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M-8888-01SM 데이터시트 PDF




Clare Inc.에서 제조한 전자 부품 M-8888-01SM은 전자 산업 및 응용 분야에서
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부품번호 M-8888-01SM 기능
기능 DTMF Transceiver
제조업체 Clare Inc.
로고 Clare  Inc. 로고


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M-8888-01SM 데이터시트, 핀배열, 회로
Features
· Advanced CMOS technology for low power con-
sumption and increased noise immunity
· Complete DTMF transmitter/receiver in a single
chip
Standard 8051, 8086/8 microprocessor port
· Central office quality and performance
· Adjustable guard time
· Automatic tone burst mode
· Call progress mode
· Single +5 Volt power supply
· 20-pin DIP and SOIC packages
· 2 MHz microprocessor port operation
·· Inexpensive 3.58 MHz crystal
Applications
Paging systems
· Repeater systems/mobile radio
· Interconnect dialers
· PBX systems
· Computer systems
· Fax machines
· Pay telephone
·· Credit card verification
M-8888
DTMF Transceiver
Description
The M-8888 is a complete DTMF Transmitter
Receiver that features adjustable guard time, auto-
matic tone burst mode, call progress mode, and a fully
compatible 8051, 8086/8 microprocessor interface.
The receiver portion is based on the industry standard
M-8870 DTMF Receiver, while the transmitter uses a
switched-capacitor digital-to-analog converter for low-
distortion, highly accurate DTMF signaling. Tone
bursts can be transmitted with precise timing by mak-
ing use of the automatic tone burst mode. To analyze
call progress tones, a call progress filter can be select-
ed by an external microprocessor.
Ordering Information
Part #
Description
M-8888-01P
20-pin plastic DIP
M-8888-01SM 20-pin plastic SOIC
M-8888-01T
20-pin plastic SOIC,Tape and Reel
Pin Connections
Block Diagram
DS-M8888-R1
www.clare.com
1




M-8888-01SM pdf, 반도체, 판매, 대치품
M-8888
Guard Time Adjustment
Call Progress Response
The value of tDP is a device parameter and tREC is the
minimum signal duration to be recognized by the
receiver. A value for C1 of 0.1 µF is recommended for
most applications, leaving R1 to be selected by the
designer. Different steering arrangements may be
used to select independently the guard times for tone
present (tGTP) and tone absent (tGTA). This may be nec-
essary to meet system specifications that place both
accept and reject limits on both tone duration and inter-
digit pause. Guard time adjustment also allows the
designer to tailor system parameters such as talkoff
and noise immunity. Increasing tREC improves talkoff
performance since it reduces the probability that tones
simulated by speech will maintain signal condition long
enough to be registered. Alternatively, a relatively short
tREC with a long tDO would be appropriate for extreme-
ly noisy environments where fast acquisition time and
immunity to tone dropouts are required. Design infor-
mation for guard time adjustment is shown in the
Guard Time Adjustment above.
Call Progress Filter
A call progress (CP) mode can be selected, allowing
the detection of various tones that identify the progress
of a telephone call on the network. The call progress
tone input and DTMF input are common; however, call
progress tones can only be detected when the CP
mode has been selected. DTMF signals cannot be
detected if the CP mode has been selected (see the
Actual Frequencies vs Standard Requirements on
page 5). The Call Progress Response above indicates
the useful detect bandwidth of the call progress filter.
Frequencies presented to the input (IN+ and IN-) that
are within the accept bandwidth limits of the filter are
hard-limited by a high-gain comparator with the
IRQ/CP pin serving as the output. The square wave
output obtained from the schmitt trigger can be ana-
yzed by a microprocessor or counter arrangement to
determine the nature of the call progress tone being
detected. Frequencies in the reject area will not be
detected, and consequently there will be no activity on
IRQ/CP as a result of these frequencies.
DTMF Generator
The DTMF transmitter used in the M-8888 is capable
of generating all 16 standard DTMF tone pairs with low
distortion and high accuracy. All frequencies are
derived from an external 3.58 MHz crystal. The sinu-
soidal waveforms for the individual tones are digitally
synthesized using row and column programmable
dividers and switched capacitor digital-to-analog con-
verters. The row and column tones are mixed and fil-
tered, providing a DTMF signal with low total harmonic
distortion and high accuracy. To specify a DTMF sig-
nal, data conforming to the encoding format shown in
the Tone Encoding/Decoding Table on page 3 must be
written to the transmit data register. Note that this is the
same as the receiver output code. The individual tones
that are generated (fLOW and fHIGH) are referred to as
low-group and high-group tones. Typically, the high-
group to low-group amplitude ratio (twist) is 2 dB to
compensate for high-group attenuation on long loops.
Operation:
During write operations to the transmit data register, 4-
bit data on the bus is latched and converted to a 2 of 8
code for use by the programmable divider circuitry to
specify a time segment length that will ultimately deter-
mine the tone frequency. The number of time seg-
ments is fixed at 32, but the frequency is varied by
varying the segment length. When the divider reaches
the appropriate count as determined by the input code,
a reset pulse is issued and the counter starts again.
4
www.clare.com
Rev. 1

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M-8888-01SM 전자부품, 판매, 대치품
Common Crystal Connection
Equations
Application Circuit (Single-Ended Input)
M-8888
Internal Register Functions
RS0
0
0
1
1
RD
1
0
1
0
WR Function
0 Write to transmitter
1 Read from receiver
0 Write to control register
1 Read from status register
CRA Bit Positions
b3
RSEL
b2
IRQ
b1
CP/DTMF
b0
TOUT
CRB Bit Positions
b3 b2
C/R S/D
b1
TEST
b0
BURST
Staus Register Description
Bit
b0 IRQ
Name
b1 Transmit data register empty
(burst mode only)
b2 Receive data register full.
b3 Delayed Steering
Status Flag Set
Interrupt has occurred. Bit one (b1)
and/or bit 2 (b2) is set.status register is read.
Pause duration has terminated and transmitter
is ready for new data.
Valid data is in the receive data register.
Set on valid detection of the absence of a
DTMF signal.
Rev. 1 www.clare.com
Status Flag Cleared
Interrupt is inactive. Cleared after
Cleared after status register is read or
when not in burst mode.
Cleared after status register is read.
Cleared on detection of a valid DTMF
signal.
7

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관련 데이터시트

부품번호상세설명 및 기능제조사
M-8888-01SM

DTMF Transceiver

Clare  Inc.
Clare Inc.

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