New Quad Codec-Filter Combo Lowers Noise, Cost and Power Consumption in Voiceband Analog-to-Digital Communications
DALLAS (Feb. 2, 1998) -- Continuing its mixed-signal technological innovations, Texas Instruments today announced a new highly integrated pulse-code-modulated (PCM) codec-filter combo that supports four channels on a single chip. The device brings lower cost, extremely low noise and low power consumption to a wide variety of applications that interface analog voiceband signals to digital communications systems. Among these applications are line cards for access concentration equipment in central offices (COs) and remote sites, private branch exchanges (PBXes), digital telephone answering devices (DTADs) and other voiceband communications systems, especially those based on digital signal processors (DSPs).
The device, designated the TCM38C17 QCombo™, complements TI's existing advanced DSP-interface codec solutions in the CO switching and modem product areas. The device incorporates the industry's leading idle-channel noise performance resulting from sigma-delta analog-to-digital (A/D) and digital-to-analog (D/A) signal conversion, a unique feature among today's non-programmable combos. The QCombo's architecture is expected to be reused in many future advanced codec designs from TI.
The QCombo integrates four of TI's leading TCM29C13 combos on a single device, lowering chip counts and saving costs for original equipment manufacturers (OEMs). The QCombo provides increased voice and data line card capacity over the existing voiceband telecommunications infrastructure. This increased linecard channel capacity is key for future voice and data transmission protocols over twisted pair systems, such as DSL (digital subscriber line).
"The 'C17 QCombo provides a highly integrated and cost-effective interface solution between digital signal processing systems and the analog voiceband," said Gregory Davis, TI's Worldwide Manager of the Broadband Connectivity Development Group. "The QCombo will enable important space reductions in multichannel telecom access and emerging DSP-based voiceband applications."
TI's 'C17 QCombo makes it more economical to build multichannel line cards and other voiceband systems. "The QCombo's high-quality output will enhance signal reliability, helping to keep end users satisfied with the multitude of services they can receive through the device" said Davis.
Low Power, Less Heat
Low operational power consumption of 40 mW per channel is complemented by a power-down mode which consumes a mere 1 mW per channel, helping OEMs pack more channels into less space with less heat dissipation. The QCombo requires only a single-rail +5-volt power supply, contributing to low power consumption and eliminating the need for the second power supply required by competitive devices. A differential output drives a transformer load directly and provides an extremely wide signal swing from a single-rail codec.
The QCombo's compliance with ITU (formerly CCITT) telephony specifications assures virtually universal interoperability in line cards and other equipment with functions performed by the device. Pin-selectable u-Law or A-Law companding supports digital communications applications worldwide.
Pricing and Availability
The TCM38C17 QCombo comes in an SSOP (shrink small-outline package) package. The TCM38C17 is available now from Texas Instruments and its authorized distributors. Suggested resale pricing in quantities of 1,000 is $7.61.
More information regarding TI's central office codec products is available on the World Wide Web at 
http://www.ti.com/sc/msp.
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