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Analog Devices Inc. AD1981AJST-REEL
- Part No.:
- AD1981AJST-REEL
- Manufacturer:
- Analog Devices Inc.
- Category:
- CODECS
- Package:
- 48-LQFP
- Datasheet:
-
AD1981AJST-REEL.pdf
- Description:
- IC CODEC STEREO MICPREAMP 48LQFP
- Quantity:
- Payment:
- Shipping:
Inventory:6,000
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Product details
Overview
AD1981AJST-REEL from Analog Devices is an AC '97 2.2-compliant stereo audio codec IC with integrated 20-bit DACs, 16-bit ADCs, stereo headphone amplifier, S/PDIF output, and jack sense support in a 48-lead LQFP package. It delivers >90 dB dynamic range, supports variable sample rates from 7.04 kHz to 48 kHz, and enables full-duplex audio processing for PC motherboard and desktop audio subsystems.
For engineers reviewing the AD1981AJST-REEL datasheet, AD1981AJST-REEL pinout, AD1981AJST-REEL application, or AD1981AJST-REEL equivalent, key selection criteria include AC '97 link interface timing compliance, dual power supply (3.3 V DVDD / 5 V AVDD), 48-pin LQFP mechanical compatibility, and integrated microphone preamp programmability with 20 dB boost capability.
Technical Context
The AD1981AJST-REEL implements a dual-domain architecture: digital AC '97 serial interface (BIT_CLK, SYNC, SDATA_IN/OUT) synchronized to a 24.576 MHz crystal input, and analog signal chain with independent 20-bit DACs (LINE_OUT, HP_OUT, MONO_OUT) and 16-bit ADCs (MIC_IN, LINE_IN, CD, AUX, PHONE_IN). Its PLL-based clock generator derives all internal clocks from XTL_IN.
It features hardware jack sense (JS0/JS1) for automatic output routing, EAPD control for external amplifier shutdown, and programmable VREFOUT (2.25 V nominal, 5 mA drive) for microphone bias and power amp reference. Power-down states are controlled via register 26h (PR0–PR6 bits), enabling granular current reduction down to 1 mA in full sleep mode.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Audio Interface | AC '97 2.2-compliant serial link (BIT_CLK = 12.288 MHz, SYNC = 48 kHz) |
| DAC Resolution | 20-bit, supporting >85 dB A-weighted dynamic range at 48 kHz |
| ADC Resolution | 16-bit, delivering >80 dB A-weighted dynamic range with 90 dB SNR |
| Sample Rate Range | 7.04 kHz to 48 kHz with 1 Hz resolution, programmable via registers 2Ch/32h |
| Headphone Drive | Integrated stereo amplifier, 1 Vrms full-scale into 32 Ω load |
| Power Supplies | Separate 3.3 V DVDD and 5.0 V AVDD rails; 555 mW typical active power dissipation |
| S/PDIF Output | Dedicated SPDIF pin (Pin 48), 20-bit data format, 44.1/48 kHz support |
| Package | 48-lead LQFP (ST-48), 7 mm × 7 mm, 0.5 mm pitch |
Pinout & Package
AD1981AJST-REEL is housed in a 48-lead thin quad flatpack (LQFP) package, designated ST-48 per Analog Devices' ordering guide. Thermal resistance is JA = 76.2°C/W; operating ambient temperature range is 0°C to +70°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| XTL_IN / XTL_OUT | Clock Input/Output | Accepts 24.576 MHz crystal or external clock; drives crystal oscillator circuit |
| SDATA_IN / SDATA_OUT | AC '97 Serial Data | Full-duplex bidirectional data stream between host controller and codec |
| BIT_CLK / SYNC / RESET | AC '97 Link Timing | Provides bit clock (12.288 MHz), frame sync (48 kHz), and hardware reset |
| LINE_OUT_L/R, HP_OUT_L/R, MONO_OUT | Analog Outputs | Dedicated line-level (10 kΩ load), headphone (32 Ω), and mono telephony outputs |
| MIC_IN, LINE_IN_L/R, CD_L/R, AUX_L/R, PHONE_IN | Analog Inputs | Seven configurable analog inputs with programmable gain/attenuation (±34.5 dB range) |
| JS0 / JS1 | Jack Sense Inputs | Digital inputs detecting plug insertion for automatic output switching (e.g., headphones → speakers) |
| EAPD | External Amp Power-Down | Open-drain output controlling external Class-D or AB amplifier enable/disable |
| VREFOUT | Programmable Bias Reference | 2.25 V ±0.2 V output, 5 mA drive capability for mic bias or external amp Vbias |
Key Features
| Feature | Design Value |
|---|---|
| AC '97 2.2 Compliance | Fully compliant with Intel AC '97 2.2 specification, including register map, timing, and link protocol |
