AD1981AJST

Overview

The AD1981AJST is a stereo AC '97 compliant audio codec manufactured by Analog Devices Inc. It features a 20-bit DAC and a 16-bit ADC, supporting variable sample rates from 7040 Hz to 48 kHz with 1 Hz resolution. The device includes an integrated stereo headphone amplifier, S/PDIF output, and multiple analog inputs including LINE-IN, AUX, CD, PHONE_IN, and MIC_IN. It operates on split power supplies of 3.3 V digital and 5 V analog, consuming 555 mW in full active mode. The component is housed in a 48-lead LQFP package.

Feature Summary

• Supports full-duplex variable sample rates from 7040 Hz to 48 kHz with 1 Hz resolution.
• Includes built-in digital equalizer function for optimized speaker sound.
• Features jack sense pins that provide automatic output switching between line-out and headphones.
• Provides external audio power-down control via the EAPD pin.

Applications

• AC '97 compliant motherboard audio systems
• Integrated PC sound cards
• Multimedia desktop computers

Procurement Notes

Verify the specific ordering suffix JST corresponds to the ST-48 Thin Quad Flatpack package option. Confirm the operating temperature range matches the 0 °C to 70°C specification required for your application environment before finalizing procurement.

Selection Notes

Select this component when an AC '97 interface is required alongside an integrated headphone amplifier and S/PDIF output. Ensure the system design accommodates the split 3.3 V digital and 5 V analog power supply requirements and provides a 24.576 MHz crystal input clock.

Part Context

This part belongs to the AD1981A series of AC '97 codecs. It is designed as a complete audio solution for PC platforms, combining high-resolution conversion with analog mixing and amplification capabilities within a single integrated circuit package.

Replacement Considerations

Consult official documentation for verified substitutes. Cross-reference pinouts and AC '97 register compatibility if replacing with other Analog Devices or third-party AC '97 codecs.

FAQ

What is the maximum attenuation range for the volume controls?

The master volume, headphone volume, mono volume, and input attenuators all support a maximum attenuation range of 46.5 dB with a step size of 1.5 dB.

How does the device handle microphone bias?

The AD1981A provides a programmable VREFOUT output capable of driving up to 5 mA, which is intended for microphone bias and external power amplifier bias.

What is the dynamic range of the DAC?

The Digital-to-Analog Converter (DAC) offers a dynamic range of 90 dB under standard test conditions (-60 dB input THD+N referenced to full scale, A-weighted).