AD1938WBSTZ-RL

Overview

The AD1938WBSTZ-RL is a high-performance, single-chip audio codec manufactured by Analog Devices Inc. It integrates four analog-to-digital converters (ADCs) with differential inputs and eight digital-to-analog converters (DACs) with single-ended outputs. The device utilizes a multibit sigma-delta architecture and operates from a single 3.3 V supply. It supports sample rates from 8 kHz to 192 kHz with 24-bit resolution. Key electrical specifications include a DAC dynamic range of 108 dB and an ADC dynamic range of 107 dB. The component features an on-chip PLL for clock generation, SPI control interface, and is housed in a 48-lead LQFP package.

Feature Summary

• Integrates four differential ADC channels and eight single-ended DAC channels within a single chip.
• Features low EMI design utilizing continuous time architectures and internal PLL clock generation.
• Includes software-controllable clickless mute, log volume control with autoramp, and power-down modes.
• Supports multiple data formats including right-justified, left-justified, I2S, and TDM modes.

Applications

• Automotive audio systems
• Home theater systems
• Set-top boxes
• Digital audio effects processors

Procurement Notes

Verify the specific ordering suffix WBSTZ-RL against the manufacturer's current datasheet to confirm package type and tape-and-reel packaging status. Ensure that the automotive qualification requirements match the project specifications, as this variant is designated for such applications. Cross-reference the pinout diagram with the PCB layout to ensure compatibility with the 48-lead LQFP footprint.

Selection Notes

Select this component when a high channel count with mixed input/output configurations is required. The AD1938 provides four differential ADCs suitable for microphone preamplifier interfaces and eight single-ended DACs for driving line-level outputs. Consider the 3.3 V supply constraint and the availability of an SPI interface for system configuration. Evaluate the thermal performance within the 48-lead LQFP package if operating at maximum sample rates.

Part Context

This part belongs to the AD193x family of audio codecs from Analog Devices. While other members like the AD1939 offer higher channel counts or differential DAC outputs, the AD1938 specifically targets applications requiring four stereo ADC inputs and eight stereo DAC outputs. It shares the same core sigma-delta architecture and low EMI design philosophy found across the series.

Replacement Considerations

The AD1939WBSTZ-RL is listed as a direct substitute in distributor databases. Verify functional equivalence regarding the number of channels and output types before replacement, as the AD1939 may feature differential DAC outputs instead of single-ended ones.

FAQ

How does the AD1938 generate its master clock?

The device uses an on-chip phase-locked loop (PLL) to derive the master clock from the LR clock or an external crystal connected to the MCLKI/XI pin, eliminating the need for a separate high-frequency master clock source.

What is the function of the CM pin?

The CM pin provides a common-mode reference voltage of 1.5 V, which can be used to bias external operational amplifiers that buffer the differential ADC input signals or the single-ended DAC output signals.

Can the AD1938 operate without a microcontroller?

Yes, it supports a standalone mode configured via the serial control pins at reset. However, this mode is limited to stereo operation with an I2S data format and a fixed 256 fS master clock rate.