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2.1-channel high-efficiency digital audio system
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The STA339BW is an integrated solution of digital audio processing, digital amplifier control, and FFX-power output stage, thereby creating a high-power single-chip FFX®solution comprising high-quality, high-efficiency, all digital amplification.

STA339BW is based on FFX (fully flexible amplification) processor, an STMicroelectronics proprietary technology. FFX is the evolution and the enlargement of the ST ternary technology: the new processor can be configured to work in ternary, binary, binary differential and phase shift PWM modulation schemes.

STA339BW contains the ternary, binary and binary differential implementations, a subset of the full capability of the FFX processor.

The STA339BW is part of the Sound Terminal®family that provides full digital audio streaming to the speaker, offering cost effectiveness, low power dissipation and sound enrichment.

The STA339BW power section consists of four independent half bridges. These can be configured via digital control to operate in different modes. 2.1 channels can be provided by two half bridges and a single full bridge, providing up to 2 x 9 W + 1 x 20 W of power output. Two channels can be provided by two full bridges, providing up to 2 x 20 W of power. The IC can also be configured as 2.1 channels with 2 x 20 W provided by the device and external power for FFX power drive.

Also provided in the STA339BW are a full assortment of digital processing features. This includes up to 8 programmable 28-bit biquads (EQ) per channel and bass/treble tone control. Available presets enable a time-to-market advantage by substantially reducing the amount of software development needed for certain functions. This includes audio preset volume loudness, preset volume curves and preset EQ settings. There are also new advanced AM radio interference reduction modes. Dual-band DRC dynamically equalizes the system to provide speaker linear frequency response regardless of the output power level. This feature independently processes the two bands, controlling dynamically the output power level in each band and so providing better sound quality.

The serial audio data input interface accepts all possible formats, including the popular I2S format. Three channels of FFX processing are provided. This high-quality conversion from PCM audio to FFX PWM switching waveform provides over 100 dB SNR and dynamic range.

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Errata Sheet
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Key Features

  • Wide voltage supply range
  • 5 V to 26 V (operating range)
  • 30 V (absolute maximum rating)
  • 3 power output configurations
  • 2 channels of ternary PWM (stereo mode) (2 x 20 W into 8 Ω at 18 V)
  • 3 channels - left, right using binary and LFE using ternary PWM (2.1 mode) (2 x 9 W + 1 x 20 W into 2 x 4 Ω, 1 x 8 Ω at 18 V)
  • 2 channels of ternary PWM (2 x 20 W) + stereo lineout ternary
  • 2.1 channels of 24-bit FFX®100 dB SNR and dynamic range
  • Selectable 32 to 192 kHz input sample rates
  • I2C control with selectable device address
  • Digital gain/attenuation +48 dB to -80 dB with 0.5 dB/step resolution
  • Soft volume update with programmable ratio
  • Individual channel and master gain/attenuation
  • Two independent DRC configurable as a dual-band anti-clipper (B2DRC) or as independent limiters/compressors
  • EQ-DRC for DRC based on filtered signals
  • Dedicated LFE processing for bass boosting with 0.5 dB/step resolution
  • Audio presets:
  • 15 preset crossover filters
  • 5 preset anti-clipping modes
  • Preset night-time listening mode
  • Individual channel and master soft/hard mute
  • Independent channel volume and DSP bypass
  • Automatic zero-detect mute
  • Automatic invalid input-detect mute
  • 2-channel I2S input data interface
  • Input and output channel mapping
  • Up to 8 user-programmable biquads per channel with 28-bit resolution
  • 3 coefficient banks for EQ presets storing with fast recall via I2C interface
  • Bass/treble tones and de-emphasis control
  • Selectable high-pass filter for DC blocking
  • Advanced AM interference frequency switching and noise suppression modes
  • Selectable high- or low-bandwidth noise-shaping topologies
  • Variable max power correction for lower full-power THD
  • Selectable clock input ratio
  • 96 kHz internal processing sample rate, 24 to 28-bit precision
  • Thermal overload and short-circuit protection embedded
  • Video apps: 576 * fSinput mode supported
  • Fully compatible with STA339BWS.

Circuit Diagram

Design Resources


Technical Documentation

Product Specifications

Description Version Size
DS6004: 2.1 channel high-efficiency digital audio system
7.0 1,386 KB

Application Notes

Description Version Size
AN3340: Loudspeaker characterization and compensation
1.3 3,944 KB
AN3984: IIR filter design equations for Sound Terminal® devices
1.1 494 KB
AN4118: APWLink USB interface board for Sound Terminal® demonstration boards
2.0 1,029 KB
AN4569: Using Sound Terminal® STA3xyBWz devices in 2.1 channel applications
1.0 2,336 KB

User Manual

Description Version Size
UM1545: Using the Audio Processor Workbench (APWorkbench)
1.0 3,221 KB

Presentations & Training Material

Training Material

Description Version Size
Learn the basics about STSpeakerSafe technology
1.0 197 KB

Publications and Collaterals


Description Version Size
APWorkbench software for audio ICs and MEMS microphones
2,349 KB


Description Version Size
Analog audio solution
1.0 1,371 KB
FFX - Full flexible amplification
4,722 KB

Sample & Buy

Part Number Marketing StatusPackagePacking TypeOperating Temperature (min) Operating Temperature (max) Automotive GradeOrder From STUnit Price (US$)*
@ 1000
Distributor AvailabilityRoHS Compliance GradeDownload
Material Declaration**
STA339BWTRActivePowerSSO 36Tape And Reel070_-2.521Distributor reported inventory date: 2016-02-08
Distributor NameRegionStockMin. order
Farnell Element14Order NowEUROPE621

(*) Suggested Resale Price per unit (USD) for BUDGETARY USE ONLY. For quotes, prices in local currency, please contact your local ST Sales Office or our Distributors
(**) The Material Declaration forms available on may be generic documents based on the most commonly used package within a package family. For this reason, they may not be 100% accurate for a specific device. Please contact our sales support for information on specific devices.
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