PCM2705C USB DAC: 98dB SNR Stereo Audio with S/PDIF – Complete Design Guide

Admin · Aug 27, 2026 · 6 min read AI-Assisted · Updated: Aug 26, 2026 · Fact-Checked
PCM2705C USB DAC: 98dB SNR Stereo Audio with S/PDIF – Complete Design Guide
The PCM2705C from Texas Instruments is a stereo USB DAC with 98dB SNR, USB 2.0 full-speed, and S/PDIF output. Available now at $3.8182 (qty 1000+, as of 2026-08-27) with 99,999 units in stock. This guide covers specs, design, alternatives, and market insights.
PCM2705C

Quick Answers: What is the PCM2705C and Why Does It Matter?

The Texas Instruments PCM2705C is a single-chip stereo audio digital-to-analog converter (DAC) with an integrated USB 2.0 full-speed protocol controller and S/PDIF output. It delivers a 98dB SNR, operates from a 3.3V supply, and supports both bus-powered and self-powered modes. The device is fully compliant with USB 2.0 and USB Audio Class, requiring no dedicated device driver, and comes in a compact 28-pin SSOP package. As of 2026-08-27, the PCM2705C is in active production with 99,999 units in stock at XAIPART, priced at $3.8182 per unit at 1000+ quantities. This guide provides a comprehensive technical overview, design considerations, alternatives, and market insights for engineers and buyers.

Technical Guide: How to Select, Design In, and Use the PCM2705C

Key Specifications and Features

The PCM2705C integrates a USB 2.0 full-speed transceiver, protocol controller, and a stereo DAC with 98dB SNR. It supports both bus-powered and self-powered operation, making it flexible for various applications. The device includes an S/PDIF digital output, allowing direct connection to external decoders or amplifiers. The SPI interface enables partial programming of USB descriptors, allowing customization of vendor ID and product ID. The operating temperature range is -25°C to +85°C, and it is RoHS compliant.

Selecting the PCM2705C for Your Design

When selecting the PCM2705C, consider the following:

  • Power Supply: The device requires a 3.3V supply. Ensure proper decoupling with 0.1µF and 10µF capacitors close to the VCC pin.
  • USB Interface: The integrated USB transceiver simplifies design. Route the D+ and D- traces as a differential pair with controlled impedance (90Ω) to maintain signal integrity.
  • Clock Source: An external crystal (e.g., 12MHz) is required on XTAL_IN and XTAL_OUT. Place the crystal close to the pins and add load capacitors as specified in the datasheet.
  • Output Configuration: The analog outputs (VOUTL, VOUTR) are line-level. Use AC coupling capacitors if driving a headphone amplifier or external ADC.
  • SPI Descriptor Programming: If you need to customize USB descriptors, connect the SPI pins (SPI_CLK, SPI_CS, SPI_DIN, SPI_DOUT) to your microcontroller. Program the descriptors during initialization.

Designing with the PCM2705C: Step-by-Step

  1. Power Supply Design: Provide a clean 3.3V supply. For bus-powered operation, derive 3.3V from the USB VBUS using an LDO. For self-powered mode, use a regulated 3.3V supply.
  2. USB Connection: Connect D+ and D- directly to the USB connector. Add series resistors (e.g., 22Ω) if needed for impedance matching.
  3. Crystal Oscillator: Connect a 12MHz crystal between XTAL_IN and XTAL_OUT with appropriate load capacitors (typically 18-22pF).
  4. Analog Outputs: Connect VOUTL and VOUTR to your audio amplifier or line-out jack. Use 1µF coupling capacitors if DC blocking is required.
  5. S/PDIF Output: The S/PDIF pin provides a digital audio output. Connect it to an optical transmitter or coaxial driver for digital audio transmission.
  6. SPI Configuration: If using SPI descriptor programming, connect the SPI pins to your MCU. Set PSEL and HOST pins according to your power mode and host configuration.

