Scalable digital microphone processor

The STA321MP is a PDM, high-performance, multichannel processor with ultra-low quiescent current. It is designed for general-purpose digital microphone applications. The device is fully digital and is comprised of three main sections. The first section is the PDM input interface which can accept up to six serial digital inputs. The second section is a high-quality audio processor allowing flexible channel mixing/muxing and provides up to 10 biquads for general sound equalization and voice enhancement with independent volume control. The last block is the I²S output interface which streams out the processed digital audio. The output interface can also be programmed for flexible channel mapping. The device offers some of the most commonly required audio enhancements such as programmable voice tuning and equalization, limiter/compressor for improved voice quality, multiband selection for customizable microphone usage, and configurable wind-noise rejection. The embedded digital processor allows the microphone processing to be offloaded from the main CPU or SoC to the device.

Key Features

  • 8 digital processing channels each 24-bits
    • 6 channels of PDM input
    • 2 additional virtual channels
  • >100 dB SNR and dynamic range
  • Digital gain/attenuation 58 dB to -100 dB in 0.5 dB steps
  • Soft volume update
  • Individual channel and master level control
  • Up to 10 independent 32-bit user-programmable biquads (EQ) per channel
  • Bass/treble tone control
  • Pre- and post-EQ full 8-channel input mix on all 8 channels
  • Dual independent limiters/compressors
  • Dynamic range compression or anti-clipping modes
  • Individual channel and master soft/hard mute
  • 3 I²S data outputs
  • I²S data output channel mapping function
  • Independent channel volume and DSP bypass
  • Channel mapping of any input to any processing channel


Technical Documentation

Product Specifications
Description Version Size
DS8825 DS8825: Scalable digital microphone processor 6.0 1 MB
Application Notes
Description Version Size
AN3984 AN3984: IIR filter design equations for Sound Terminal® devices 1.1 493 KB
AN3340 AN3340: Loudspeaker characterization and compensation 1.3 3 MB
AN4146 AN4146: STSmartVoice demonstration board STEVAL-MKI126Vx 2.0 3 MB

Publications and Collaterals

Description Version Size
ST’s solutions for mobile devices 3.2 3 MB

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Sample & Buy

Part Number Package Packing Type Operating Temperature (°C) (min) Operating Temperature (°C) (max) Marketing Status Unit Price (US$) * Quantity ECCN (EU) ECCN (US) Country of Origin More info Order from ST Order from Distributors
STA321MPL LQFP 64 10x10x1.4 Tray -40 90 NRND - - NEC EAR99 - MORE INFO No availability reported, please contact our Sales office
STA321MPLTR LQFP 64 10x10x1.4 Tape And Reel -40 90 Active 3.551 1000 NEC EAR99 MALAYSIA MORE INFO No availability reported, please contact our Sales office
STA321MPTR VFQFPN 59 8x8x0.9 Tape And Reel -40 90 Preview - - NEC EAR99 - 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**
STA321MPL NRNDLQFP 64 10x10x1.4IndustrialEcopack1
STA321MPLTR ActiveLQFP 64 10x10x1.4IndustrialEcopack1
STA321MPTR PreviewVFQFPN 59 8x8x0.9IndustrialEcopack3

(**) 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.