UAC 3552A
PRELIMINARY DATA SHEET
2
Micronas
Contents
Page
Section
Title
4
1.
Introduction
5
1.1.
Features
6
2.
Functional Description
6
2.1.
Hardware
6
2.1.1.
USB Interface
6
2.1.1.1.
Transceiver
6
2.1.1.2.
Interface Engine
6
2.1.1.3.
Microcontroller
6
2.1.2.
Audio Control Interface
6
2.1.3.
Audio Streaming Interface
6
2.1.4.
Audio Processing Unit
6
2.1.5.
Analog Back-end
7
2.1.5.1.
DAC
8
2.1.5.2.
Analog Low-pass
8
2.1.5.3.
Postfilter Op Amps
8
2.1.5.4.
Input Mixer
9
2.1.5.5.
Analog Volume Control
9
2.1.5.6.
Line-out/Headphone Amplifier
9
2.1.6.
General Purpose I/O
10
2.1.7.
Special I/O
10
2.1.7.1.
SOF (Start of Frame)
10
2.1.7.2.
AUXEN
10
2.1.7.3.
SUSPEND
10
2.1.8.
Clock System
10
2.2.
Software
10
2.2.1.
USB Microcontroller Software
10
2.2.1.1.
Chapter 9 Functions
10
2.2.1.2.
Device Descriptor
10
2.2.1.3.
String Descriptor
11
2.2.1.4.
HID Report Descriptor
11
2.2.2.
Audio Processing Software
11
2.2.2.1.
Sample Rate Converter
11
2.2.2.2.
Automatic Gain Control
12
2.2.2.3.
Bass Control
12
2.2.2.4.
Treble Control
13
2.2.2.5.
Bass Boost Control
13
2.2.2.6.
Parametric Equalizer
13
2.2.2.7.
Volume and Balance Control
13
2.2.3.
Mute Control
13
2.2.3.1.
Oversampling
Contents, continued
Page
Section
Title
PRELIMINARY DATA SHEET
UAC 3552A
Micronas
3
14
3.
Specifications
14
3.1.
Outline Dimensions
14
3.2.
Pin Connections and Short Descriptions
16
3.3.
Pin Descriptions
16
3.3.1.
Power Supply Pins
16
3.3.2.
Analog Audio Pins
17
3.3.3.
Other Pins
17
3.4.
Pin Configuration
18
3.5.
Pin Circuits
19
3.6.
Electrical Characteristics
19
3.6.1.
Absolute Maximum Ratings
20
3.6.2.
Recommended Operating Conditions
22
3.6.3.
Characteristics
26
4.
Applications
26
4.1.
Recommended Low-Pass Filters for Analog Outputs
27
4.2.
Typical Application
28
5.
Data Sheet History
UAC 3552A
PRELIMINARY DATA SHEET
4
Micronas
Universal Serial Bus DAC
1. Introduction
The UAC 3552A is the first member of Micronas' USB
audio controller family of ICs targeting a wide variety of
audio applications on the USB. The UAC 3552A is a
single-chip, high-precision digital-to-analog audio con-
verter. It includes a high-quality audio sample rate con-
verter and is able to support a wide range of sample
rates, as well as different audio formats.
The IC contains a complete USB transceiver that
allows direct connection to the USB. An on-chip
EEPROM allows storing of manufacturer-specific data
or product identification. The EEPROM can be pro-
grammed directly via the USB.
Baseband audio processing is handled by an internal,
powerful DSP. Apart from basic audio features, like
tone and volume control, there is enough processing
power left to realize customer-specific applications.
The audio DAC uses Micronas' proprietary multibit
sigma-delta technique. It features very low sensitivity
to clock jitter, high linearity, and a superior S/N ratio.
The UAC 3552A provides an on-chip headphone/
speaker amplifier. Moreover, mixing additional analog
audio sources to the D/A-converted signal is sup-
ported.
The IC is designed for all kinds of USB audio applica-
tions, such as USB active speakers, USB headphones,
and USB interfaces to home stereo equipment, etc.
Any existing analog speaker set can easily be
upgraded to USB by just including the UAC 3552A
according to the application circuit on page 27. No
software development is required, because all drivers
are already part of the operating system which sup-
ports USB (e. g. WindowsTM 98).
Fig. 11: Block diagram of the UAC 3552A
D+
D
-
OUTL
OUTR
DAC
Input
Select
USB
and
Mixing
Interface
DSP
Analog Input
Volume
and
Headphone
Amplifier
+5 V GND
HID IO
External Loop-through Filter
ROM
ROM
EEPROM
PRELIMINARY DATA SHEET
UAC 3552A
Micronas
5
1.1. Features
single-chip, USB specification 1.0/1.1 compliant,
stereo audio D/A converter
12-Mbit/s USB transceiver
adaptive isochronous endpoint for USB Audio
USB-programmable vendor IDs (1024-bit EEPROM
on chip)
four general purpose input pins and four output pins
(human interface pins)
customizable I/O functionality by download-software
supports 16-bit mono/stereo and 24-bit stereo audio
data
adaptive sample rate converter for 5 to 50 kHz input
sampling rate
audio baseband control: bass, treble, volume, and
balance, additional analog volume, mute
bass boost
automatic gain control (AGC)
"PerfectSpeaker" digital speaker equalizer
THD better than 0.01 %, SNR of 96 dB
integrated low-power stereo headphone amplifier
on-chip op amps for external analog filter
analog stereo input (AUX) with source selection and
mixing
single 5-V power supply
Fig. 12: System application diagram
UAC
Active Stereo Speakers
Headphones
Stereo Equipment
USB
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