M-8870
DTMF Receiver
Features
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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
Description
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 technology, the M-8870 offers low
power consumption (35 mW max) and precise data
handling. Its filter section uses switched capacitor
technology for both the high and low group filters and
for dial tone rejection. Its decoder uses digital counting
techniques 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 inter-
face bus. Minimal external components required
include a low-cost 3.579545 MHz color burst crystal, a
timing resistor, and a timing capacitor.
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 Tone Decoding
table on page 5).
Ordering Information
Part #
M-8870-01
M-8870-01SM
M-8870-01SMTR
M-8870-02
M-8870-02SM
M-8870-02T
Block Diagram
Description
18-pin plastic DIP
18-pin plastic SOIC
18-pin plastic SOIC, tape and reel
18-pin plastic DIP, power-down,
option
18-pin plastic SOIC, power-down,
option
18-pin plastic SOIC, power-down
option, tape and reel
Applications
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Telephone switch equipment
Remote data entry
Paging systems
Personal computers
Credit card systems
Pin Configuration
DS-M8870-R3
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