Electronic Components Datasheet Search
  English  ▼
ALLDATASHEET.NET

X  

M-8870-01SMTR Datasheet(PDF) 3 Page - Clare, Inc.

Part # M-8870-01SMTR
Description  DTMF Receiver
Download  9 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  CLARE [Clare, Inc.]
Direct Link  http://www.clare.com
Logo CLARE - Clare, Inc.

M-8870-01SMTR Datasheet(HTML) 3 Page - Clare, Inc.

  M-8870-01SMTR Datasheet HTML 1Page - Clare, Inc. M-8870-01SMTR Datasheet HTML 2Page - Clare, Inc. M-8870-01SMTR Datasheet HTML 3Page - Clare, Inc. M-8870-01SMTR Datasheet HTML 4Page - Clare, Inc. M-8870-01SMTR Datasheet HTML 5Page - Clare, Inc. M-8870-01SMTR Datasheet HTML 6Page - Clare, Inc. M-8870-01SMTR Datasheet HTML 7Page - Clare, Inc. M-8870-01SMTR Datasheet HTML 8Page - Clare, Inc. M-8870-01SMTR Datasheet HTML 9Page - Clare, Inc.  
Zoom Inzoom in Zoom Outzoom out
 3 / 9 page
background image
M-8870
www.clare.com
3
Rev. 3
Basic Steering Circuit
Single-Ended Input Configuration
Functional Description
M-8870 operating functions (see block diagram on
page 1) include a bandsplit filter that separates the
high and low tones of the received pair, and a digital
decoder that verifies both the frequency and duration
of the received tones before passing the resulting 4-bit
code to the output bus.
Filter
The low and high group tones are separated by apply-
ing the dual-tone signal to the inputs of two 6th order
switched capacitor bandpass filters with bandwidths
that correspond to the bands enclosing the low and
high group tones. The filter also incorporates notches
at 350 and 440 Hz, providing excellent dial tone rejec-
tion. Each filter output is followed by a single-order
switched capacitor section that smooths the signals
prior to limiting. Signal limiting is performed by high-
gain comparators provided with hysteresis to prevent
detection of unwanted low-level signals and noise.
The comparator outputs provide full-rail logic swings
at the frequencies of the incoming tones.
Decoder
The M-8870 decoder uses a digital counting tech-
nique to determine the frequencies of the limited tones
and to verify that they correspond to standard DTMF
frequencies. A complex averaging algorithm is used to
protect against tone simulation by extraneous signals
(such as voice) while tolerating small frequency varia-
tions. The algorithm ensures an optimum combination
of immunity to talkoff and tolerance to interfering sig-
nals (third tones) and noise. When the detector rec-
ognizes the simultaneous presence of two valid tones
(known as signal condition), it raises the Early
Steering flag (ESt). Any subsequent loss of signal
condition will cause ESt to fall.
Steering Circuit
Before a decoded tone pair is registered, the receiver
checks for a valid signal duration (referred to as char-
acter-recognition-condition). This check is performed
by an external RC time constant driven by ESt. A logic
high on ESt causes VC (see block diagram on page 1)
to rise as the capacitor discharges. Provided that sig-
nal condition is maintained (ESt remains high) for the
validation period (t
GTF), VC reaches the threshold (VTSt)
of the steering logic to register the tone pair, thus latch-
ing
its
corresponding
4-bit
code
(see
DC
Characteristics on page 2) into the output latch. At this
point, the GT output is activated and drives V
C to VDD.
GT continues to drive high as long as ESt remains
high. Finally, after a short delay to allow the output
latch to settle, the delayed steering output flag (StD)
goes high, signaling that a received tone pair has been
registered. The contents of the output latch are made
available on the 4-bit output bus by raising the three-
state control input (OE) to a logic high. The steering
circuit works in reverse to validate the interdigit pause
between signals. Thus, as well as rejecting signals too
short to be considered valid, the receiver will tolerate
signal interruptions (dropouts) too short to be consid-
ered a valid pause. This capability, together with the
ability to select the steering time constants externally,
allows the designer to tailor performance to meet a
wide variety of system requirements.


Similar Part No. - M-8870-01SMTR

ManufacturerPart #DatasheetDescription
logo
List of Unclassifed Man...
M-8870-01SMTR ETC2-M-8870-01SMTR Datasheet
255Kb / 8P
   DTMF Receiver
logo
Clare, Inc.
M-8870-01SMTR CLARE-M-8870-01SMTR Datasheet
307Kb / 9P
   DTMF Receiver
More results

Similar Description - M-8870-01SMTR

ManufacturerPart #DatasheetDescription
logo
Sanyo Semicon Device
LC7387M SANYO-LC7387M Datasheet
114Kb / 6P
   DTMF Receiver?
logo
List of Unclassifed Man...
HM9202 ETC1-HM9202 Datasheet
79Kb / 1P
   DTMF RECEIVER
logo
Holtek Semiconductor In...
HT9170B HOLTEK-HT9170B_02 Datasheet
187Kb / 13P
   DTMF Receiver
logo
List of Unclassifed Man...
M-8870 ETC2-M-8870 Datasheet
255Kb / 8P
   DTMF Receiver
logo
ELAN Microelectronics C...
HM9270C EMC-HM9270C Datasheet
66Kb / 10P
   DTMF RECEIVER
logo
List of Unclassifed Man...
MS8870 ETC-MS8870 Datasheet
138Kb / 8P
   DTMF Receiver
logo
Silan Microelectronics ...
SC9270C SILAN-SC9270C Datasheet
177Kb / 12P
   DTMF RECEIVER
logo
Sanyo Semicon Device
LC73872M SANYO-LC73872M Datasheet
115Kb / 6P
   DTMF Receiver?
logo
Holtek Semiconductor In...
HT9170 HOLTEK-HT9170 Datasheet
124Kb / 12P
   DTMF Receiver
logo
Sanyo Semicon Device
LC7385 SANYO-LC7385 Datasheet
164Kb / 7P
   DTMF Receiver
logo
Holtek Semiconductor In...
HT9170B HOLTEK-HT9170B_09 Datasheet
136Kb / 14P
   DTMF Receiver
More results


Html Pages

1 2 3 4 5 6 7 8 9


Datasheet Download

Go To PDF Page


Link URL




Privacy Policy
ALLDATASHEET.NET
Does ALLDATASHEET help your business so far?  [ DONATE ] 

About Alldatasheet   |   Advertisement   |   Contact us   |   Privacy Policy   |   Link Exchange   |   Manufacturer List
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com