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DESCRIPTION
The WM8721 is a low power stereo DAC with an integrated
headphone driver. The WM8721 is designed specifically for
portable MP3 audio and speech players. The WM8721 is
also ideal for MD, CD machines and DAT players.
Stereo 24-bit multi-bit sigma delta DACs are used with
oversampling digital interpolation filters. Digital audio input
word lengths from 16-32 bits and sampling rates from 8kHz
to 96kHz are supported.
Stereo audio outputs are buffered for driving headphones
from a programmable volume control, line level outputs are
also provided along with anti-thump mute and power
up/down circuitry.
The device is controlled via a 2 or 3 wire serial interface.
The interface provides access to all features including
volume controls, mutes, de-emphasis and extensive power
management facilities. The device is available in a small 20-
pin SSOP package.
A USB mode is provided where all audio rates can be
derived from a simple 12MHz or 24MHz master clock,
eliminating the need for a PLL or multiple crystals.
WM8721
Internet Audio DAC with Integrated Headphone Driver
FEATURES
•
Audio Performance
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DAC SNR 100dB (‘A’ weighted) at AVDD = 3.3V
−
1.42 – 3.6V Digital Supply Operation
−
2.7 – 3.6V Analogue Supply Operation
Low Power
−
Headphone Playback: 20mW at AVDD = 3.3V
DAC Sampling Frequency: 8kHz – 96kHz
2 or 3-Wire MPU Serial Control Interface
Programmable Audio Data Interface Modes
−
I
2
S, Left, Right Justified or DSP
−
16/20/24/32 bit Word Lengths
Stereo Audio Outputs
Output Volume and Mute Controls
Highly Efficient Headphone Driver
20-Pin SSOP Package
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APPLICATIONS
•
•
Portable MP3 Players
CD and Minidisc Players
BLOCK DIAGRAM
MODE
SCLK
SDIN
CSB
AGND
AVDD
VMID
W
WM8721
HPVDD
CONTROL INTERFACE
HPGND
+6 to -73dB
1 dB Steps
VOL/
MUTE
H/P
DRIVER
RHPOUT
DIGTAL AUDIO INTERFACE
DACDAT
DAC
DIGITAL
FILTERS
MUTE
ROUT
DACLRC
LOUT
DAC
MUTE
VOL/
MUTE
CLKIN
DIVIDER
(Div x1,
x2)
BCLK
H/P
DRIVER
LHPOUT
+6 to -73dB
1 dB Steps
DCVDD
(1.5V)
DBVDD
(3.3V)
DGND
WOLFSON MICROELECTRONICS plc
MCLK
Production Data, November 2004, Rev 4.0
www.wolfsonmicro.com
Copyright
2004
Wolfson Microelectronics plc
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
