Analog Devices Inc. AD1837AS

Overview

AD1837AS from Analog Devices is a 24-bit, 96 kHz stereo audio codec with four independent stereo DACs (8 channels) and one stereo ADC (2 channels), operating from dual 5 V analog/digital supplies and supporting 3.3 V–tolerant digital I/O. It delivers –95 dB THD+N (ADC) and –92 dB THD+N (DAC), 105 dB SNR (ADC), 108 dB SNR (DAC), and on-chip 1024-step volume control per channel. It is used in multichannel home theater receivers requiring high-fidelity, low-jitter audio conversion and flexible TDM/I2S interfacing.

For engineers reviewing the AD1837AS datasheet, AD1837AS pinout, AD1837AS application, or AD1837AS equivalent, this page provides verified functional identity, validated 52-lead MQFP package mapping, confirmed 8-DAC/2-ADC architecture, real-world timing interface modes (I2S, TDM256, packed 256), and two manufacturer-validated alternative codecs for multichannel audio system design.

Technical Context

The AD1837AS integrates eight independent DAC channels-four stereo pairs-with individual 1024-step linear volume controls, clickless mute, and data-directed scrambling to minimize jitter sensitivity. Its ADC section comprises two fully differential 24-bit channels with 120 dB stop-band attenuation decimation filters and programmable master/slave clocking.

It supports three distinct serial interface configurations: standard I2S/right-/left-justified/DSP modes for discrete channel access; packed 256-mode TDM for 8-in/8-out operation using single DSDATA1/ASDATA lines; and auxiliary TDM mode enabling glueless connection to SHARC® SPORT with redefined pin functions including FSTDM/BCLK outputs and AAUXDATA inputs.

Key Specifications

Pinout & Package

AD1837AS is housed in a 52-lead MQFP (S-52A) package with exposed paddle, specified for industrial temperature range (–40°C to +85°C). Pin 1 is located at top-left corner (notch-marked side), with pins numbered counter-clockwise. AGND (pins 1, 39), DGND (pins 40, 52), and AVDD (pins 11, 19, 29) are distributed for analog/digital ground and supply separation to minimize coupling.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AK4118VN and CS42888-CQZ, the AD1837AS uniquely combines 5 V operation with 3.3 V–tolerant I/O, industrial temperature range, and native TDM256 support - making it the only option qualified for drop-in replacement in existing SHARC-based AV receivers requiring 8-channel output and backward-compatible power architecture.

Availability

AD1837AS is available at Aetrix Electronics and suitable for home theater receivers, automotive infotainment head units, and professional audio effects processors requiring stable component supply across extended product lifecycles and industrial temperature operation.

Supply support for AD1837AS 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 leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA, with R&D and manufacturing facilities worldwide.

The AD1837AS belongs to Analog Devices' high-fidelity audio codec product line, designed specifically for multichannel consumer and professional audio systems demanding low THD+N, flexible digital interface options, and robust industrial-grade reliability.

FAQ

What is the maximum sample rate supported by the AD1837AS ADC and DAC sections?

The AD1837AS ADC supports up to 96 kHz sample rate across both channels. The DAC section supports up to 192 kHz - but only on DAC1 (OUTL1/OUTR1); DAC2–DAC4 are limited to 96 kHz. This asymmetry enables high-fidelity front-channel playback while maintaining phase-aligned surround output. The AD1837AS achieves this via internal clock scaling and stereo replicate functionality, allowing DAC1's 192 kHz stream to be copied to other DACs when needed.

Does the AD1837AS support I2S, TDM, and packed data modes simultaneously?

No - the AD1837AS supports only one primary serial data mode at a time, selected via SPI register configuration. I2S is the default for both ADC and DAC ports. Packed 256 mode is mutually exclusive and requires M/S = 0 (ADC master) and 48 kHz operation. Auxiliary TDM mode redefines multiple pins (e.g., DSDATA2–4 become AAUXDATA1–3) and cannot coexist with standard I2S. The AD1837AS must be configured in a single operational mode per power cycle.

How does the AD1837AS handle power supply separation between analog and digital domains?

The AD1837AS uses physically separate AVDD (analog) and DVDD/ODVDD (digital) supply pins, with dedicated AGND and DGND networks. AVDD and DVDD are both rated for 4.5–5.5 V, while ODVDD accepts 3.0–DVDD V to support 3.3 V–tolerant digital interfaces. Bypassing requires 100 nF ceramic capacitors near each supply pin plus ≥22 µF bulk capacitance. For optimal performance, Analog Devices recommends ferrite-bead isolation between analog and digital supplies when shared rails are unavoidable - a design requirement explicitly validated for the AD1837AS.

Can the AD1837AS operate with a 12.288 MHz master clock for CD-quality (44.1 kHz) audio?

Yes - the AD1837AS MCLK scaler supports programmable division ratios (1×, 2×, or 2/3×) to derive target sample rates from non-standard MCLK frequencies. While 12.288 MHz yields 48 kHz by default (2× scaling), a 11.2896 MHz MCLK is recommended for exact 44.1 kHz operation. The AD1837AS datasheet confirms this flexibility, and the internal IMCLK generator maintains 24.576 MHz regardless of input MCLK, ensuring consistent modulator performance across all supported sample rates.

What is the function of the FILTD and FILTR pins on the AD1837AS?

FILTD connects to an external capacitor (recommended 10 µF/100 nF) that filters noise from the internal DAC bias circuitry, directly reducing DAC output noise floor. FILTR connects to the same capacitor network and provides access to the internal 2.25 V reference voltage, which can bias external op-amps to match the AD1837AS's analog I/O common-mode level. Both pins are critical for achieving the specified –92 dB THD+N and 108 dB SNR; omitting these capacitors degrades measured performance as documented in the AD1837AS datasheet.