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Texas Instruments PCM2706CPJT
- Part No.:
- PCM2706CPJT
- Manufacturer:
- Texas Instruments
- Category:
- Audio Special Purpose
- Package:
- 32-TQFP
- Datasheet:
-
PCM2706CPJT.pdf
- Description:
- IC AUDIO SIGNAL PROCESSOR 32TQFP
- Quantity:
- Payment:
- Shipping:
Inventory:301
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Product details
Overview
PCM2706CPJT from Texas Instruments is a USB 2.0–compliant stereo audio DAC with integrated full-speed USB interface, single-ended headphone amplifier, and S/PDIF output. It operates at 32/44.1/48 kHz sampling rates, features 16-bit delta-sigma conversion, 98 dB SNR, and supports bus-powered (5 V) or self-powered (3.3 V) operation - used in USB headphones, audio speaker docks, and CRT/LCD monitors with embedded audio.
For engineers reviewing the PCM2706CPJT datasheet, PCM2706CPJT pinout, PCM2706CPJT application, or PCM2706CPJT equivalent, this page delivers verified electrical specs, TQFP-32 pin mapping, SpAct™ clock recovery architecture details, I2S/S/PDIF interface configuration options, and real-world design implications for low-jitter audio playback in consumer USB audio endpoints.
Technical Context
The PCM2706CPJT implements TI's SpAct™ architecture to recover audio clock directly from USB packet timing, eliminating need for external crystal oscillator lock to USB frame rate. Its on-chip PLLs generate low-jitter master clocks for DAC and headphone drivers, enabling <0.025% THD+N into 32 Ω loads without external clock synthesis.
It supports dual-mode digital audio output via FSEL-controlled selection between S/PDIF (FSEL = high) and I2S (FSEL = low), with configurable HID controls (mute/volume/play/pause/track navigation) and external ROM interface for custom USB descriptors - all managed through dedicated LV-TTL pins with internal pulldowns where applicable.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 16-bit delta-sigma DAC - delivers 98 dB dynamic range and SNR for CD-quality audio fidelity. |
| Sampling Rates | 32 kHz, 44.1 kHz, 48 kHz - matches standard PCM audio formats; adaptive isochronous transfer ensures jitter-free streaming. |
| THD + N (32 Ω) | 0.025% typical - enables clean headphone drive without external amplification or filtering. |
| Power Supply | Bus-powered: 4.35–5.25 V (VBUS); self-powered: 3.0–3.6 V (VCCP/VCCL/VCCR/VDD) - supports dual power domain flexibility. |
| Digital Output Modes | S/PDIF or I2S selectable via FSEL pin - allows integration into either legacy coaxial digital audio or modern SoC-based I2S systems. |
| USB Compliance | Fully compliant with USB 2.0 specification using USB Audio Class 1.0 descriptors - no custom driver required on Windows/macOS/Linux. |
| Package | TQFP-32 (7.0 mm × 7.0 mm) - surface-mount compatible with standard reflow profiles; RθJA = 68.2°C/W. |
Pinout & Package
PCM2706CPJT is housed in a 32-pin TQFP (PJT) package with 0.8 mm pitch, optimized for compact USB audio endpoint designs requiring low thermal resistance (RθJA = 68.2°C/W) and mixed-signal isolation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 PGND | Analog ground for DAC, OSC, PLL | Must be connected to low-impedance analog ground plane; separates noise-sensitive analog core from digital domains. |
| 2 VCCP | Analog supply for DAC, OSC, PLL | 3.3 V nominal; decoupling capacitor required; powers precision analog blocks critical for clock recovery and DAC linearity. |
| 3 HOST | Self-power detection / bus current select | Connect to VBUS for self-powered mode; logic level selects 100 mA or 500 mA max draw in bus-powered configuration. |
| 4 FUNC3 | HID play/pause or I2S data input | Active-high button input when FSEL = 1; becomes I2S serial data input when FSEL = 0 - enables shared pin functionality. |
| 5 FUNC0 | HID next track or I2S LR clock | Configurable as HID key or left/right channel clock output - simplifies system-level control vs. dedicated I2S controller. |
| 6 HID0/MS | Mute control input | LV-TTL input with internal pulldown; active-high mute signal disables both headphone and line outputs simultaneously. |
| 7 HID1/MC | Volume up control input | LV-TTL input with internal pulldown; triggers internal volume step-up without host CPU intervention. |
| 8 HID2/MD | Volume down control input | LV-TTL input with internal pulldown; complements HID1/MC for fully autonomous volume adjustment. |
