DS4201
USB Audio DAC
www.dalsemi.com
FEATURES
§
Fully USB Core Class v1.0 Compliant
§
Fully USB Audio Device Class v1.0
Compliant
§
Complete Stereo DAC System
§
16–bit
Σ∆
DAC
§
Analog Post Filter
§
44.1 KHz, 48 KHz Sampling Rates
§
>80 dB S/N DAC Performance
§
Audio System Power Management
§
8 and 16–Bit PCM Digital Data Formats
§
Integrated USB Compliant Transceiver
§
High Rate 12 Mbps USB Interface
§
Analog Output Mixing for Auxiliary Inputs
§
Multiple Power Configurations Including
Completely USB Powered
§
3.3V – 5.0V Operating Range
PIN ASSIGNMENT
VD
NC
NC
DGND
SPM
X2I
X2O
DGND
X1I
X1O
VB
D-
D+
DGND
1
2
3
4
5
6
7
8
9
10
11
12
13
14
28
27
26
25
24
23
22
21
20
19
18
17
16
15
NC
NC
NC
SUSO
VCM
VREFI
VA
AGND
LOUT
ROUT
LMIC
RMIC
LAUX
RAUX
28-PIN DIP 600 MIL
NC
DGND
NC
NC
VD
NC
NC
NC
NC
SUSO
NC
44
1
ALE
WR
RLINK
RLCLK
DVSS
RCLK
RCHCLK
RSER
RSYNC
RLOS/LOTC
SYSCLK
11
12
VB
D-
NC
D+
DGND
NC
NC
RAUX
LAUX
RMIC
LMIC
44-PIN QFP (10mm x 10mm)
34
33
NC
NC
VCM
NC
VREGI
VA
NC
AGND
LOUT
NC
ROUT
23
22
ORDERING INFORMATION
Part Number
DS4201
DS4201F
Description
28-pin DIP
44-pin QFP
DESCRIPTION
The DS4201 Universal Serial Bus (USB) audio device is a complete interface solution for USB based PC
digital audio playback. Integrating a USB device core, stereo 16–bit sigma–delta DAC and fixed function
DSP processing, as shown in Figure 1, the DS4201 is designed specifically for USB digital speaker
implementations. Digital–to–analog audio data processing supports 8 and 16–bit PCM stereo/mono
formats at 44.1 KHz and 48.0 KHz sampling rates. Additionally, analog output mixing of line and
microphone inputs provide legacy and hybrid speaker capabilities.
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DS4201
The DS4201 USB function core fully complies with both the USB Specification v1.0 and the USB
Device Class Definition for Audio Devices v1.0. To complete the USB capability of the DS4201, a USB
compliant transceiver is integrated to eliminate the need for any additional support chips. Organization of
the DS4201 in an USB context is shown in Figure 2. For the USB enabled PC, the DS4201 is an ideal
digital output solution for high quality audio and control within the speaker or monitor enclosure. Its USB
control and capabilities as well as its high quality audio characteristics also comply with next generation
PC system and audio standards put forth by industry leaders.
RELATED DOCUMENTS
This data sheet references or complies with the following USB specifications which are considered to be
part of the DS4201 device specification. These documents may be obtained from the USB Implementers
Forum web site:
www.usb.org.
Universal Serial Bus Specification
Universal Serial Bus Device Class Definition for Audio Devices
FUNCTIONAL BLOCK DIAGRAM Figure 1
SIGNAL SUMMARY
SIGNAL NAME
D+
D-
SPM
SUSO
TYPE
I/O
I/O
I
O
FUNCTION
USB data – non-inverted signal of differential data pair.
USB data – inverted signal of differential data pair.
Suspend Power Mode – controls device power configuration when a
USB suspend state is entered.
Suspend Output – buffered USB suspend state output from USB
device core. When HIGH the USB is in an active non-suspended
state, when LOW the USB has entered a suspended state. This is an
open drain output and requires a pull-up.
Microphone right channel analog input to the analog output mixer.
Microphone left channel analog input to the analog output mixer.
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RMIC
LMIC
I
I
DS4201
SIGNAL NAME
RAUX
LAUX
ROUT
LOUT
VCM
VREFI
TYPE
I
I
O
O
O
I
FUNCTION
Auxiliary right channel analog input to the analog output mixer.
Auxiliary left channel analog input to the analog output mixer.
Right channel analog audio output from the mixer, 0.5 V
RMS
or 1.0
V
RMS
centered about V
REF.
Left channel analog audio output from the mixer, 0.5 V
RMS
or 1.0
V
RMS
centered about V
REF.
DC bias point to which all AC coupled inputs are centered.
Nominally V
REF
= 0.4 x VA.
