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The AD1803/AD1804 chipset allows the implementation of a
low-cost full Modem DAA Line Interface and codec with mini-
mal external components. The AD1803 can also be used as a
stand-alone codec for voice/handset/telephony applications, or
as a cellular telephone interface.
The AD1803 is an Intel AC’97 Rev 2.1-compliant modem codec
(refer to Intel’s AC’97 speciﬁcations at www.intel.com) with
selectable AC’97 or a DSP-style serial interface.
The AD1803 codec uses high-performance sigma-delta ADC
and DACs with programmable gain/attenuation. It has a digital
monitor output with selectable mix from ADC and DAC chan-
nels for call progress monitoring. The AD1803 supports ring
validation and wake-up interrupt output signalling. The AD1803
has programmable ﬁlters dedicated to impedance synthesis and
when used with the AD1804, it provides a complete digital line
termination impedance synthesis control loop.
The AD1804 is a solid-state line-side analog phone interface
device that replaces a conventional discrete DAA. The AD1804
eliminates the need for transformer, relays, opto-isolators and a
2-to-4-wire hybrid. The AD1804 uses high-performance sigma-
delta ADC and DACs with programmable gain/attenuation. It
has digitally selectable line termination impedances.
Low Power Modem Codec AD1803 and Silicon DAA
AD1803 Can Be Used as a Stand-Alone Modem/Voice/
Intel AC’97 Rev 2.1-Compliant Modem Codec
AC’97 or DSP Style Serial Interface
Supports all Modem/Fax Standards Including V.90
Software Programmable DAA and Compliant with U.S.
FCC and CTR21 Approved
Capacitively Coupled Clock and Data Interface Across
Multiple Crystal/Clock Rates Supported
Programmable Gain, Attenuation and Mute
On-Chip Signal Filters
Telephony Codec Independent of the AD1804
and International PTT Standards
Digital Interpolation and Decimation Filters
Analog Output Low Pass
The AD1804 features a Ring Detect comparator making the
chipset capable of ring and line reversal detection and validation.
The Ring/CID Buffer allows any line signal, whether ring, line
reversal, or even Caller ID data, to be sampled and driven directly
into the codec’s main ADC channel for processing independent of
The AD1804’s dc line-hold current DAC, dc line voltage sense
ADC and the hold current regulator supports off-hook and pulse
dialing functions in addition to meeting the dc hold require-
ments of a given country. The AD1804 CTR21 circuit allows
the implementation of a high power dc shunt path without the
need for costly external high-power transistors to ensure compli-
ance to CTR21 DC hold current limit requirements.
The AD1804 hybrid provides 2-to-4-wire conversion, local echo
cancellation and correctly terminates the transmission line.
The AD1803/AD1804 chipset features Analog Device’s pro-
prietary isolation barrier techniques using low-cost high-voltage
capacitors to meet US and international isolation requirements.
The AD1803/AD1804 supports several advanced power manage-
ment features with several power-saving modes. The chipset also
supports wake-up on ring from D3-Cold system state.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Programmable Sample Rates
Digital Monitor Speaker Output
Integrated Ring Detector and Support for Soft Caller-ID
24-Lead TSSOP Package
Modems (PC and Embedded)
Voice and Telephony
Fax Machines, Answering Machines, Speakerphones
Operation from 3.3 V or 5 V Supply
Advanced Power Management
From 6.4 kHz to 16 kHz
With 1 Hz, 8/7 Hz and 10/7 Hz Resolution
Supports Wake-Up on Ring from D3-Cold System State
m CMOS Technology
DAA Line Codec Chipset
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© Analog Devices, Inc., 2000