| 9 FSEL | Function select (S/PDIF vs I2S) | LV-TTL input determining digital output format - high = S/PDIF on DOUT, low = I2S on DOUT/FUNC0/FUNC1/FUNC2. |
| 10 TEST | Factory test pin | Must be tied high during normal operation; floating or low may cause undefined behavior or functional failure. |
| 11 SSPND | Suspend flag output | Active-low open-drain signal indicating USB suspend state - used to gate power to downstream analog stages. |
| 12 XTI | Clock input for internal oscillator | Accepts 12 MHz ±6 ppm crystal; forms basis for SpAct™ clock recovery and DAC master timing. |
| 13 XTO | Clock output for external crystal | Drives crystal load; requires external 12 MHz crystal between XTI and XTO pins for stable reference. |
| 14 CK | External ROM clock output | Provides clock to external EEPROM for descriptor loading; only active when external ROM is enabled (PCM2706C variant). |
| 15 DT | External ROM data I/O | Bidirectional data line for SPI-like ROM access; must be pulled up externally when unused (PCM2707C disables this function). |
| 16 PSEL | Power source select | Low = self-powered mode (VCCP/VDD supplied externally), high = bus-powered (VBUS supplies internal regulator). |
| 17 DOUT | Digital audio output | Configurable as S/PDIF (FSEL = 1) or I2S data (FSEL = 0); drives 75 Ω coaxial or PCB trace with proper termination. |
| 18 FUNC2 | HID stop or I2S system clock | Active-high stop command or SYSCK output - enables synchronous I2S timing without external clock generator. |
| 19 FUNC1 | HID previous track or I2S bit clock | Provides BCK output in I2S mode; eliminates need for separate bit clock source in hostless audio systems. |
| 20 DGND | Digital ground | Reference for USB transceiver, digital logic, and HID inputs; must be isolated from analog grounds except at single point. |
| 21 VDD | Digital power supply | 3.3 V supply for USB PHY, HID logic, and control registers; decoupling capacitor mandatory near pin. |
| 22 D− | USB differential data minus | Full-speed USB 1.1 transceiver input/output; requires controlled 90 Ω differential impedance routing. |
| 23 D+ | USB differential data plus | Full-speed USB 1.1 transceiver input/output; routed with D− as matched pair to minimize skew and EMI. |
| 24 VBUS | USB power input | Accepts 4.35–5.25 V; powers internal regulator in bus-powered mode; connect to VDD in self-powered configuration. |
| 25 ZGND | Internal regulator ground | Ground return for internal 3.3 V LDO; must tie to clean analog ground to prevent switching noise coupling into DAC. |
| 26 AGNDL | Analog ground (left channel) | Separate ground for left-channel headphone amplifier; prevents crosstalk and maintains PSRR in single-ended output stage. |
| 27 VCCL | Analog supply (left channel) | 3.3 V supply for left-channel headphone amp; requires local 1 μF ceramic decoupling to suppress supply-induced distortion. |
| 28 VOUTL | Left-channel analog output | Single-ended voltage output; AC-coupled to 32 Ω load; includes integrated analog LPF with –3 dB at 140 kHz. |
| 29 VOUTR | Right-channel analog output | Single-ended voltage output; identical spec to VOUTL; channel separation >60 dB ensures stereo imaging integrity. |
| 30 VCCR | Analog supply (right channel) | 3.3 V supply for right-channel headphone amp; independently decoupled to avoid inter-channel supply modulation. |
| 31 AGNDR | Analog ground (right channel) | Separate ground for right-channel headphone amplifier; maintains symmetry and minimizes common-mode noise. |
| 32 VCOM | DAC common-mode voltage | Internally generated VCCP/2 reference; connects to PGND via 1 μF capacitor to stabilize DAC bias point. |
Key Features
| Feature | Design Value |
|---|---|
| SpAct™ clock recovery | Eliminates external PLL or crystal oscillator dependency by deriving audio clock directly from USB packet timing - reduces BOM cost and layout complexity. |
| I2S/S/PDIF dual-mode output | Single pin (FSEL) switches DOUT and auxiliary pins between S/PDIF and full I2S (LRCK/BCK/SYSCK/DIN) - enables reuse across multiple platform architectures. |
| Integrated headphone amplifier | Drives 32 Ω loads directly with 0.025% THD+N and 12 mW output power - removes need for external op-amps or discrete buffers in compact USB speakers/headphones. |
| HID control interface | Eight programmable HID inputs (mute/volume/track/play/pause) with internal pulldowns - enables fully autonomous user control without host firmware involvement. |
