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