WM8721_04 Datasheet, PDF (1/37 Pages) Wolfson Microelectronics plc – Internet Audio DAC with Integrated Headphone Driver

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WM8721
Internet Audio DAC with Integrated Headphone Driver
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.
BLOCK DIAGRAM
FEATURES
• Audio Performance
− 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
− I²S, 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
APPLICATIONS
• Portable MP3 Players
• CD and Minidisc Players
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WM8721
CONTROL INTERFACE
DACDAT
DACLRC
BCLK
DIGITAL
FILTERS
CLKIN
DIVIDER
(Div x1,
x2)
DAC
DAC
MUTE
+6 to -73dB
1 dB Steps
VOL/
MUTE
H/P
DRIVER
MUTE
VOL/
MUTE
+6 to -73dB
1 dB Steps
H/P
DRIVER
HPVDD
HPGND
RHPOUT
ROUT
LOUT
LHPOUT
WOLFSON MICROELECTRONICS plc
www.wolfsonmicro.com
Production Data, November 2004, Rev 4.0
Copyright 2004 Wolfson Microelectronics plc