Conexant Confidential • www.conexant.com • 037PBR00
USB/I2S Audio CODEC, AudioVoice DSP, Stereo
Class-D, Headphone Driver
Product 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/soundbars, portable multimedia/navigation
devices, Smart home intercom systems, media IP
phones, and Unified Communication peripherals.
The CX20709 offers multiple digital data and control
I/Os for flexible peripheral or MCU/MPU connectivity.
The device features one four-wire and one five-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 capabilities 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 102dB
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 ADCs supporting up to four
microphones or three stereo line-inputs. Different audio
sampling rates ranging from 8kHz to 96kHz are
generated directly from the master clock without the
need for an external PLL. The power-ef ficient integrated
class-D stereo amplifier operates at 5V or 3.3V with an
optional maximum power of 2.8W at a 4 load. For an
intercom application, the mono line-out supports 600
drivers that can drive the isolation transformer directly
without an external operational amplifier.
The on-chip DSP is designed to run a suite of VPAs and
audio post processing effects offered by Conexant. The
device features Conexant's soundbar algorithm for USB
5.1 channel soundbar 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 3.3V
for analog, and 1.8V for the digital core. An advanced
power management scheme can be configured to
achieve <7.55mW in sleep mode.
Applications
•PC speakers system
•LCD display/soundbar
•Home automation/intercom
•PND/PMP
•Multimedia IP phone
•Telepresence/Unified Communication device
•Embedded applications
Key Features
•
Four-wire and five-wire digital audio I/O (I2S/PCM/
SPDIF) that supports full-duplex independent sampling
rates and a master clock for an optional PCM/I2S slave
CODEC (S/PDIF-in available in CX20709-21Z)
•One two-wire I
2
C and one four-wire SPI slave
interface for an external MCU
•USB 2.0 compliant full-speed UAC interface
•Single-ended or differential line output
System Block Diagram
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
CX2070x USB/I2S Audio CODEC
ImagingSmart™ Product Brief
DRAFT
037PBR00
© 2014 Conexant Systems, Inc. All rights reserved.
www.conexant.com
Headquarters: 1901 Main Street, Suite 300 Irvine, CA,92614
General Information: U.S. and Canada: 888-855-4562 | International: 1 + 949-483-3000
CX2070x USB/I2S Audio CODEC | ImagingSmart™ Product Brief
Additional Features
•Supports dual USB playback
endpoints (available in CX20709-
21Z)
•Stereo digital microphone, up to
a 12MHz clock rate (available in
CX20709-21Z)
•Eight GPIO pins
•2.8W x 2 BTL filterless stereo
class-D speaker amplifier—Low
EMI class-D amplifier output with
spread spectrum and common
mode scrambler
•Integrated 50mW headphone
driver with jack sense
•Separate mixed mono line-output
for sub-woofer or intercom usage
•Three single-ended stereo or one
differential stereo analog audio
inputs
•Up to four microphone interfaces
with on-chip bias supply
(available in CX20709-21Z)
•24-bit DAC/ADC, SNR 102dB,
THD–92dB at 48kHz 3.3V—In
DSP mode, the processing limits
the input and output to a 16-bit
effective resolution
•Audio sample rates of 8kHz,
16kHz, 22.05kHz, 24kHz, 32kHz,
44.1kHz, 48kHz, 88.2kHz, and
96kHz
•90dB dynamic range with 0.1%
THD+n at a 4 load
•12-bit ADC multiplexed to
support analog volume
potentiometer and DC level
detection
•Flexible power management
•Variable master clock rates
•Configurable on-chip proprietary
voice/audio processing
–Sub-band AEC
–Dual microphone beam
forming
–Noise reduction
–Dynamic loudness adaptor
–Microphone AGC
–Sub-band line echo
cancellation (two-way
intercom applications)
–Digital equalizer (10 bands/
channel)
–Dynamic range compression
–Fourth order digital crossover
for subwoofer line-out
–Conexant soundbar
algorithm for USB 5.1
channel soundbar
enhancement (available in
CX20709-21Z)
•SPoC configuration toolbox
–Fast configuration through
USB-to-I2C from a PC
–Data path, I/O setup, and
DSP parameter adjustment
–Output log for convenient
MCU programming
Ordering Information
Note: All devices are lead-free (Pb-free) and RoHS compliant.
Ordering Part Number Part Number Description Package
DSAC-L709-21CH CX20709-21Z USB/I2S Audio CODEC 76QFN
DSAC-L709-12CH CX20709-12Z Conexant does not recommended this part number for new designs. 76QFN
CX20709-EVK2 CX20709 EVK2 CX20709-21Z EVK -
CX20709-EVK2-IN CX20709 EVK2 IN CX20709-21Z Intercom Daughterboard -
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