| Variable Sample Rate Engine | Independent DAC and ADC sample rate generators (registers 2Ch/32h), enabling asynchronous full-duplex operation |
| Integrated Headphone Amplifier | On-chip stereo amplifier eliminates need for external op-amps; supports 32 Ω loads at 1 Vrms |
| Digital Equalizer | Built-in 5-band parametric EQ (registers 60h/62h) for speaker optimization without host CPU intervention |
| Jack Sense Automation | Hardware-level detection (JS0/JS1) triggers automatic routing-no driver polling or interrupt latency |
| Low-Power States | Six programmable power-down modes (register 26h), reducing current from 53 mA to 1 mA in full sleep |
Applications
| Desktop PC Audio Subsystem | Industrial Thin Client Terminal |
|---|---|
Use Scenario: Integrated audio on ATX motherboard with front-panel headphone jack and rear-line-out ports. IC Role / Device Role / Timing Role: Primary AC '97 codec interfacing with southbridge; handles all analog I/O, sample rate conversion, and jack detection. Use Value: Eliminates discrete op-amps and external clock buffers; reduces BOM count by 7+ components while maintaining >90 dB SNR. | Use Scenario: Fanless industrial terminal requiring low-noise audio playback for status alerts and voice prompts. IC Role / Device Role / Timing Role: Standalone audio interface connected to ARM-based SoC via AC '97 link; manages mono speaker output and MIC input for voice command capture. Use Value: Enables reliable 7.04–48 kHz sample rate flexibility and 1 mA deep-sleep current for energy-constrained deployments. |
| Legacy Embedded Media Player | VoIP Desktop Phone Base Station |
Use Scenario: Discontinued OEM media player using AC '97-compatible chipset needing long-lifecycle audio solution. IC Role / Device Role / Timing Role: Codec providing stereo line-in recording, CD-quality playback, and headphone monitoring with ground-sense CD input. Use Value: Maintains legacy AC '97 software stack compatibility while delivering 20-bit DAC fidelity and 90 dB SNR for archival audio reproduction. | Use Scenario: SIP-enabled desktop phone with headset jack, speakerphone, and telephone line interface. IC Role / Device Role / Timing Role: Dual-role codec: processes PCM from VoIP stack (DAC path) and digitizes handset/line audio (ADC path); uses MONO_OUT and PHONE_IN with built-in preamp. Use Value: Integrates programmable 20 dB mic preamp, EAPD-controlled speaker amp, and jack-sense–driven mute for seamless headset/speakerphone handover. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar audio codec applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD1981BASTZ-REEL | Pin-compatible revision with enhanced ESD protection (HBM 4 kV), identical AC '97 functionality and register map | No change in system integration; same PCB layout and firmware | Select when higher robustness against handling damage is required without design modification |
| WM8775SEDS/V | Multi-format codec (I²S/Left-Justified/Right-Justified), no native AC '97 link; requires bridge logic or host-side protocol translation | Requires firmware rewrite and interface redesign; lacks jack sense and EAPD pins | Consider only for new designs abandoning AC '97; not drop-in for AD1981AJST-REEL |
Compared with AD1981BASTZ-REEL, the AD1981AJST-REEL offers identical audio performance but lower ESD immunity; versus WM8775SEDS/V, it provides native AC '97 compliance and hardware jack sense-critical for legacy PC audio and plug-and-play headset support without host CPU overhead.
Availability
AD1981AJST-REEL is available at Aetrix Electronics and suitable for desktop motherboard design, industrial thin client terminals, legacy embedded media players, and VoIP desktop phone base stations requiring stable component supply and long-term obsolescence management.
Supply support for AD1981AJST-REEL includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices, Inc. is a global semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies.
The AD1981A product line was designed specifically for AC '97-compliant PC audio subsystems, emphasizing integration of codec, headphone amp, S/PDIF, and jack sense in a single 48-pin LQFP to reduce motherboard real estate and BOM cost.
FAQ
What is the primary interface standard supported by the AD1981AJST-REEL?
