WM8721
w
Internet Audio DAC with Integrated Headphone Driver
DESCRIPTION
FEATURES
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Audio Performance
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.
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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
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.
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Low Power
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Headphone Playback: 20mW at AVDD = 3.3V
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DAC Sampling Frequency: 8kHz – 96kHz
2 or 3-Wire MPU Serial Control Interface
Programmable Audio Data Interface Modes
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.
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I2S, Left, Right Justified or DSP
16/20/24/32 bit Word Lengths
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Stereo Audio Outputs
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.
Output Volume and Mute Controls
Highly Efficient Headphone Driver
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.
APPLICATIONS
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•
Portable MP3 Players
CD and Minidisc Players
BLOCK DIAGRAM
W
HPVDD
HPGND
WM8721
CONTROL INTERFACE
+6 to -73dB
1 dB Steps
H/P
DRIVER
VOL/
MUTE
RHPOUT
MUTE
DAC
DAC
DACDAT
ROUT
LOUT
DIGITAL
FILTERS
DACLRC
BCLK
MUTE
VOL/
MUTE
H/P
DRIVER
LHPOUT
CLKIN
DIVIDER
(Div x1,
x2)
+6 to -73dB
1 dB Steps
WOLFSON MICROELECTRONICS plc
Production Data, November 2004, Rev 4.0
Copyright 2004 Wolfson Microelectronics plc
www.wolfsonmicro.com