Copyright 2000 National Semiconductor Corp.

1

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SC14425

Complete Baseband processor for DECT Base Stations

with Caller-id and Handsfree

General Description

The SC14425SC14425 is a 3.3 Volt CMOS IC optimized

to handle all the audio, signal and data processing needed

within a DECT base station. An ADPCM transcoder, a

very low power 14 bit Codec and Analog Frontend are in-

tegrated. Direct connections towards analog or ISDN line

interface.

The SC14425 has an on-chip dedicated flexible DSP op-

timized for telecom applications caller-id, handsfree and

allows easy connection to digital telephone answering

machine devices.

The SC14425 is designed to be compatible with many

radio interfaces. A dedicated TDMA controller handles all

physical layer slot formats and radio control. The integrat-

ed National Semiconductor’s standard CR16B processor

core takes care of all the higher protocol stack. Program-

mable I/O ports can be configured as chip selects for I/O

expanders, Serial Flashes, interrupt source or I/O. A dig-

ital serial interface can be configured to interface to indus-

try-standard c odecs and ISDN devices with

linear or transparent data formats.

Features

n Integrated DECT base band transceiver optimized for

GAP base stations according to ETS 300 175-2,3 & 8.

n 2.7 to 3.3 Volt operating voltage.

essor with In System Emulation (ISE) mode.

n On-chip 6kByte Data Memory.

n Embedded flexible dedicated DSP executing Caller-id

(CID), Caller-id on Call Waiting (CIDCW) and hands-

free, two echo cancellers, two echo suppressors, ex-

tended DTMF detection, DTMF generation, sidetone

and artificial echo loss.

n Two full duplex 32 kbits/sec ADPCM transcoder.

n On-chip Dedicated Instruction Processor (DiP) for all

TDMA based events, which supports 1.152MHz,

0.576MHz and 0.288MHz data rates.

n Protected and unprotected full and double slot B-fields

n Standard DECT encryption with different keys for

different MAC-connections.

n At least 6 MAC connections can be handled simultane-

ously.

n Flexible three wire interface to radio front synthesizer.

n One 14-bit linear CODEC with programmable gain

n Peak hold ADC for RSSI measurement

n Two input 8 bit successive approximation ADC.

n Three general purpose I/O ports with programmable in-

terrupts

n Flexible 8 kHz synchronous Serial interface to external

codecs and ISDN interface circuits.

n Two general purpose timers and watch dog timer.

n Programmable chip selects to 8 bit wide ROM, SRAM

NAND Flash Memory and I/O expanders.

n Two Capture timers for frequency measurement for

e.g. metering, ringing and call progress tone detection.

n 100 pin TQFP-100 package.

Note 1:

CompactRISC

poration,

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System Diagram

sc14404

ISDN or

Data

Interface

PSTN

Interface

PSTN

Interface

sc14425

CID

Handsfree

ISDN

PSTN1

PSTN2

sc14404

sc14404

sc14404

sc14404

PRELIMINARY

FEBRUARY 2000