Texas Instruments PCM2904DBG4

Overview

PCM2904DBG4 from Texas Instruments is a single-chip USB 1.1-compliant stereo audio codec with integrated full-speed USB transceiver, 16-bit delta-sigma ADC/DAC, and SpAct™ clock recovery architecture. It delivers THD+N = 0.01% (ADC) and 0.005% (DAC), supports sampling rates up to 48 kHz for playback and 44.1 kHz for recording, and operates from a single 5-V bus power supply. It is used in USB audio speaker systems requiring low-jitter, plug-and-play stereo audio conversion without host-side firmware.

For engineers reviewing the PCM2904DBG4 datasheet, PCM2904DBG4 pinout, PCM2904DBG4 application, or PCM2904DBG4 equivalent, key selection criteria include its USB adaptive playback / asynchronous record mode support, absence of S/PDIF interface (distinguishing it from PCM2906), 28-pin SSOP package compatibility, and HID volume/mute control capability via dedicated GPIO pins.

Technical Context

The PCM2904DBG4 implements TI's SpAct™ architecture to recover audio clocks directly from USB packet timing, enabling independent playback and record sampling rates with low jitter-no external crystal oscillator required beyond the 12-MHz reference. Its analog front-end integrates antialiasing (ADC) and low-pass (DAC) filters, plus on-chip decimation/interpolation digital filters with ±0.05 dB pass-band ripple and –65 dB stop-band attenuation.

It uses a fully hardware-based USB protocol controller compliant with USB Audio Class 1.0 and HID specifications, supporting four USB interfaces: control (IF #0), isochronous-out streaming (IF #1), isochronous-in streaming (IF #2), and HID (IF #3). The device operates in bus-powered mode only and includes suspend flag (SSPND) and test pins (TEST0/TEST1) for production validation.

Key Specifications

Pinout & Package

PCM2904DBG4 is housed in a 28-pin SSOP (Shrink Small Outline Package) with 0.65-mm lead pitch, optimized for compact USB audio peripheral designs. Pin functions are electrically validated per TI SLES042C datasheet Rev. November 2007.

Key Features

Applications

Equivalent & Alternatives

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

Compared with PCM2906DBR, PCM2904DBG4 removes S/PDIF circuitry to reduce power and cost while retaining identical analog performance and USB interface behavior; compared with CY7C68013A-56PVXC, PCM2904DBG4 provides turnkey audio conversion without firmware development or external analog components.

Availability

PCM2904DBG4 is available at Aetrix Electronics and suitable for USB audio speaker, USB headset, and USB monitor audio applications requiring stable component supply, long-term industrial availability, and RoHS-compliant packaging.

Supply support for PCM2904DBG4 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and connectivity technologies, with decades of expertise in high-fidelity audio signal chain design.

The PCM2904DBG4 belongs to TI's Burr-Brown audio codec product line, engineered specifically for cost-sensitive, plug-and-play USB audio peripherals requiring minimal external components and zero-host-driver deployment.

FAQ

What is the primary function of the PCM2904DBG4 in a USB audio system?

The PCM2904DBG4 serves as a complete stereo USB audio codec, performing bidirectional analog-to-digital (ADC) and digital-to-analog (DAC) conversion while managing USB 1.1 full-speed communication, clock recovery via SpAct™, and HID volume/mute control-all within a single 28-pin SSOP package. It eliminates the need for external microcontrollers or audio clock generators in basic USB speaker/headset designs.

Does the PCM2904DBG4 require an external crystal oscillator?

Yes-the PCM2904DBG4 requires a 12-MHz fundamental-mode crystal connected between XTI (pin 21) and XTO (pin 20) to enable its SpAct™ clock recovery architecture. This crystal provides the reference for generating low-jitter audio sampling clocks (e.g., 44.1 kHz or 48 kHz) directly from USB packet timing, without a separate PLL.

How does the PCM2904DBG4 handle USB suspend mode?

The PCM2904DBG4 asserts SSPND (pin 28) low during USB suspend to signal system power management circuits. In this state, supply current drops to 210 µA while preserving configuration; the device automatically resumes full operation upon USB resume signaling. No firmware or host interaction is required for suspend/resume transitions.

Can the PCM2904DBG4 support microphone input and headphone output simultaneously?

Yes-the PCM2904DBG4 supports full-duplex operation: its stereo ADC accepts simultaneous left/right analog inputs (e.g., stereo mic or line-in), while its stereo DAC drives headphone or speaker outputs. Sampling rates are independently configurable-e.g., 44.1 kHz ADC (asynchronous) and 48 kHz DAC (adaptive)-enabling real-time voice communication applications.

What distinguishes the PCM2904DBG4 from the PCM2906DBR?

The PCM2904DBG4 lacks S/PDIF interface circuitry present in the PCM2906DBR (pins DIN/DOUT), making it simpler and lower-cost for pure USB analog audio applications. Both share identical pinout, USB architecture, ADC/DAC performance, and SpAct™ clock recovery-but only PCM2906DBR supports optical digital audio I/O.