75T2089/2090/2091
DTMF Transceivers
April 2000
DESCRIPTION
TDK Semiconductor’s 75T2089/2090/2091 are
complete
Dual-Tone
Multifrequency
(DTMF)
Transceivers that can both generate and detect all
16 DTMF tone-pairs.
These ICs integrate the
performance-proven 75T202 DTMF receiver with a
DTMF generator circuit.
The DTMF receiver electrical characteristics are
identical
to
the
standard
75T202
device
characteristics.
The DTMF generator provides
performance similar to the Mostek MK5380, but with
an improved (tighter) output amplitude range
specification and with the addition of independent
latch and reset controls.
An additional feature of the 75T2090/2091 is
"imprecise" call progress detector. The detector
detects the presence of signals in the 305-640 Hz
band.
(continued)
FEATURES
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DTMF Generator and Receiver on one-chip
Call progress detection (2090/2091 only)
Early detect output (2091 only)
DTMF Receiver exhibits excellent speech
immunity
Analog input range from -32 to -2 dBm
(ref 600Ω )
Three-state outputs (4-bit hexadecimal) from
DTMF Receiver
AC coupled, internally biased analog input
Latched DTMF Generator inputs
DTMF output typ. -8 dBm (Low Band) and
-5.5 dBm (High Band)
Easy interface for microprocessor dialing
Uses inexpensive 3.579545 MHz crystal for
reference
Low-power 5 volt CMOS
BLOCK DIAGRAM
XIN
RS
X
1
XOUT
XEN ATB
Vp
8
BANDSPLIT
FILTERS
INTERNAL
CLOCK
ENERGY
DETECTOR
Vp
D7
D6
D5
D4
Vp
LATCH
Vp
RESET
Vp
CK
Q
DTMF
OUT
D
D
D
D
CK
Q
Q
Q
Q
DTMF
GENERATOR
DET
(2090/2091 only)
LIN
(2090/2091 only)
D CLR
BANDPASS
FILTERS
BANDPASS
FILTERS
DIN
BS1
697
AMPLITUDE
DETECTORS
TIMING
CIRCUITRY
ED
(2091 only)
770
852
941
1209
DV
STROBE
DV
F.F.
DV
BS2
1336
D3
D2
D1
D0
1477
OUTPUT
DECODER
AND
REGISTER
VOLTAGE
REF
1633
POWER REGULATOR
Vp
Vn
DE
TDK [ TDK ELECTRONICS ]