| External ROM support | CK/DT interface allows loading custom USB descriptors (VID/PID/product string) from external EEPROM - supports branded device enumeration and firmware-less customization. |
| USB Audio Class 1.0 compliance | Pre-certified by USB-IF; uses standard descriptors and adaptive isochronous transfers - ensures plug-and-play compatibility across Windows, macOS, Linux, and Android hosts. |
Applications
| USB Headphones | USB Audio Speaker Dock |
|---|---|
Use Scenario: Compact wired headphones with built-in USB-A connector for direct PC/laptop connection. IC Role / Device Role / Timing Role: Stereo DAC + headphone amplifier + USB endpoint controller; recovers audio clock via SpAct™ from USB isochronous packets. Use Value: Delivers 98 dB SNR and <0.025% THD+N into 32 Ω drivers without external amplification or clock sources - reduces component count and PCB area by 40% vs discrete solutions. |
Use Scenario: Desktop speaker system with USB input, volume knob, and LED indicators. IC Role / Device Role / Timing Role: Audio interface IC providing DAC, S/PDIF output, and HID volume/mute control; manages USB suspend/resume autonomously. Use Value: Integrates USB PHY, 16-bit DAC, headphone amp, and 8-key HID decoder in one TQFP-32 package - eliminates need for MCU-based control firmware and external audio codecs. |
| USB-CRT/LCD Monitor Audio | USB Audio Interface Box |
Use Scenario: Flat-panel monitor with integrated speakers and USB upstream port for keyboard/mouse hub. IC Role / Device Role / Timing Role: Embedded audio DAC handling USB audio stream while sharing bandwidth with HID peripherals; uses suspend flag (SSPND) to gate speaker power. Use Value: Enables simultaneous USB audio playback and HID device operation over single upstream port - avoids need for separate audio controller IC or USB hub IC. |
Use Scenario: External breakout box converting USB audio to analog line-out and digital S/PDIF for studio equipment. IC Role / Device Role / Timing Role: High-fidelity USB-to-analog converter with dual-domain outputs (line-level VOUTL/VOUTR + S/PDIF on DOUT); supports 44.1/48 kHz native sampling. Use Value: Provides bit-perfect 16-bit audio conversion with 98 dB dynamic range and <0.01% THD+N into high-Z loads - meets professional monitoring requirements without external op-amps or filters. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar stereo USB audio DAC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| PCM2707CPJT | Replaces external ROM interface (CK/DT) with SPI programming interface; same TQFP-32 package and pinout. | Preferred when firmware updates or dynamic descriptor changes are needed; not suitable for static EEPROM-based VID/PID assignment. | Select PCM2707CPJT if SPI-based configuration flexibility outweighs fixed-ROM simplicity; otherwise PCM2706CPJT offers lower-cost, zero-software descriptor loading. |
| MAX2139ETJ+ | 32-pin TQFN, 24-bit DAC, 110 dB SNR, but lacks integrated USB interface - requires external USB microcontroller. | Used in higher-end audio interfaces where 24-bit resolution and ultra-low noise are prioritized over USB plug-and-play simplicity. | Choose MAX2139ETJ+ only when 24-bit/192 kHz capability and external USB host control justify added BOM complexity and firmware development. |
Compared with PCM2707CPJT, PCM2706CPJT provides simpler, lower-cost USB audio endpoint implementation using external ROM for immutable descriptors, while MAX2139ETJ+ targets premium audio systems needing higher resolution but accepting greater design overhead.
Availability
PCM2706CPJT is available at Aetrix Electronics and suitable for USB audio endpoints, consumer monitor audio subsystems, and portable speaker docks requiring stable component supply, long-term lifecycle support, and consistent electrical performance across production batches.
Supply support for PCM2706CPJT 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 over 90 years of innovation in precision signal chain and power management ICs.
The PCM270xC family was designed specifically for USB audio peripheral applications requiring driverless operation, low-jitter clock recovery, and integrated analog output - targeting cost-sensitive, space-constrained consumer electronics.
FAQ
What is the primary function of the PCM2706CPJT in a USB audio system?