Filter capacitor connection for internal voltage reference node.
Connect a 10µF and 0.1µF capacitor to V
REFI
, very close to the pin,
for best operation.
Power supply input for analog functions. Range: 3.0 – 5.5V.
Power supply input for digital functions. Range: 3.0 – 5.5V.
USB I/F power supply input. Range: 3.0 – 3.6V.
Digital ground.
Analog ground.
Crystal 1 input. Use a 12.0 MHz, fundamental mode, parallel
resonant crystal. A 12.0 MHz CMOS clock source may also be used.
Crystal 1 output. Connect to other side of crystal 1 if used.
Crystal 2 input. Use a 12.888 MHz, fundamental mode, parallel
resonant crystal. A 12.288 MHz CMOS clock source may also be
used.
Crystal 2 output. Connect to other side of crystal 2 if used.
No connect. Leave these pins unconnected.
VA
VD
VB
DGND
AGND
X1I
X10
X2I
I
I
I
I
I
I
O
I
X2O
NC
O
DS4201 OPERATION
Operation of the DS4201 is described per the block diagram of Figure 2 and is divided into six sections:
•
USB DEVICE
•
USB TRANSCEIVER
•
VOLTAGE REFERENCE
•
ANALOG I/O
•
POWER CONTROL
•
OSCILLATORS
The following sections provide details regarding the operation of each of these elements. Additionally,
APPENDIX C provides recommended connection information.
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USB defined descriptors are passed to the host from the DS4201; these are used to communicate what
capabilities and features are supported by the DS4201 as well as device characteristics. Contact Dallas
Semiconductor for additional device descriptor documentation.
USB DEVICE OPERATION
As shown in Figure 1 and Figure 2, within the USB Device block resides the sigma–delta D/A converter
for audio data playback, level adjustments for the D/A, microphone, and auxiliary signal paths, and
mixing of the three signal channels to a single line output channel. Organization and control of these
elements as well as the interface to the host controller in an USB Audio Device Class (ADC) framework
is shown in Figure 3. This structure provides all the capabilities for the host system to communicate with
and operate the various features within the DS4201. As shown in Figure 3, theDS4201 USB device
structure will consist of one default device configuration, one AUDIO CONTROL interface, and one
AUDIO STREAMING interface. The details of these interfaces are provided in the following para-
graphs.
OPERATIONAL BLOCK DIAGRAM Figure 2
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USB DEVICE STRUCTURE Figure 3
NOTE:
For the audio streaming interface alternate setting which selects adaptive synchronization, the
isochronous synch pipe at endpoint 2 (EP2) does not exist.
AUDIO CONTROL INTERFACE
The CONTROL interface is used by the USB host to manipulate and monitor the operation of the
DS4201. Additionally, all features, control capabilities, and characteristics of the DS4201 are
communicated to the host through USB descriptors over this interface. Host communication with the
CONTROL interface is performed over a default control pipe at Endpoint 0.
The USB Audio Device Class (ADC) specification defines audio function units and terminals to describe
and operate a USB Audio device; the Endpoint 0 default control pipe is used to control the units and
terminals. USB operation of the DS4201 Audio device is controlled through Feature Units (FU), a Mixer
Unit (MU), Input Terminals (IT), an Extension Unit (XU), and an Output Terminal (OT) as shown in
Figure 3. The Input Terminal associated with the STREAMING INTERFACE makes a logical connection
to the isochronous data pipe feeding PCM coded data to the DS4201 at Endpoint 1. The DS4201
performs D/A processing of the incoming digital PCM data at this point and thus the output from this
Input Terminal is a logical cluster of analog audio signals consisting of the left and right audio channels.
The Input Terminals associated with the Auxiliary (AUX) and Microphone (MIC) inputs are for
connection to the analog line inputs; the output from these terminals are logical clusters of the respective
analog audio input source. The three Feature Units (FU) provide Mute capability for the three analog
audio clusters. The Extension Unit (XU) provides a DS4201 specific control capability which can be used
to select between two output level ranges from the sigma–delta D/A converter. The Mixer Unit (MU)
provides control for level setting and mixing of the three analog audio clusters; the control capability
consists of gain or attenuation to the incoming analog signals prior to mixing the left and right composite
channels.
INPUT TERMINALS
The ADC Input Terminal (IT) is used to receive audio information into the audio function. It also
converts the incoming audio stream into the separate logical channels embedded. USB OUT endpoints as
well as analog audio inputs are supported. The DS4201 uses three ITs: IT:TID1 connects to Endpoint 1
carrying a USB isochronous audio stream, IT:TID2 connects to the analog AUX input, and IT:TID3
connects to the analog MIC input.
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