Synaptics® CX22721 I2S 2W CODEC
AudioSmart® Produ ct Brie f
Published November 7 2017. Copyright © 2017 Synaptics Incorporated. All rights reserved. PN: 190-000279-01 Rev. A
High Performance Stereo Class-D Amplifier for Advanced
In-Air Playback
The Synaptics CX 22721 is a high performance, stereo class-D amplifier
designed to enable adv anc ed in-air playback functionality for systems that us e
Synaptics Voice Processors.
The CX22721 features I2S audio I/O with I2C control, dedicated hardware DSP
effects for speaker tuning, and an Acoustic Echo Canceler (AEC) reference
output optimized for Synaptics Voice solutions.
The CX22721 provides 2W per channel output with 1% distortion at 5V PVDD
with a 4Ω speaker, and 1.3W per channel output with an 8Ω speaker. The Class-
D amplifier uses programmable signal dynamics management and power-
averaging technology to safely maximize sound pressure level.
The Synaptics SpeakerShield provides industry-leading, real-time prot ect ion with
features inc lud ing load-based DC detection, short-circuit, near-short, high
temperature, and over-temperature protection. The device also supports a high-
quality Line Out port with Headphone Drive capability.
The host interface provides selectable signaling levels of 1.8V and 3.3V. The
Digital-to-Analog converters (DACs) support sampling frequencies of 44.1k, 48k,
96k, and 192k Hz. Multiple General Purpose Input/Outputs (GPIOs) are available,
as well as a bi-directional External Amplifier Power-Down (EAPD) function for
advanced Power Management.
System Bloc k Diagram
CX22721
I
2
S Audio
with
I
2
C Control
EAPD/#SPKR_MUTE
#SPKR_MUTE/GPIO
GPIO
ADC
TX CH1/CH2
Boost LINE IN
DAC PORT A
LINE OUT
CLASS_D
AMP
Jack
Jack
Internal
PORT G
DAC
EQ/DRC
TX CH5/CH6
AEC Reference
Dedicated hardware DSP capabilities enable
a high-quality audio experience, especially
as part of a closed-loop system with a
Synaptics Voice Processor. This includes a
7-band/channel hardware EQ and a single-
band DRC (with a single knee) which,
independent of any hos t-based effects, can
be combined to optimize speaker response
and increase device loudness while
simultaneo usly min imizi ng distortion.
A programmable high-pass filter on the
Class-D outp ut remov es DC offset from the
I2S audio channels, protecting the speakers
from overheating.
Key Features
• Stereo AudioSmart Class-D Speaker
Amplifier
o Speaker Amp companion device for
Synaptics Voice Processors
o Digital I2S input and 44.1k, 48k, 96k,
and 192kHz sample r at e supp ort
o 2W output @ 1%THD
(PVDD=5V, 4Ω load)
o 1.3W output @ 1%THD
(PVDD=5V, 8Ω load)
o Programmable Dynamic Range
Compression (DRC) for SPL
maximization and speaker protection
o Programmab le 7-band Equalizer (EQ)
for speaker/chassis tuning and
distortion control
• 42-pin QFN package
Applications
• Voice-controlled STB
• Smart Bluetooth/WiFi speaker
• Voice interactive smart appliances
• Internet of Things (IoT) devices
Synaptics® CX22721 AudioSmart I2S 2W CODEC
High Performan ce Stereo Class-D Amplifier for Advanced In-Air P layback
Published November 7, 2017. Copyright © 2017 Synaptics Incorporated. All rights reserved. PN: 190-000279-01 Rev. A
Additional Features
• Stereo AudioSmart Class-D Speaker Amplifier
o Post processed I2S referenc e output for advanced echo cancellation with a Synaptics Voice Processor
o High quality, Stereo Line Out port with headphone drive capability
o GPIOs and bi-directional EAPD for advanced power management
o Host interfac e supports 1.8V or 3.3V signaling levels
• SpeakerShield real-time, load-based monitoring for DC, (near) short-circuit, and temperature protection
System Compatibility
• Stereo AudioSmart Class-D Speaker Amplifier
• I2S for Audio Streaming and I2C for control
• Windows 8.x/10
• Linux®
• Android™
Ordering Information
Ordering Part Number Part Number Revision
Audio Stereo Amplifier
Package Type
AudioSmart
Class-D
Conditions
CX22721-11Z
CX22721
-11Z
42-QFN, 5x5 mm
Yes
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 license of intellectual property from a third 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 tim e to
time and at its sole option, update the information contained in this document without notice.
INFORMATION CONTAINED IN THIS DOCUMENT IS PROVI DE D "AS-IS,” WITH NO EXPRESS OR IMPLIED WARRANTIES,
INCLUDING ANY IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 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
OF OR IN CONNECTION WITH THE USE OF THE INFORMA TION CONTAINED IN THIS DOCUMENT, HOWEVER CAUSED
AND BASED ON ANY THEORY OF LIAB ILITY, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
TORTIOUS ACTION, AND EVEN IF SYNAPTICS WAS ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. IF A TRIBUNAL
OF COMPETENT JURISDICTION DOES NOT PERMIT THE DISCLAIMER OF DIRECT DA MAGES OR ANY OTHE R DAMAGES,
SYNAPTICS’ TOTAL CUMULATIVE LIABILITY TO ANY PARTY SHALL NOT EXCEED ONE HUNDRED U.S. DOLLARS.
