DS4201.PDF

DS4201

USB Audio DAC

FEATURES

•

PIN ASSIGNMENT

Fully USB Core Class v1.0 Compliant

DGND

SPM

X2I

X2O

DGND

X1I

X1O

D–

D+

•

Fully USB Audio Device Class v1.0 Compliant

SUSO

VCM

VREFI

AGND

LOUT

ROUT

LMIC

RMIC

LAUX

RAUX

•

Complete Stereo DAC System

•

16–bit SD 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

DGND

•

High Rate 12 Mbps USB Interface

28–PIN DIP (600 MIL)

•

Analog Output Mixing for Auxiliary Inputs

•

Multiple Power Configurations Including Completely

USB Powered

•

3.3V – 5.0V Operating Range

SPM

X2I

X2O

DGND

X1I

X1O

VCM

VREFI

AGND

LOUT

ROUT

ORDERING INFORMATION

Part Number

Description

DS4201

28–pin DIP

DS4201F

44–pin QFP

44–PIN QFP (10mm x10mm)

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 pro-

cessing, 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

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DS4201

of line and microphone inputs provide legacy and hybrid

speaker capabilities.

generation PC system and audio standards put forth by

industry leaders.

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

RELATED DOCUMENTS

This data sheet references or complies with the follow-

ing 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

V B

V D

DGND AGND

V A VREFI VCM

X1I

X1O

X2I

X2O

SPM

POWER

VOLTAGE

REFERENCE

OSCILLATORS

POWER

MANAGEMENT

SUSO

LEFT

FIFO

194 BYTES

16–BIT

D/A

ATTN/MUTE

LOUT

D+

D–

USB

XCVR

USB

DEVICE

CORE

RIGHT

FIFO

194 BYTES

16–BIT

ATTN/MUTE

ROUT

D/A

DEVICE

CONTROL

ATTN/MUTE

LAUX

RAUX

ATTN/MUTE

LMIC

RMIC

SIGNAL SUMMARY

SIGNAL NAME TYPE FUNCTION

D+

I/O

USB data – non–inverted signal of differential data pair.

D–

I/O

USB data – inverted signal of differential data pair.

SPM

Suspend Power Mode – controls device power configuration when a USB suspend

state is entered.

SUSO

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.

RMIC

Microphone right channel analog input to the analog output mixer.

LMIC

Microphone left channel analog input to the analog output mixer.

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DS4201

SIGNAL SUMMARY Cont’d

SIGNAL NAME TYPE FUNCTION

RAUX

Auxiliary right channel analog input to the analog output mixer.

LAUX

Auxiliary left channel analog input to the analog output mixer.

ROUT

Right channel analog audio output from the mixer, 0.5 V RMS or 1.0 V RMS centered

about V REF .

LOUT

Left channel analog audio output from the mixer, 0.5 V RMS or 1.0 V RMS centered

about V REF .

VCM

DC bias point to which all AC coupled inputs are centered. Nominally V REF = 0.4 x

VA.

VREFI

Filter capacitor connection for internal voltage reference node. Connect a 10 m F and

0.1 m F 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.

DGND

Digital ground.

AGND

Analog ground.

X1I

Crystal 1 input. Use a 12.0 MHz, fundamental mode, parallel resonant crystal. A 12.0

MHz CMOS clock source may also be used.

X1O

Crystal 1 output. Connect to other side of crystal 1 if used.

X2I

Crystal 2 input. Use a 12.288 MHz, fundamental mode, parallel resonant crystal. A

12.288 MHz CMOS clock source may also be used.

X2O

Crystal 2 output. Connect to other side of crystal 2 if used.

No connect. Leave these pins unconnected.

DS4201 OPERATION

Operation of the DS4201 is described per the block dia-

gram 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.

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, the

DS4201 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.

USB defined descriptors are passed to the host from the

DS4201; these are used to communicate what capabili-

ties and features are supported by the DS4201 as well

as device characteristics. Contact Dallas Semiconduc-

tor for additional device descriptor documentation.

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DS4201

OPERATIONAL BLOCK DIAGRAM Figure 2

V D

DGND AGND

V A

X1I

X1O

X2I

X2O

VREFI VCM

SPM

POWER

OSCILLATORS

VOLTAGE

REFERENCE

POWER

CONTROL

V B

12.0 MHz

12.288 MHz

VREF

SHDN

D+

USB

XCVR

D–

SUSO

GND

USB

DEVICE

LAUX

RAUX

LOUT

ROUT

LMIC

RMIC

USB DEVICE STRUCTURE Figure 3

USB HOST

DS4201 USB DEVICE

Default Pipe

EP0

AUDIO CONTROL INTERFACE

SYSTEM

S/W

AUDIO STREAMING

INTERFACE

EP1

Isochronous

Data Out Pipe

Isochronous

Synch Pipe

(See Note)

USB PHYSICAL I/F

UID9

AUDIO

CLIENT

EP2

TID1

LINE OUT

UID5

TID4

UID8

AUX IN

TID2

UID6

MIC IN

TID3

UID7

NOTE: FOR THE AUDIO STREAMING INTERFACE ALTERNATE SETTING WHICH SELECTS ADAPTIVE SYNCHRONIZATION,

THE ISOCHRONOUS SYNCH PIPE AT ENDPOINT 2 (EP2) DOES NOT EXIST.

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DS4201

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 char-

acteristics of the DS4201 are communicated to the host

through USB descriptors over this interface. Host com-

munication with the CONTROL interface is performed

over a default control pipe at Endpoint 0

audio inputs are supported. The DS4201 uses three

ITs: IT:TID1 connects to Endpoint 1 carrying a USB iso-

chronous audio stream, IT:TID2 connects to the analog

AUX input, and IT:TID3 connects to the analog MIC

input.

Extension Unit

The Extension Unit (XU) is used to add vendor specific

features to a USB audio function. The XU in the

DS4201, XU:UID9, is used to select between two avail-

able output ranges for the sigma–delta DAC: 1.414 VPP

or 2.828 V PP . The XU control parameter, OUT-

PUT_DOUBLE_CONTROL, is used to select or enable

the output range mode. When set TRUE, the 2.828 V PP

range is selected; when FALSE, the 1.414 V PP range is

selected. When the DS4201 is operating from a 3V

power source, the 1.414 V PP range must be selected.

For 5V operation, either range can be used. The com-

mand and control parameter used for the XU SET/GET

request is defined in APPENDIX A.

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 feed-

ing PCM coded data to the DS4201 at Endpoint 1. The

DS4201 performs D/A processing of the incoming digi-

tal 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 ana-

log line inputs; the output from these terminals are log-

ical 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 chan-

nels.

Extension Unit Default Setting

The power–on default setting of the XU is:

OUTPUT_DOUBLE_SELECTOR = FALSE

(DAC output range = 1.414 V PP )

Feature Units

As defined by the ADC specification, the Feature Unit

(FU) provides basic property control of an audio signal.

The FU descriptor reports what controls exist for each

channel that passes through the FU as well as a master

control. All FUs have a single input and output pin for the

audio cluster being controlled. The audio cluster can

contain multiple logical channels (left, right, etc.) which

are individually or group controlled by FU commands.

As shown in Figure 3, FU:UID5 operates on the cluster

from XU:UID9, FU:UID6 operates on the cluster from

IT:TID2, and FU:UID7 operates on the cluster from

IT:TID3. Table 1 lists the cluster channels and proper-

ties supported by each FU. As shown in the table,

MUTE is the only control property supported by the

DS4201 FUs. FU commands are documented in

APPENDIX A.

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 chan-

nels embedded. USB OUT endpoints as well as analog

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