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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
Parallel-Port 16-Bit SoundPort® Stereo Codec AD1845
plete on-chip filtering, MPC Level-2 compliant analog mixing, 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, com-
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FUNCTIONAL BLOCK DIAGRAM
ANALOG
L_MIC R_MIC L_LINE R_LINE L_AUX1 R_AUX1 M U X 0 dB/ 20 dB L GAIN R GAIN ANALOG SUPPLY DIGITAL SUPPLY CLOCK SOURCE POWER DOWN RESET
DIGITAL
VARIABLE SAMPLE FREQUENCY GENERATOR ⌺⌬ A/D CONVERTER ⌺⌬ A/D CONVERTER
AD1845
-LAW A-LAW LINEAR
PLAYBACK REQ PLAYBACK ACK
FIFO
P A R A L L E L P O R T
CAPTURE REQ CAPTURE ACK ADR1:0 DATA7:0 CS RD WR BUS DRIVER CONTROL HOST DMA INTERRUPT EXTERNAL CONTROL
GAM
GAM
GAM
L_OUT M_OUT R_OUT MUTE
⌺ ⌺ ⌺
⌺
⌺
DIGITAL MIX GAM = GAIN ATTENUATE ATTENTUATE MUTE L ATTENUATE ⌺⌬ D/A ⌺ CONVERTER MUTE
⌺
GAM
⌺
GAM
R
ATTENUATE MUTE
⌺⌬ D/A CONVERTER
-LAW A-LAW LINEAR
FIFO
⌺
M_IN L_AUX2 R_AUX2
REFERENCE
CONTROL REGISTERS
VREF_F
VREF
SoundPort is a registered trademark of Analog Devices, Inc. Microsoft and Windows are registered trademarks of Microsoft Corporation.
REV. C
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. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A Tel: 781/329-4700 World Wide Web Site: http://www.analog.com Fax: 781/326-8703 © Analog Devices, Inc., 1997
AD1845–SPECIFICATIONS
STANDARD TEST CONDITIONS UNLESS OTHERWISE NOTED
Temperature Digital Supply (VDD) Analog Supply (VCC) Word Rate (FS) Input Signal Analog Output Passband ADC FFT Size DAC FFT Size VIH VIL
ANALOG INPUT
25 °C 5.0 V 5.0 V 48 kHz 1008 Hz 20 Hz to 20 kHz 2048 8192 5 V 0 V
DAC Test Conditions Calibrated 0 dB Relative to Full Scale 16-Bit Linear Mode 10 kΩ Output Load Mute Off, OL = 0 ADC Test Conditions Calibrated 0 dB Gain –1.0 dB Relative to Full Scale Line Input 16-Bit Linear Mode Min Typ 1 2.83 0.1 0.283 1 2.83 17 15 Max Units V rms V p-p V rms V p-p V rms V p-p kΩ pF
Input Voltage (RMS Values Assume Sine Wave Input) Line 2.55 MIC with +20 dB Gain (MGE = 1) 0.255 MIC with 0 dB Gain (MGE = 0) Input Impedance* Input Capacitance
PROGRAMMABLE GAIN AMPLIFIER–ADC
3.35 0.335 3.35
2.55 10
Min Step Size (All Steps Tested) (0 dB to 22.5 dB) PGA Gain Range Span 0.7 21.5
Typ 1.5 22.5
Max 1.9 23.5
Units dB dB
AUXILIARY LINE, MONO, AND MICROPHONE INPUT ANALOG GAIN/AMPLIFIERS/ATTENUATORS
Min Step Size : AUX1, AUX2, LINE, MIC (All Steps Tested) (+12 dB to –30 dB) (–31.5 dB to –34.5 dB) Step Size: M_IN (All Steps Tested) (0 dB to –39 dB) (–42 dB to –45 dB) Input Gain/Attenuation Range: AUX1, AUX2, LINE, MIC Input Gain/Attenuation Range: M_IN
DIGITAL DECIMATION AND INTERPOLATION FILTERS*
Typ 1.5 1.5 3.0 3.0 46.5 45
Max 1.75 2.0 3.6 3.85 49.0 49
Units dB dB dB dB dB dB
1.25 1 2.5 2.2 45.0 42
Min Passband Passband Ripple Transition Band Stopban.