SANTA CLARA, CALIF. National Semiconductor is marketing its first single-chip digital cordless-telephony baseband processors for the 900-MHz and 2.4-GHz ISM band, the SC14404 (handset) and SC14425 (basestation).
John Pol, strategic marketing manager, cordless products, said the chips use digital signal processing (DSP) techniques to enable features such as "hands-free," caller-ID and multihandset support. The SC14404 and SC14425 integrate multiple DSP blocks, a RISC microprocessor and 320 kbytes of embedded flash on-chip. Together with National's LMX3162 single-chip 2.4-GHz radio transceiver, the baseband ICs provide a complete chip set for digital cordless phones.
A programmable RF interface enables the SC14404 to meet FCC requirements for 900-MHz and 2.4-GHz cordless voice and data applications, as well as the 1.9-GHz DECT standard. The handset chip also includes two voltage regulators, a dc/dc converter, battery management and direct microspeaker control.
Pol said the talk time of a cordless handset with the SC14404 and standard 450-milliamp-per-hour batteries is up to 15 hours. Standby time is more than a week.
The SC14425 basestation chip can support two handsets with a 900-MHz radio and up to nine handsets with a 2.4-GHz radio. OEMs can use the National chips to configure a 1/4-bit-rate basic model with two handsets on a basestation, a 1/2-bit-rate midrange model with five handsets on a one- or two-line base station and, by adding an extra DSP chip, a full bit-rate high-end system with up to nine handsets on a four-line base station.
Pol said the SC14425 supports different versions of CID and "hands-free" in the basestation. An integrated CR16 RISC controller handles the software protocols and high-end MMI. He added that customers can include a telephone answering machine by adding an external 32-Mbit (15-minute recording) flash memory IC to the baseband. The CR16 will support the answering machine for two lines simultaneously.
The SC14404 is priced at $13.60 and the SC14425 at $7.60 in 1,000-piece quantities. Each is packaged in a 100-lead TQFP. The SC14404 is also available in a 10-mm x 10-mm micro-BGA.
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EETInfo No. 604