Sound Terminal 2.1-channel high-efficiency digital audio system

The STA350Bx 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, and all-digital amplification.

The STA350Bx is based on an FFX (fully flexible amplification) processor, a proprietary technology from STMicroelectronics. FFX is the evolution and the enlargement of ST’s ternary technology: the new processor can be configured to work in ternary, binary, binary differential and phase-shift PWM modulation schemes.

The STA350Bx contains the ternary, binary and binary differential implementations, a subset of the full capability of the FFX processor.

The STA350Bx 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 STA350Bx 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 18 W + 1 x 40 W of music output power, by using standard 4 and 8 W speakers. Two channels can be provided by two full-bridges, providing up to 2 x 50 W of music power, by using standard 6 W speaker or 2 x 40 W by using 8 W speakers at 25 V. The IC can also be configured as 2.1 channels with 2 x 40 W provided by the device and external power for FFX power drive. If configured as mono-BTL, the latter is capable of providing up to 1 x 90 W on a standard 3 W load or 1 x 75 W by using a 4 W, setting the supply voltage at 25 V. Please refer to the package thermal characteristics and application suggestions for more details.

Also provided in the STA350Bx are a full assortment of digital processing features. This includes up to 8 programmable biquads (EQ) per channel. Special digital signal processing techniques are available in order to manage low-frequency quantization noise in case of very low frequency cutoff filter thresholds. The coefficient range -4..4 allows the easy implementation of high shelf filters. Available presets allow the advantage of earlier time-to-market 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 output power level. This feature independently processes the two bands, controlling dynamically the output power level in each band and so providing better sound clarity.

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.

Key Features

  • Wide-range supply voltage
    • 5 V to 26 V (operating range)
    • 30 V (absolute maximum rating)
  • Four power output configurations
    • 2 channels of ternary PWM (stereo mode) (2 x 50 W into 6 W at 25 V)
    • 3 channels - left, right using binary and LFE using ternary PWM (2.1 mode) (2 x 18 W + 1 x 40 W into 2 x 4 W, 1 x 8 W at 25 V)
    • 2 channels of ternary PWM (2 x 50 W) + stereo lineout ternary
    • 1 channel of ternary PWM as mono-BTL (1 x 90 W into 3 W at 24.5 V)
  • FFX™ 100 dB SNR and dynamic range
  • Selectable 32 to 192 kHz input sample rates
  • I2 C control with selectable device address
  • Digital gain/attenuation +42 dB to -80 dB with 0.125 dB/step resolution
  • Soft-volume update with programmable ratio Individual channel and master gain/attenuation
  • Two independent DRCs configurable as a dual-band anti-clipper (B2DRC) or independent limiters/compressors
  • EQ-DRC for DRC based on filtered signals
  • Dedicated LFE processing for bass boosting with 0.125 dB/step resolution
  • Audio presets:
    • 15 preset crossover filters
    • 5 preset anti-clipping modes
    • Preset nighttime listening mode Individual channel and master soft/hard mute
  • Independent channel volume and DSP bypass
  • Automatic zero-detect mute
  • Automatic invalid input-detect mute
  • I2 S input data interface
  • Input and output channel mapping
  • Up to 8 user-programmable biquads per channel 3 coefficient banks for EQ presets storing with fast recall via I2 C interface
  • Extended coefficient dynamic up to -4..4 for easy implementation of high shelf filters
  • 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
  • Selectable clock input ratio
  • 96 kHz internal processing sample rate with quantization error noise shaping for very low cutoff frequency filters
  • Thermal overload and short-circuit protection embedded
  • Video apps: 576 x Fs input mode supported
  • Fully compatible with STA339BW and STA339BWS


Technical Documentation

Product Specifications
Description Version Size
DS7146 DS7146: 2.1-channel high-efficiency digital audio system Sound Terminal® 5.0 1 MB
Application Notes
Description Version Size
AN4118 AN4118: APWLink USB interface board for Sound Terminal® demonstration boards 2.0 1 MB
AN3984 AN3984: IIR filter design equations for Sound Terminal® devices 1.1 493 KB
AN3340 AN3340: Loudspeaker characterization and compensation 1.3 3 MB
AN3383 AN3383: STA350BW 2.0-channel demonstration board 1.1 5 MB
AN4569 AN4569: Using Sound Terminal® STA3xyBWz devices in 2.1 channel applications 1.0 2 MB
User Manuals
Description Version Size
UM1545 UM1545: Using the Audio Processor Workbench (APWorkbench) 1.0 3 MB

Publications and Collaterals

Description Version Size
APWorkbench software for audio ICs and MEMS microphones 1.0 2 MB
Description Version Size
Analog audio solution 1.0 1 MB
FFX - Full flexible amplification 4 MB
FFX Full flexible amplification 1.0 4 MB

Tools and Software

STM32 Open Development Environment
Evaluation Tools
Product Evaluation Tools
Support & Community

Sample & Buy

Part Number Marketing Status Quantity Unit Price (US$) * Package Packing Type Operating Temperature (°C) (min) Operating Temperature (°C) (max) ECCN (EU) ECCN (US) Country of Origin More info Order from ST Order from Distributors
STA350BWTR Active 1000 2.556 PowerSSO 36 Tape And Reel -20 85 NEC EAR99 MALAYSIA MORE INFO No availability reported, please contact our Sales office

(*) 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

Quality & Reliability

Part Number Marketing Status Package Grade RoHS Compliance Grade Material Declaration**
STA350BWTR ActivePowerSSO 36IndustrialEcopack2 0 0

(**) 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.