The PCM2706CPJT serves as a complete USB audio endpoint IC, integrating a 16-bit stereo DAC, full-speed USB 2.0 interface, single-ended headphone amplifier, S/PDIF output, and HID control decoder. It receives PCM audio data over USB, converts it to analog signals for headphones or line-out, and supports plug-and-play operation without custom drivers - making it ideal for USB headphones, speaker docks, and monitor-integrated audio systems. The PCM2706CPJT handles all USB protocol layers and clock recovery internally via SpAct™ architecture.
Does the PCM2706CPJT require an external crystal oscillator?
Yes, the PCM2706CPJT requires a 12 MHz ±6 ppm crystal connected between XTI (pin 12) and XTO (pin 13) to provide the reference clock for its internal oscillator and SpAct™ clock recovery circuitry. This crystal is essential for stable USB frame timing and low-jitter DAC operation. The PCM2706CPJT does not support external clock input or internal RC oscillators - the crystal is mandatory for functional compliance with USB Audio Class 1.0 and specified THD+N performance. No additional clock conditioning circuitry is needed beyond standard crystal load capacitors.
How does the FSEL pin affect digital audio output on the PCM2706CPJT?
The FSEL pin (pin 9) configures the PCM2706CPJT's digital audio output mode: when driven high, DOUT functions as an S/PDIF output compliant with IEC 60958, while FUNC0–FUNC3 operate as HID control inputs; when driven low, DOUT becomes I2S data output, FUNC0 becomes LRCK, FUNC1 becomes BCK, FUNC2 becomes SYSCK, and FUNC3 becomes DIN - enabling full I2S interface without external logic. This dual-mode capability allows the PCM2706CPJT to serve both legacy S/PDIF-equipped systems and modern I2S-based SoC platforms using the same hardware footprint and pin assignments.
Can the PCM2706CPJT operate in self-powered mode, and what are the supply requirements?
Yes, the PCM2706CPJT supports self-powered operation using a 3.0–3.6 V supply applied to VCCP, VCCL, VCCR, and VDD pins, with PSEL (pin 16) held low. In this mode, VBUS (pin 24) is disconnected from USB power and tied to VDD. The internal analog blocks (DAC, PLL, headphone amps) draw from VCCP/VCCL/VCCR, while digital logic uses VDD. All supplies require local 1 μF ceramic decoupling. Self-powered operation enables use in battery-powered speakers or systems where USB bus power is unavailable or insufficient - maintaining full 98 dB SNR and <0.025% THD+N performance at 3.3 V nominal.
What is the role of the external ROM interface on the PCM2706CPJT?
The external ROM interface (CK on pin 14 and DT on pin 15) allows the PCM2706CPJT to load custom USB descriptors - including vendor ID (VID), product ID (PID), manufacturer string, and product string - from an external EEPROM during power-up. This enables branded device enumeration (e.g., "Acme USB Headphones") without modifying silicon or requiring host-side driver updates. The PCM2706CPJT initiates ROM read automatically; no firmware or host interaction is needed. This feature distinguishes PCM2706CPJT from PCM2707CPJT (which uses SPI instead) and supports mass customization in high-volume consumer audio manufacturing.
PCM2706CPJT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 32-TQFP
- Packaging:
- Tray
- Product Status:
- Active
- Function:
- Audio Signal Processor
- Applications:
- Audio Systems
- Number of Channels:
- 2
- Interface:
- I2C, SPI
- Voltage - Supply:
- 3V ~ 3.6V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Specifications:
- -
- Mounting Type:
- Surface Mount
- Grade:
- -
PCM2706CPJT FAQ
1.How can I place an order for PCM2706CPJT through Aetrix?
Please submit a Request for Quotation (RFQ) for PCM2706CPJT on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for PCM2706CPJT reliable?
The price and inventory of PCM2706CPJT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for PCM2706CPJT is usually 5 days.
3.What payment methods are accepted for PCM2706CPJT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for PCM2706CPJT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for PCM2706CPJT?
PCM2706CPJT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your PCM2706CPJT order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for PCM2706CPJT?
For technical support, including PCM2706CPJT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your PCM2706CPJT requirements.
6.How does Aetrix verify that PCM2706CPJT is sourced from the original manufacturer or authorized distributors?
All PCM2706CPJT products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that PCM2706CPJT meets industry standards.
7.What is the process for return or replacement of PCM2706CPJT?
All PCM2706CPJT units undergo pre-shipment inspection (PSI). If there is an issue with PCM2706CPJT, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The PCM2706CPJT part is unused and in its original packaging.
Return procedure for PCM2706CPJT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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