M-8870 Datasheet PDF
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M-8870 DTMF Receiver
Low power consumption
· Adjustable acquisition and release times
· Central office quality and performance
· Power-down and inhibit modes (-02 only)
· Inexpensive 3.58 MHz time base
· Single 5 volt power supply
· Dial tone suppression
·· Applications include: telephone switch equipment,
remote data entry, paging systems, personal
computers, credit card systems
The M-8870 is a full DTMF Receiver that integrates both
bandsplit filter and decoder functions into a single 18-pin DIP
or SOIC package. Manufactured using CMOS process tech-
nology, the M-8870 offers low power consumption (35 mW max)
and precise data handling. Its filter section uses switched ca-
pacitor technology for both the high and low group filters and
for dial tone rejection. Its decoder uses digital counting tech-
niques to detect and decode all 16 DTMF tone pairs into a 4-
bit code. External component count is minimized by provision
of an on-chip differential input amplifier, clock generator, and
latched tri-state interface bus. Minimal external components
required include a low-cost 3.579545 MHz color burst crystal,
a timing resistor, and a timing capacitor.
Figure 1 Pin Connections
The M-8870-02 provides a “power-down” option which, when
enabled, drops consumption to less than 0.5 mW.The M-8870-
02 can also inhibit the decoding of fourth column digits (see
Table 5).
40-406-00011, Rev. F
Figure 2 Block Diagram
Page 1
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