M-8870 Datasheet, PDF (1/8 Pages) Clare, Inc. – DTMF Receiver

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, re-
mote 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 technol-
ogy, 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 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 interface bus. Minimal external components required in-
clude a low-cost 3.579545 MHz color burst crystal, a timing re-
sistor, 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).
Figure 2 Block Diagram
Teltone Corporation, 22121-20th Avenue SE, Bothell, WA 98021-4408 U.S.A
40-406-00011, Rev. E
Page 1
Phone: [phone] or 425-487-1515 Fax: [phone]
E-mail: [e-mail] Internet: www.teltone.com