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
• 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
INTERNAL
CLOCK
ATBXEN
RS
X
1
XOUTXIN
LIN
(2090/2091 only)
D7
D6
D5
D4
LATCH
RESET
DIN
Vp Vn DE
D0
D1
D2
D3
DV
ED
(2091 only)
DTMF
OUT
DET
(2090/2091 only)
POWER REGULATOR
VOLTAGE
REF
BS1
BS2
697
770
852
941
1209
1336
1477
1633
BANDPASS
FILTERS
AMPLITUDE
DETECTORS
BANDPASS
FILTERS
Vp
Vp
Vp
D Q
D Q
D Q
D Q
CK
CK
D
Q
CLR
DTMF
GENERATOR
BANDSPLIT
FILTERS
8
Vp
ENERGY
DETECTOR
Vp
TIMING
CIRCUITRY
DV
STROBE
DV
F.F.
OUTPUT
DECODER
AND
REGISTER