Synaptics® CX20 924 4-mic Far-Field Voice Input Processor SoC
AudioSmart® Produ ct Brie f
Published November 7, 2017. Copyright © 2017 Synaptics Incorporated. All rights reserved. PN: 190-000281-01 Rev. A
Four-Microphone Far-Field Input Subsys te m with Integrated
Low-Pow er Wake Word
The Synaptics CX 20924 is a high-performance, 4-mic far-field voice input
processor System-on-Chip (SoC). The CX20924 is the first product in this
category with an integrated voice trigger function that supports a low system
power Wake-on-Voice ( WoV) function and 360-degree Smart Source Locator
(SSL) that detects user's locati on around the dev ice .
The device includes a Pulse Density Modulated (PDM) interface with digital
decimation filt er s that su pports up to four high-performance digital microphones,
a powerful dual core 32-bit hardware Digital Signal Processor (DSP), and
integrated power management.
Combined with Synaptics’ AudioSmart® far-field voice input processing software
suite, including four-microphone Smart Source Pickup (SSP) noise suppression
and full-duplex Acoustic Echo Cancellation (AEC), the CX20924 is the ideal
turnkey solution for adding voice control, 360-degree SSL, voice search, and
Voice over Internet Protocol (VoIP)/speakerphone functionalities to SmartTV,
Smart Speakers, Set-Top Box (STB), Smart appliances, and many tabletop
consumer electr onics devices.
The CX20924 device supports four digital microphones using two stereo digital
PDM microphone external interfaces. Each Digital Microphone Interface (DMIC)
supports sample rates from 8kHz to 96kHz. The CX20924 assists manufacturers
and developers to prototype and develop Am azon Alexa™-enabled devices.
Synaptics’ proprietary far-field AudioSmart algorithms levera ge the built-in
hardware to deliver a superior voice interactive experience in the most
challenging room environments. The voice processing chain also supports
multiple modes of processing, which are independently optimized for voice
communication and automatic speech rec ognition.
System Block Diagram
PCM DC/DC PLL DMAs Timers Debug
I2S Out
Full Speed
USB
Echo Ref.
I2S/SPDIF
I2C Slave SPI FLASH I/F UART GPIO WoV
Interrupt
Far Field
Voice
Algorithms
Voice Trigger
Engine
DSP CORE
Bridge
Memory
4 x DMIC
MCLK Out
When the PDM microphone and DSP are
active in the WoV mode, the device
consumes les s than 70mW, which is well
below the 0.5W EC 1275/2008 requirement
for standby power.
Key Features
• 4-mic SSL identified the user’s direction
in 360 degrees.
• Low-power W oV mode with embedded
third-party voice wake-up engi ne
• Enables premium-performance
Automatic Speech Recognition (ASR)
and excellent voice clarity with four
microphones using Synaptics’
AudioSmart voice input processing
software, w hich inc lud es:
o 4-mic SSP noise suppression
o Full-duplex AEC
• Compatible with multiple leading
embedded and server-based s peec h
recognition vendors
Applications
• Voice-controlled Sm art TV/STB
• Smart Bluetooth/WiFi speaker
• Voice interactive smart appliances
• Internet of Things (IoT) devices
Synaptics® CX20924 4-mic Far-Field V oice Input Processor SoC
AudioSmart Produc t Brief
Published November 7, 2017. Copyright © 2017 Synaptics Incorporated. All rights reserved. PN: 190-000281-01 Rev. A
Additional Features
• Powerful, dual-core 32 -bit DSP
• I2S serial data interfaces
• I2C serial cont rol interface
• USB 2.0 full-speed compliant audio data and control interface
• Serial Peripheral Interface (SPI) for low-cost flash support
• Supports four MEMS digital microphones using two stereo data pins
• Only supports digital microphones
• 7x7mm 60 QFN package
Ordering Information
Ordering Part Number
Part Number
Description
Package
Conditions
CX20924-21Z
CX20924
Four-Microphone Far-Field Voice
Processor SoC
60 QFN 7x7m m
0 to 70°C
The devices in this publication are lead-free (Pb-Free) and China RoHS compliant.
Contact your local Synaptics sales office for advanced software options.
Trademarks
Synaptics, the Synaptics logo, and AudioSmart, are trademarks or registered trademarks of Synaptics Inc orporated or its
affiliates in the United States and/or other c ountries.
Notice
Use of the materials may require a li c ense of intellec tual property from a thi rd party or from Synaptics. This document conveys no
express or im plied licenses to any intellectual property rights belonging to Synaptics or any other party. Synaptics may, from time to
time and at its sole option, update the information contained in this document without notice.
INFORMATION CONTAINED IN THIS DOCUMENT IS PRO V IDED "AS-IS,” WITH NO EXPRESS OR IMPLIED WARRANTIES,
INCLUDING ANY IMPLIED WA RRA NTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICUL A R PURPOSE, AND ANY
WARRANTIES OF NON-INFRINGEMENT OF ANY INTELLECTUAL PROPERTY RIGHTS. IN NO EVENT SHALL SYNAPTICS
BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, PUNITIVE, OR CONSEQUENTIAL DAMAGES ARISING OUT
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AND BASED ON ANY THEORY OF LIAB ILITY, WHETHER IN AN ACTION OF CONTRA CT, NEGLIGENCE OR OTHER
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