Analog Devices Inc. AD1838AS

Overview

AD1838AS from Analog Devices is a 24-bit, 96 kHz stereo audio codec with three independent stereo DACs (6 channels) and one stereo ADC (2 channels), operating from dual 5 V analog/digital supplies and featuring 3.3 V–tolerant digital I/O. It delivers –95 dB THD+N and 105–108 dB SNR across ADC/DAC paths, supports I²S/right-justified/left-justified/DSP serial formats, and targets high-fidelity consumer audio systems requiring multi-channel playback and recording.

For engineers reviewing the AD1838AS datasheet, AD1838AS pinout, AD1838AS application, or AD1838AS equivalent, this page provides verified functional identity, validated 52-lead MQFP package mapping, confirmed differential analog I/O architecture, real-world timing interface modes (including TDM256 and packed 256), and two rigorously cross-checked alternative codecs for system-level audio I/O substitution.

Technical Context

The AD1838AS integrates three independent 24-bit stereo DAC engines-each with multibit ΣΔ modulation, digital interpolation filtering (passband ripple ±0.01 dB), and 1024-step linear volume control-and one 24-bit stereo ADC with decimation filters offering 120 dB stop-band attenuation and group delay of 460 µs at 96 kHz. All converters share a programmable MCLK scaler supporting 48/96/192 kHz sample rates, with DAC1 uniquely capable of 192 kHz operation.

Its flexible serial architecture includes three dedicated DAC data inputs (DSDATA1–3), one ADC output (ASDATA), SPI-compatible control port (CIN/CCLK/CLATCH/COUT), and auxiliary TDM mode enabling 8-in/8-out expansion via SHARC SPORT interface. The device implements differential analog I/O (±1.4 V swing around 2.25 V VREF), on-chip reference, and dual power domains (AVDD/DVDD/ODVDD) with separate analog/digital ground planes.

Key Specifications

Pinout & Package

AD1838AS is housed in a 52-lead MQFP (S-52) package with exposed thermal pad, specified for industrial temperature operation (–40°C to +85°C). Pin layout follows standard top-view orientation with AGND/DGND separation, dedicated analog/digital supply pins (AVDD/DVDD/ODVDD), and fully differential analog I/O grouped by channel.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar audio codec applications.

Compared with AK4358VN and CS42526-CQZ, the AD1838AS uniquely combines triple stereo DACs with TDM256 + packed 256 modes, enabling both 8-in/8-out expansion and consolidated 6-channel DAC control - a capability absent in either alternative.

Availability

AD1838AS is available at Aetrix Electronics and suitable for DVD players, home theater receivers, and automotive infotainment systems requiring stable component supply, long-term lifecycle support, and guaranteed industrial-temperature operation.

Supply support for AD1838AS 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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA, with design centers worldwide.

The AD1838AS belongs to Analog Devices' high-fidelity audio codec product line, engineered for multi-channel consumer and professional audio systems demanding low THD+N, wide dynamic range, and flexible digital interface scalability.

FAQ

What is the maximum sample rate supported by the AD1838AS ADC and DAC sections?

The AD1838AS ADC supports up to 96 kHz sample rate. Its DAC section supports 48 kHz, 96 kHz, and 192 kHz - but only DAC1 (first stereo pair) operates at 192 kHz; DAC2 and DAC3 are limited to 96 kHz. This asymmetric capability enables high-resolution monitoring on DAC1 while maintaining legacy compatibility on other channels. The AD1838AS uses internal clock scaling to derive these rates from MCLK inputs of 12.288 MHz, 24.576 MHz, or 49.152 MHz.

Does the AD1838AS support I²S interface, and how is it configured by default?

Yes, the AD1838AS supports I²S interface on both ADC and DAC serial ports, and it defaults to I²S mode upon power-up. The ADC output (ASDATA) and DAC inputs (DSDATA1–3) are I²S-aligned with data delayed by one BCLK after LRCLK edge. Configuration is changed via SPI registers: ADC Control Register 2 (Bits 6–8) and DAC Control Register 1 (Bits 5–7). The AD1838AS also supports right-justified, left-justified, DSP, TDM256, and packed 256 modes without hardware modification.

How does the AD1838AS handle power supply separation and noise isolation?

The AD1838AS employs strict power domain separation: AVDD (analog), DVDD (digital core), and ODVDD (3.3 V–tolerant I/O driver) are independently routed with dedicated AGND and DGND planes. Each supply requires local 100 nF ceramic + 22 µF bulk capacitance. FILTD and FILTR pins demand 10 µF/100 nF parallel bypassing to suppress DAC bias noise and stabilize the 2.25 V reference. PSRR is –75 dB at 20 kHz, confirming effective analog supply rejection - a key design value for noisy automotive or industrial environments where the AD1838AS is deployed.

What is the purpose of the TDM256 mode in the AD1838AS, and which pins are repurposed?

TDM256 mode enables 8-in/8-out audio I/O expansion by repurposing pins including ASDATA (as TDM output to SHARC), DSDATA1 (as TDM input from SHARC), ALRCLK (as FSTDM frame sync), ABCLK (as TDM BCLK), and DLRCLK/DBCLK (as AUXLRCLK/AUXBCLK). This mode allows glueless connection to a single SHARC SPORT, eliminating external multiplexers. The AD1838AS becomes a scalable audio hub - critical in digital mixing consoles or broadcast processors where the AD1838AS serves as the central I/O bridge between DSP and analog stages.

Can the AD1838AS operate with a single 5 V supply, and what are the implications for digital I/O voltage levels?

Yes, the AD1838AS can operate with a single 5 V supply applied to both AVDD and DVDD, but ODVDD must still be supplied at 3.0–5.0 V to ensure correct digital I/O voltage levels. When ODVDD = 3.3 V, the digital interface (CIN, CCLK, CLATCH, COUT, DSDATAx, ASDATA, etc.) is 3.3 V–tolerant - allowing direct connection to 3.3 V logic without level shifters. This dual-supply flexibility makes the AD1838AS compatible with mixed-voltage systems, a key advantage in modern embedded audio designs where the AD1838AS interfaces with both 5 V analog circuitry and 3.3 V digital controllers.