CX20709
USB/I2S Audio CODEC, Audio/Voice DSP, Stereo Class-D, Headphone
Driver
Overview
The CX20709 is one of Conexant's Audio/
Voice DSP CODEC family solutions with
highly integrated hardware DSP, CODEC,
Class-D amplifier, USB, I2S, S/PDIF, and
I2C interfaces. The solution features a suite
of turnkey audio and voice enhancement
algorithms designed for convergence audio
entertainment and voice communication
applications, such as PC Docking System/
Sound-Bar, Portable Multimedia/Navigation
Devices, Smart Home Intercom System,
Media IP Phone, and Unified
Communication Peripherals.
The CX20709 offers multiple digital data
and control I/O for flexible peripheral or
MCU/ MPU connectivity. The device
features one 4-wire and one 5-wire digital
audio interface, which can be mixed or
multiplexed to support bi-directional I2S,
PCM, and S/PDIF. The device can be
controlled and configured by both read and
write capability through I2C and SPI. The
device features a USB 2.0 Compliant Audio
Class interface (full-speed for data and
control) and a UART interface for the
external MCU/MPU interface.
The device integrates three high-
performance 102 dB SNR, 24-bit DACs for
2.1CH speaker output, capless headphone
output, and single-ended/differential line-
output. The analog input paths feature four
high performance, 24-bit ADC supporting up
to four microphones or three stereo Line-
Inputs. Different audio sampling rates
ranging from 8 kHz to 96 kHz are generated
directly from the master clock without the
need for external PLL. The power-efficient
integrated Class-D stereo amplifier operates
at 5 V or 3.3 V with an optional maximum
power of 2.8 W at a 4 Ω load. For intercom
application, the mono line-out supports
600 Ω drivers, which can drive the isolation
transformer directly without an external
operational amplifier.
The on-chip DSP is designed to run a suite
of Voice Processing Algorithms and Audio
Post Processing Effects offered by
Conexant. The device features Conexant's
soundbar algorithm for USB 5.1 channel
sound-bar enhancement. The audio
designer has the ability to adjust and
optimize performance on the target system
by using the SPoC Configuration Toolbox.
The CX20709 operates at supply voltages
down to 3.3 V for analog and 1.8 V for the
digital core. An advanced power
management scheme can be configured to
achieve <7.55 mW in sleep mode.
Applications
PC Speakers System
LCD Display/SoundBar
Home Automation/Intercom
PND/PMP
Multi Media IP Phone
Telepres e n ce / Un ifi e d Co m m u ni c at io n
Device
Embedded Applications
Part Number CX20709
Description USB/I2S Audio CODEC, Au-
dio/Voice DSP, Stereo Class-D, Headphone
Driver
Ordering
Number Part Number Package Description
DSAC-L709-21CH CX20709-21Z 76QFN
DSAC-L709-12CH CX20709-12Z 76QFN Not recommen ded for new design
CX20709-EVK2 CX20709-EVK2 CX20709-21Z Evaluation Kit
CX20709-EVK2-IN CX20709-EVK2-IN CX20709-21Z Intercom Daughter Board
All devices are lead-free (Pb Free) and RoHS compliant
CODEC Features
Functional Block Diagram
Conexant Product Portfolio
Conexant’s comprehensive product portfolio includes solutions for imaging, audio, video surveillance, and embedded modem applications.
Conexant products are not intended for use in medical, lifesaving or life sustaining appli-
cations. Conexant customers using or selling Conexant products for use in such applica-
tions do so at their own risk and agree to fully indemnify Conexant for any damages
resulting from such improper use or sale.
The following are trademarks of Conexant Systems, Inc.: Conexant® and the Conexant C
symbol, SmartAudio, SmartJack, SmartCD, and SmartDAA®. Product names or services
listed in this publication are for identification purposes only, and may be trademarks of
third parties. Third-party brands and names are the property of their respective owners.
For additional disclaimer information, please consult Conexant's Legal Information post-
ed at www.conexant.com, which is incorporated by reference.
Reader Response: Conexant strives to produce quality documentation and welcomes your
feedback. Please send comments and suggestions to tech.pubs@conexant.com. For
technical questions, contact your local Conexant sales office or field applications engi-
neer.
www.conexant.com
General Information:
U.S. and Canada:
(888) 855-4562
International:
1+ (949) 483-3000
Headquarters
4000 MacArthur Blvd.
Newport Beach, CA 92660
Doc# PBR-202964
© 2012 Conexant Systems, Inc. All Rights
Reserved. Conexant and the Conexant logo
are registered trademarks of Conexant
Systems, Inc. All other trademarks are owned
by their respective owners. Although
Conexant strives for accuracy in all its
publications, this material may contain errors
or omissions and is subject to change without
notice. THIS MATERIAL IS PROVIDED AS IS
AND WITHOUT ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING MERCHANT
ABILITY, FITNESS FOR A PARTICULAR
PURPOSE AND NON-INFRINGEMENT.
