µF
7
10 pF
Analog In
10 pF
>100 k Ω
>100 k Ω
GND
GND
FIGURE 1: Input Coupling
VP
XIN
XOUT
10
ATB
9
75T204
6
XEN
11
XIN Connected to VP
10
75T204
6
XEN
11
Up to 10 Devices
FIGURE 2: Crystal Connections
3
75T204
5V 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.
Col 0
Col 1
Col 2
Col 3
Row 0
1
2
3
A
Row 1
4
5
6
B
Row 2
7
8
9
C
Row 3
*
0
#
D
FIGURE 3: DTMF Dialing Matrix
Analog
Input
ton
toff
Tone burst 1
Pause
tR
tD
D1, D2,
D4, D8
tS
tH
DV
FIGURE 4: Timing Diagram
4
Tone burst 2
75T204
5V Low-Power Subscriber
DTMF Receiver
DETECTION FREQUENCY
Low Group f0
High Group f0
Row 0 = 697 Hz
Column 0 = 1209 Hz
Row 1 = 770 Hz
Column 1 = 1336 Hz
Row 2 = 852 Hz
Column 2 = 1477 Hz
Row 3 = 941 Hz
Column 3 = 1633 Hz
75T204 TIMING (Refer to Figure 4.)
PARAMETER
CONDITIONS
tON
tOFF
Tone Time
Pause Time
MIN
NOM
MAX
UNITS
for detection
40
-
-
ms
for rejection
-
-
20
ms
for detection
40
-
-
ms
for rejection
-
-
20
ms
tD
Detect Time
25
-
46
ms
tR
Release Time
35
-
50
ms
tSU
Data Setup Time
7
-
-
µs
tH
Data Hold Time
4.2
-
5.0
ms
Output Enable Time
CL = 50pF, RL = 1k½
-
-
200
ns
Output Disable Time
CL = 35pF, RL = 500½
-
-
200
ns
Output Rise Time
CL = 50pF
-
-
200
ns
Output Fall Time
CL = 50pF
-
-
200
ns
5
75T204
5V Low-Power Subscriber
DTMF Receiver
APPLICATION INFORMATION
excessive noise is present above 28kHz, the simple
RC filter shown in Figure 5 may be employed to
band limit the incoming signal.
The 75T204 will tolerate total input RMS noise up to
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 the 75T204 unnecessary. However, noise
near the 56kHz internal sampling frequency will be
aliased (folded back) into the audio spectrum, so if
Noise will also be reduced by placing a grounded
trace around the 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.
2.4 k = 5%
ANALOG IN
NOISY
SIGNAL
0.01 mF = 20%
FIGURE 5: RC Filter
6
75T204
75T204
5V Low-Power Subscriber
DTMF Receiver
ELECTRICAL SPECIFICATIONS
ABSOLUTE MAXIMUM RATINGS
(Operation above absolute maximum ratings may damage the device.
connected to VP or GND, as appropriate.)
All 75T204 unused inputs must be
PARAMETER
RATING
DC Supply Voltage - VP
+7V
Operating Temperature
-40°C to +85°C Ambient
Storage Temperature
-65°C to +150°C
Power Dissipation (25°C)
65mW
Input Voltage (All inputs except ANALOG IN)
(VP + 0.5V) to -0.5V
ANALOG IN Voltage
(VP + .5V) to (VP - 10V)
DC Current into any Input
±1.0mA
Lead Temperature - Soldering, 10 sec.
300°C
ELECTRICAL CHARACTERISTICS
(-40°C ² TA ² +85°C, VP = 5V ± 10%)
PARAMETER
CONDITIONS
Frequency Detect Bandwidth
Amplitude for Detection
each tone
Twist Tolerance
Twist =
High Tone
Low Tone
MIN
TYP
MAX
UNITS
±(1.5+2Hz)
±2.3
±3.5
% of fO
-32
-2
dBm ref.
to 600Ω
-10
+10
dB
0.8
Vrms
0dB
dB*
60-Hz Tolerance
Dial Tone Tolerance
“precise” dial tone
Talk Off
MITEL tape #CM 7290
Digital Outputs
“0” level, 400µA load
0
0.5
V
(except XOUT)
“1” level, 200µA load
VP-0.5
VP
V
Digital Inputs
“0” level
0
0.3VP
V
“1” level
0.7VP
VP
V
10
mV p-p
16
mA
-12
dB*
Power Supply Noise
wide band
Supply Current
TA = 25°C
Noise Tolerance
MITEL tape #CM 7290
Input Impedance
VP³VIN³VP-10
2
10
100KΩ||15pF
* dB referenced to lowest amplitude tone
7
hits
75T204
5V Low-Power Subscriber
DTMF Receiver
MECHANICAL SPECIFICATIONS
14-Pin DIP
.050 TYP. (1.270)
.305 (7.747)
.285 (7.239)
PIN NO.1
BEVEL
.415 (10.541)
.395 (10.003)
.420 (10.668)
.390 (9.906)
.010 (0.254)
.003 (0.076)
.110 (2.794)
.092 (2.336)
.335 (8.509)
.320 (8.128)
.016 nom (0.40)
16-Pin SOL
8
75T204
5V Low-Power Subscriber
DTMF Receiver
PACKAGE PIN DESIGNATIONS
CAUTION: Use handling procedures necessary for
a static sensitive component.
(Top View)
D2
1
16
D4
D2
1
14
D4
D1
2
15
D8
D1
2
13
D8
EN
3
14
DV
EN
3
12
DV
VP
4
13
N/C
VP
4
11
ATB
N/C
5
12
ATB
N/C
5
10
XIN
N/C
6
11
XIN
XEN
6
9
XOUT
XEN
7
10
XOUT
ANALOG IN
7
8
GND
ANALOG IN
8
9
GND
75T204
14-Pin DIP
75T204
16-Pin SOL
ORDERING INFORMATION
PART DESCRIPTION
ORDER NUMBER
PACKAGING MARK
75T204
14-Pin PDIP
75T204-IP
75T204-IP
16-SOL
75T204-IL
75T204-IL
75T204
No responsibility is assumed by TDK Semiconductor Corporation for use of this product nor for any infringements of patents and trademarks
or other rights of third parties resulting from its use. No license is granted under any patents, patent rights or trademarks of TDK
Semiconductor Corporation and the company reserves the right to make changes in specifications at any time without notice. Accordingly, the
reader is cautioned to verify that the data sheet is current before placing orders.
TDK Semiconductor Corporation, 2642 Michelle Drive, Tustin, CA 92780-7019, (714) 508-8800, FAX: (714) 508-8877
1989 - 2000 TDK Semiconductor Corporation
04/24/00- rev. C
9
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