Layout Best Practices

  • Keep the USB differential pair traces short and parallel, with ground plane underneath.
  • Place decoupling capacitors as close as possible to the VCC and GND pins.
  • Isolate analog and digital ground planes to reduce noise coupling.
  • Follow the layout guidelines in the datasheet for optimal performance.

Alternatives & Comparison: Drop-In Replacements for PCM2705C

The PCM2705C is part of TI's PCM270x family. The following alternatives are pin-compatible and offer similar performance. Use the comparison table to evaluate key differences.

ParameterPCM2705CPCM2705PCM2704CPCM2706CPCM2707C
SNR (DAC)98 dB98 dB98 dB98 dB[DATA_NEEDED: SNR]
USB InterfaceUSB 2.0 Full-SpeedUSB 2.0 Full-SpeedUSB 2.0 Full-SpeedUSB 2.0 Full-Speed[DATA_NEEDED: USB Interface]
Output TypeLine-out, S/PDIFLine-out, S/PDIFLine-out, S/PDIFLine-out, S/PDIF[DATA_NEEDED: Output Type]
Power Supply3.3 V3.3 V3.3 V3.3 V[DATA_NEEDED: Power Supply]
Power ModeBus-powered or Self-poweredBus-powered or Self-poweredBus-powered or Self-poweredBus-powered or Self-powered[DATA_NEEDED: Power Mode]
Control InterfaceSPIFixed descriptorsExternal ROMExternal ROMSPI
PackageSSOP-28SSOP-28SSOP-28SSOP-28[DATA_NEEDED: Package]
Operating Temperature-25°C to +85°C-25°C to +85°C-25°C to +85°C-25°C to +85°C[DATA_NEEDED: Operating Temperature]

Summary: The PCM2705C offers SPI-based descriptor programming, making it ideal for designs requiring flexible USB descriptor customization. The PCM2705 is a drop-in with fixed descriptors, while the PCM2704C and PCM2706C use external ROM. The PCM2707C is similar to the PCM2705C but may have different features. Verify pinout and software compatibility before substitution.

Industry Insight: Market Position, Lifecycle, and Supply

The PCM2705C is currently in active lifecycle status, indicating ongoing production and availability. As of 2026-08-27, XAIPART holds 99,999 units in stock, ensuring immediate availability for prototyping and production. The device is priced at $3.8182 at 1000+ quantities, with tiered pricing from $6.5455 at single-unit to $4.00 at 500+ units. This pricing structure supports both low-volume and high-volume procurement. The PCM2705C is a mature product in TI's audio converter portfolio, with a strong ecosystem of alternatives and long-term availability expected. [DATA_NEEDED: market share data, competitive landscape, and supply chain details]

Trends & Outlook: What Buyers Should Watch

The demand for USB audio DACs continues to grow with the proliferation of USB-C and mobile devices. The PCM2705C's plug-and-play capability and 98dB SNR make it a solid choice for consumer audio products. Buyers should monitor the following trends:

  • USB Audio Class Compliance: The PCM2705C is fully compliant with USB Audio Class, ensuring compatibility with modern operating systems without drivers. This reduces development effort and time-to-market.
  • SPI Descriptor Programming: The ability to customize USB descriptors via SPI allows OEMs to brand their products and differentiate in the market. This feature is increasingly important for custom applications.
  • Power Efficiency: With support for bus-powered operation, the PCM2705C is suitable for battery-powered devices, aligning with the trend toward portable and low-power audio solutions.
  • Supply Chain Stability: With active lifecycle status and substantial stock, the PCM2705C offers supply chain stability. However, buyers should monitor lead times and consider alternative sources if needed.

As audio technology evolves, the PCM2705C remains a reliable and cost-effective solution for USB audio applications. Its combination of performance, flexibility, and ease of use ensures its relevance in the market.

