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M-88L70 Dataheets PDF



Part Number M-88L70
Manufacturers Clare Inc.
Logo Clare  Inc.
Description 3V DTMF Receiver
Datasheet M-88L70 DatasheetM-88L70 Datasheet (PDF)

M-88L70 3V DTMF Receiver Features • Operates between 2.7 and 3.6 volts • Low power consumption • Power-down mode • Inhibit mode • Central office quality and performance • Inexpensive 3.58 MHz time base • Adjustable acquisition and release times • Dial tone suppression • Functionally compatible with Clare’s M-8870 Applications • Telephone switch equipment • Mobile radio • Remote control • Paging systems • PCMCIA • Portable TAD • Remote data entry The M-88L70 is a full DTMF Receiver that integrate.

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M-88L70 3V DTMF Receiver Features • Operates between 2.7 and 3.6 volts • Low power consumption • Power-down mode • Inhibit mode • Central office quality and performance • Inexpensive 3.58 MHz time base • Adjustable acquisition and release times • Dial tone suppression • Functionally compatible with Clare’s M-8870 Applications • Telephone switch equipment • Mobile radio • Remote control • Paging systems • PCMCIA • Portable TAD • Remote data entry The M-88L70 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-88L70 offers low power consumption (18 mW max), precise data handling and 3V operation. 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 interface bus. Minimal external components required include a low-cost 3.579545 MHz color burst crystal, a timing resistor, and a timing capacitor. Figure 2 Block Diagram Description The M-88L70 monolithic DTMF receiver offers small size, low power consumption and high performance, with 3 volt operation. Its architecture consists of a bandsplit filter section, which separates the high and low group tones, followed by a digital counting section which verifies the frequency and duration of the received tones before passing the corresponding code to the output bus. Ordering Information Part # M-88L70-01P M-88L70-01S M-88L70-01T Description 18-pin plastic DIP 18-pin SOIC 18-pin SOIC, Tape and Reel Figure 1 Pin Connections DS-M88L70-R1 www.clare.com 1 M-88L70 Filter The low and high group tones are separated by applying the dual-tone signal to the inputs of two 9th 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 rejection. Each filter output is followed by a single-order switched capacitor section that smoothes 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-88L70 decoder uses a digital counting technique 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 variations. The algorithm ensures an optimum combination of immunity to talkoff and tolerance to interfering signals (third to.


M-8888 M-88L70 M-959


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