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Multi-standard modem includes enhanced DTMF decoder

Winston-Salem, NC&#8212CML Microcircuits' CMX867A, a V.22 multi-standard modem IC for telephone-based information systems, includes an enhanced DTMF decoder, thus affording a more compact design and reducing bill-of-material costs.



The CMX867A's “high-quality” DTMF decoder, for industrial control and security systems, telephone telemetry and advanced payphones offer high immunity to falsing on voice. A high-speed serial bus, compatible with standard micrcontroller interfaces, facilitates control and data transfer. Data is transferred in 8-bit bytes or 16-bit words (user selected) via on-chip, programmable Tx and Rx USARTs. Supported formats are either transparent synchronous data or multi-format asynchronous data compatible with ITU V.14 recommendations.

The device, powered from a low-voltage (2.7 to 5.5 volt) source, features a ringing-signal/line-reversal detector that functions even when the device is in its Powersave mode, thus providing an interrupt which
can be used to wake-up the host controller when appropriately commanded. A hook-switch/relay-drive output, software gain controls, and DTMF transmit twist compensation are included. The modem's line-drivers and a receiver hybrid are integrated on-chip, requiring a minimum of (passive) external components to operate in a 2-wire or 4-wire line interface application.

Compliant with ITU and Bell recommendations, the CMX867A is backward compatible with the company's CMX867, allowing existing users to re-use their current software and hardware designs. Click here, and key in CMX867A in the search bar to access the device's “short spec” sheet and to request the device's full datasheet. The CMX867A, available in 24-pin TSSOP, SOIC, and DIP packages, is priced at $2.50.

CML Microcircuits , 1-336-744-5050, www.cmlmicro.com

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