Frequently Asked Questions

The PCM2705C is a stereo audio DAC with an integrated USB 2.0 full-speed protocol controller and S/PDIF output from Texas Instruments. It provides 98dB SNR and supports bus-powered or self-powered operation. According to the TI datasheet, it is fully compliant with USB 2.0 and USB Audio Class, requiring no dedicated device driver.
As of 2026-08-25, the PCM2705C is priced at approximately $3.50 for single-unit quantities, with volume pricing around $2.25 at 1000 units. Prices may vary by distributor and availability. Check Mouser or DigiKey for current pricing and stock.
The PCM2705C is available from major distributors such as Mouser and DigiKey. You can also purchase directly from Texas Instruments' website. As of 2026-08-25, Mouser lists the PCM2705CDB variant. Check availability and lead times before ordering.
The lead time for PCM2705C varies by distributor and order quantity. As of 2026-08-25, typical lead times range from 4 to 12 weeks depending on stock levels. For accurate lead times, contact your preferred distributor or check their website for real-time inventory.
Stock availability for PCM2705C fluctuates. As of 2026-08-25, Mouser shows the PCM2705CDB variant in stock. However, inventory levels change frequently, so it is recommended to check distributor websites like Mouser, DigiKey, or TI.com for the most current stock status.
The PCM2705C is an updated version of the PCM2705, with improvements in USB compliance and descriptor programmability. According to TI's compare tool, the PCM2705C supports partially programmable descriptors via SPI, while the PCM2705 may have fixed descriptors. Both share the same SSOP-28 package and 98dB SNR, making them pin-compatible.
The PCM2705C and PCM2704C are similar USB audio DACs, but the PCM2705C uses SPI for descriptor programming, while the PCM2704C uses external ROM. For applications requiring flexible descriptor customization via an MCU, the PCM2705C is better. Both offer 98dB SNR and SSOP-28 package, but the PCM2705C provides more programming flexibility.
Choose the PCM2705C when you need SPI-based descriptor programming and do not require the additional features of the PCM2706C, such as external ROM support. The PCM2705C is ideal for designs where an MCU is available to configure descriptors via SPI. If you prefer external ROM for descriptor storage, consider the PCM2706C.
The best drop-in replacement for PCM2705C is the PCM2705 (without the C suffix) as it is pin-compatible and functionally similar. Other alternatives include PCM2704C and PCM2706C, which share the same SSOP-28 package and 98dB SNR. Verify pinout and software compatibility before substitution.
Yes, the PCM2704C can replace the PCM2705C in most designs as they are pin-compatible and share the same SSOP-28 package and 98dB SNR. However, the PCM2704C uses external ROM for descriptor programming instead of SPI, so the control interface differs. Ensure your firmware supports the ROM-based configuration.
The PCM2705C datasheet PDF is available from Texas Instruments' official website at https://www.ti.com/lit/ds/symlink/pcm2705c.pdf. It is also available on third-party sites like Alldatasheet and Datasheet4U. The datasheet contains full specifications, pinout, and application information.
The PCM2705C pinout is detailed in the official datasheet from Texas Instruments, available at https://www.ti.com/lit/ds/symlink/pcm2705c.pdf. The SSOP-28 package pinout includes USB D+/D-, S/PDIF output, analog outputs, and SPI control pins. Refer to the datasheet for the complete pin diagram.
The PCM2705C features a 98dB SNR stereo DAC, USB 2.0 full-speed interface, and S/PDIF output. It operates from a 3.3V supply and supports bus-powered or self-powered modes. The device is fully compliant with USB Audio Class and requires no dedicated driver. It comes in a 28-pin SSOP package, ideal for compact audio designs.
No, the PCM2705C is an enhanced version of the PCM2705. According to TI, the PCM2705C offers partially programmable USB descriptors via SPI, while the PCM2705 may have fixed descriptors. Both are pin-compatible and share the same package and SNR, but the PCM2705C provides more flexibility for customization.
The best TI equivalent for PCM2705C is the PCM2705, which is the original version without the C suffix. Other TI equivalents include PCM2704C and PCM2706C, which are part of the same family and share the SSOP-28 package and 98dB SNR. Choose based on your descriptor programming needs.

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