The AD1981AJST-REEL implements the AC '97 2.2 specification as its primary digital audio interface. It uses BIT_CLK (12.288 MHz), SYNC (48 kHz), SDATA_IN, and SDATA_OUT signals to communicate with a host controller such as a southbridge or audio hub. The AD1981AJST-REEL does not support I²S, PCM, or TDM natively - all configuration and data transfer occur through the AC '97 link protocol defined in registers 00h–7Eh.
Does the AD1981AJST-REEL support variable sample rates for both playback and recording simultaneously?
Yes, the AD1981AJST-REEL supports independent variable sample rates for DAC and ADC paths. Register 2Ch (PCM Front DAC Rate) and register 32h (PCM L/R ADC Rate) each provide 16-bit fields enabling rates from 7.04 kHz to 48 kHz in 1 Hz increments. This allows true asynchronous full-duplex operation - for example, playing back at 44.1 kHz while recording at 8 kHz - without requiring shared clock domains or resampling in the host.
What are the power supply requirements for the AD1981AJST-REEL?
The AD1981AJST-REEL requires two separate supplies: 3.3 V ±0.15 V for digital circuits (DVDD1/DVDD2) and 5.0 V ±0.3 V for analog sections (AVDD1/AVDD2/AVDD3/AVDD4). Absolute maximum ratings specify –0.3 V to +3.6 V on DVDD and –0.3 V to +6.0 V on AVDD. The AD1981AJST-REEL draws 53 mA from AVDD and 47 mA from DVDD in fully active mode, dropping to 1 mA in full power-down (PR6–PR0 = 1).
How does the jack sense functionality work on the AD1981AJST-REEL?
The AD1981AJST-REEL provides two dedicated jack sense inputs (JS0 and JS1) that monitor voltage levels on attached audio connectors. These pins feed directly into register 72h (JACK SENSE), where status bits reflect plug detection state. When a headset is inserted, JS0/JS1 transitions trigger automatic routing - muting LINE_OUT and enabling HP_OUT - without host CPU polling. This hardware-level response ensures zero-latency switching and eliminates driver dependency for basic plug/unplug events.
Can the AD1981AJST-REEL drive a 32 Ω headphone load directly?
Yes, the AD1981AJST-REEL integrates a stereo headphone amplifier capable of delivering 1 Vrms full-scale output into a 32 Ω load, as specified in the "ANALOG OUTPUT" section of the datasheet. The HP_OUT_L and HP_OUT_R pins are designed for direct connection to stereo headphones without external buffering. Performance metrics include –75 dB THD at full scale and >90 dB dynamic range, meeting CD-quality playback requirements for consumer desktop systems.
AD1981AJST-REEL Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- SoundMAX®
- Package/Case:
- 48-LQFP
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Type:
- Audio Codec '97
- Data Interface:
- Serial
- Resolution (Bits):
- 16, 20 b
- Number of ADCs / DACs:
- 4 / 2
- Sigma Delta:
- No
- S/N Ratio, ADCs / DACs (db) Typ:
- -
- Dynamic Range, ADCs / DACs (db) Typ:
- 85 / 90
- Voltage - Supply, Analog:
- 4.65V ~ 5.25V
- Voltage - Supply, Digital:
- 3.15V ~ 3.45V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 48-LQFP (7x7)
AD1981AJST-REEL FAQ
1.How can I place an order for AD1981AJST-REEL through Aetrix?
Please submit a Request for Quotation (RFQ) for AD1981AJST-REEL on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for AD1981AJST-REEL reliable?
The price and inventory of AD1981AJST-REEL are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD1981AJST-REEL is usually 5 days.
3.What payment methods are accepted for AD1981AJST-REEL?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD1981AJST-REEL transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD1981AJST-REEL?
AD1981AJST-REEL orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD1981AJST-REEL order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for AD1981AJST-REEL?
For technical support, including AD1981AJST-REEL datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD1981AJST-REEL requirements.
6.How does Aetrix verify that AD1981AJST-REEL is sourced from the original manufacturer or authorized distributors?
All AD1981AJST-REEL products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that AD1981AJST-REEL meets industry standards.
7.What is the process for return or replacement of AD1981AJST-REEL?
All AD1981AJST-REEL units undergo pre-shipment inspection (PSI). If there is an issue with AD1981AJST-REEL, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The AD1981AJST-REEL part is unused and in its original packaging.
Return procedure for AD1981AJST-REEL:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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