Conexant shall not be liable for any special,
indirect, incidental or consequential damages
as a result of its use.
DMA
DSP X2
Memory DMA
DAC
DAC
DAC
ADC
ADC
PCM/I2S PCM/I2S
Controller
SPI
I2C Slave UART
Jack
Sense
Clock
Circuitry
Bias
Generator
MON
ADC
I2S_PCM_1_CLK
I2S_PCM_1_RX_WS
I2S_PCM_1_RX_DAT
I2S_PCM_1_TX_WS/SPDIF_OUT
USB
I2S_PCM_1_TX_DAT
I2S_PCM_2_WS
I2S_PCM_2_CLK/DMIC_CLK
I2S_PCM_2_RX_DAT/DMIC_IN/SPDIF_IN
I2S_PCM_2_TX_DAT
USB_DP
USB_DM
USB_5VDET
I2C_SPI_SCL
UART_RX
UART_TX
NVCLK
NVDAT
I2C_SPI_CSN
SPI_MISO
I2C_SDA/SPI_MOSI
GPO 0
GPO 1
KS0
KS1
KS2
Volume
LINE_OUT_LP
LINE_OUT_LN
(SE or Diff, LINE_OUT_LN
10 kΩ line)
CLASSD_LP
CLASSD_LN
(2.5W Class-D 4 Ω Out)
HP_OUT_R
(Capless HP Out 32 Ω)
MONO_OUT_N
(SE or Diff, 600 Ω or 10 kΩ line)
HP_OUT_L
(Capless HP Out 32 Ω)
MIC_IN_L
MIC_IN_R
MICBIAS_L
MICBIAS_R
XTLI
XTLO
SENSE_A
Σ
ADC
LINE_IN_1L_LP (SE or Diff Line In)
MIC_IN2_L/LINE_IN_3L
M
M
M
Σ
ADC
LINE_IN_1R_RP (SE or Diff Line In)
MIC_IN2_R/LINE_IN_3R
M
M
M
GPO2
GPO3
GPO4
(SE or Diff Line In)
LINE_IN_2L_LN
(SE or Diff Line In)
LINE_IN_2R_RN
PASS_THRU
PASS_THRU
VOLT_MON
MONO_OUT_P
(SE or Diff, 600 Ω or 10 kΩ line)
CLASSD_RP
CLASSD_RN
(2.5W Class-D 4 Ω Out)
LINE_OUT_RP
LINE_OUT_RN
(SE or Diff, LINE_OUT_LN
10 kΩ line)
I2C_EN/MCLK
DMIC_IN
DMIC_CLK
DMA
L
R
MCLK
4-wire and 5-wire digit al a udio I/ O (I 2S/
PCM/SPDIF), supporting full dup lex
independent sampling rates, master
clock for optional PCM/I2S slave codec
(SPDIF-in available in CX20709-21Z)
One 2-wire I2C and one 4-wire SPI
slave interfa c e for external MCU
USB 2.0 Compliant full speed UAC
Interface
Supporting dual USB playback end
points (available in CX20709-21Z)
Stereo Digital Microphone, up to
12 MHz clock rate (available in
CX20709-21Z)
Eight GPIO pi ns
2.8 W x 2 BTL filter-less stereo Class-
D Speaker Amplifier
– Low EMI Class-D amplifier output
with Spread Spectrum and
common mode scrambler
Integrated 50 mW headphone driver
with jack sense
Single-ended or differential line output
Separate mixed mono line-output for
sub-woofer or intercom usage
Three single-ended stereo or one
differential stereo analog audio input
Up to 4 microphone interfaces with on-
chip bias supply (availa ble in
CX20709-21Z)
24-bit DAC/ADC, SNR 102 dB, THD -
92 dB at 48 kHz 3.3 V
– In DSP mode, the processing will
be limited the input and output to
16-bit effective resolution
Audio sample rat e: 8,16, 22.05, 24, 3 2,
44.1, 48, 88.2, 96 kHz
90 dB Dynamic Range with 0.1%
THD+N at 4 Ω load
12-bit ADC multiplexed to support
analog volume potentiometer and DC
level det ec tion
Flexible Power Management
Variable master clock rates
Configurable On-Chip proprietary
Voice/Audio Processing
– Subband Acoustic Echo
Cancellation
– Dual Microphone Beam Forming
– Noise Reduction
– Dynamic Loudness Adaptor
– Microphone Automatic Gain
Control
– Subband Line Echo Cancellation
(2-way intercom applications)
– Digital Equalizer (10 bands/
channel)
– Dynamic Range Compression
– 4th Order Digital Crossover for
Subwoofer Line-out
– Conexant sound-bar algorithm for
USB 5.1 channel sound-bar
enhancement (available in
CX20709-21Z)
SPoC Configuration Toolbox
– Fast configuration via USB-to-I2C
from PC
– Data path, I/O setup, and DSP
parameter adjustmen t
– Output log for convenient MCU
programming
