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Parallel-Port 16-Bit SoundPort Stereo Codec AD1845

FEATURES Single-Chip Integrated ∑∆ Digital Audio Stereo Codec Microsoft* and Windows* Sound System Compatible MPC Level-2+ Compliant Mixing 16 mA Bus Drive Capability Supports Two DMA Channels for Full Duplex Operation On-Chip Capture and Playback FIFOs Advanced Power-Down Modes Programmable Gain and Attenuation Sample Rates from 4.0 kHz to 50 kHz Derived from a Single Clock or Crystal Input 68-Lead PLCC, 100-Lead TQFP Packages Operation from +5 V Supplies Byte-Wide Parallel Interface to ISA and EISA Buses Pin Compatible with AD1848, AD1846, CS4248, CS4231

programmable gain, attenuation and mute, a variable sample frequency generator, FIFOs, and supports advanced powerdown modes. It provides a direct, byte-wide interface to both ISA (“AT”) and EISA computer buses for simplified implementation on a computer motherboard or add-in card. The AD1845 SoundPort Stereo Codec supports a DMA request/grant architecture for transferring data with the host computer bus. One or two DMA channels can be supported. Programmed I/O (PIO) mode is also supported for control register accesses and for applications lacking DMA control. Two input control lines support mixed direct and indirect addressing of thirty-seven internal control registers over this asynchronous interface. The AD1845 includes dual DMA count registers for full duplex operation enabling the AD1845 to capture data on one DMA channel and play back data on a separate channel. The FIFOs on the AD1845 reduce the risk of losing data when making DMA transfers over the ISA/EISA bus. The FIFOs buffer data transfers and allow for relaxed timing in acknowledging requests for capture and playback data.

PRODUCT OVERVIEW

The Parallel Port AD1845 SoundPort® Stereo Codec integrates key audio data conversion and control functions into a single integrated circuit. The AD1845 provides a complete, single chip computer audio solution for business audio and multimedia applications. The codec includes stereo audio converters, complete on-chip filtering, MPC Level-2 compliant analog mixing,

External circuit requirements are limited to a minimal number of low cost support components. Antimaging DAC output filters are incorporated on-chip. Dynamic range exceeds 80 dB over the 20 kHz audio band. Sample rates from 4 kHz to 50 kHz are supported from a single external crystal or clock source.

  • Microsoft is a registered trademark of Microsoft Corporation. Windows is a trademark of Microsoft Corporation. SoundPort is a registered trademark of Analog Devices, Inc.

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FUNCTIONAL BLOCK DIAGRAM ANALOG L_MIC R_MIC

ANALOG SUPPLY

DIGITAL SUPPLY

0 dB/ 20 dB

L_AUX1 R_AUX1

GAM

M_IN

L_OUT MUTE

GAM

GAM

GAIN

∑∆ A/D CONVERTER

R

L ATTENUATE MUTE

µ-LAW A-LAW LINEAR

∑∆ D/A CONVERTER

∑ GAM

ATTENUATE MUTE

P A R A L L E L

∑∆ D/A CONVERTER

µ-LAW A-LAW LINEAR

FIFO

P O R T

DATA7:0 CS

WR BUS DRIVER CONTROL HOST DMA INTERRUPT EXTERNAL CONTROL

GAM

L_AUX2 R_AUX2

CAPTURE ACK ADR1:0

RD ∑

∑ R

CAPTURE REQ

FIFO

DIGITAL MIX ATTENUATE

GAM = GAIN ATTENTUATE MUTE

PLAYBACK REQ PLAYBACK ACK

∑∆ A/D CONVERTER

GAIN

M U X

R_LINE

R_OUT

L

DIGITAL

RESET

AD1845

VARIABLE SAMPLE FREQUENCY GENERATOR

L_LINE

M_OUT

POWER DOWN

CLOCK SOURCE

REFERENCE

VREF_F

CONTROL REGISTERS

VREF

REV. B Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

© Analog Devices, Inc., 1996 One Technology Way, P.O. Box 9106, Norwood. MA 02062-9106, U.S.A. Tel: 617/329-4700 Fax: 617/326-8703


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