78A207
MFR1 Receiver
April 2000
DESCRIPTION
The 78A207 is a single-chip, Multi-Frequency (MF)
receiver that can detect all 15 tone-pairs, including
ST and KP framing tones. This receiver is intended
for use in equal access applications and thus meets
both Bell and CCITT R1 central office register
signaling specifications.
The 78A207 employs state-of-the-art switched
capacitor filters in CMOS technology. The receiver
consists of a bank of channel-separation bandpass
filters followed by zero-crossing detectors and
frequency-measurement
bandpass
filters,
an
amplitude check circuit, a timer and decoder circuit,
and a clock generator. The device does not attempt
to identify strings of digits by the KP (key pulse) and
ST (stop) tone pairs.
No anti-alias filtering is needed if the input signal is
band-limited to 26 KHz. The only external
component required is an inexpensive television
鈥渃olor burst鈥?3.58 MHz crystal.
The outputs interface directly with standard CMOS
or TTL circuitry and are three-state enabled to
facilitate bus-oriented architecture.
FEATURES
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Meets Bell and CCITT R1 specifications
20-pin plastic DIP
Single low-tolerance 5V supply
Detects all 15 tone-pairs including ST and KP
Long KP capability
Built-in amplitude discrimination
Excellent noise tolerance
Outputs in either 鈥渘 of 6鈥?or hexadecimal code
Three-state outputs, CMOS-compatible and
TTL-compatible
BLOCK DIAGRAM
700
VIN
900
700
THRESHOLD
DETECTOR
QUAL
LOGIC
R
Q
S
CSTR
DV
900
R
1100
1100
S
Q
DE
1300
1300
LKP
1500
1500
HEX
QUAL
1700
PRE-FILTER
X1
ZERO
CROSSING
DETECTORS
1700
BANDPASS
FILTER
D5
D4
D3
D2
X2
CLOCK
GENERATOR
CHIP CLOCKS
D1
D0
XOUT
VOLTAGE DIVIDER
VOLTAGE
REF
TONE DETECTOR
EN
AGN
VDD
DGND
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英文版
MFR1 Receiver
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英文版
MFR1 Receiver
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英文版
MFR1 Receiver
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英文版
MFR1 Receiver
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