WM8731_06 Datasheet, PDF (1/63 Pages) Wolfson Microelectronics plc – Portable Internet Audio CODEC with Headphone Driver and Programmable Sample Rates

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WM8731 / WM8731L
Portable Internet Audio CODEC with Headphone Driver
and Programmable Sample Rates
DESCRIPTION
The WM8731 or WM8731L (WM8731/L) are low power
stereo CODECs with an integrated headphone driver. The
WM8731/L is designed specifically for portable MP3 audio
and speech players and recorders. The WM8731 is also
ideal for MD, CD-RW machines and DAT recorders.
Stereo line and mono microphone level audio inputs are
provided, along with a mute function, programmable line
level volume control and a bias voltage output suitable for
an electret type microphone.
Stereo 24-bit multi-bit sigma delta ADCs and DACs are
used with oversampling digital interpolation and decimation
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 28-
lead SSOP package or the smaller 28 lead quad flat
leadless package (QFN).
BLOCK DIAGRAM
FEATURES
• Highly Efficient Headphone Driver
• Audio Performance
- ADC SNR 90dB (‘A’ weighted) at 3.3V, 85dB at 1.8V
- DAC SNR 100dB (‘A’ weighted) at 3.3V, 95dB at 1.8V
• Low Power
- Playback only 22mW, 8mW (‘L’ Variant)
- Analogue Pass Through 12mW, 3.5mW (‘L’ variant)
- 1.42 – 3.6V Digital Supply Operation
- 2.7 – 3.6V Analogue Supply Operation
- 1.8 – 3.6V Analogue Supply Operation (‘L’ Variant)
• ADC and DAC Sampling Frequency: 8kHz – 96kHz
• Selectable ADC High Pass Filter
• 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
- Master or Slave Clocking Mode
• Microphone Input and Electret Bias with Side Tone Mixer
• Available in 28-lead SSOP or 28-lead QFN package
APPLICATIONS
• Portable MP3 Players and Recorders
• CD and Minidisc Recorders
• PDAs / smartphones
AVDD
VMID
AGND
MICBIAS
RLINEIN
MICIN
VOL
+12 to -34.5dB, 1.5dB
Steps
0dB/
20dB
LLINEIN
VOL
+12 to -34.5dB, 1.5dB
Steps
MUTE
MUTE
MUX
MUTE
MUTE
MUX
ADC
ADC
OSC
CLKIN
DIVIDER
(Div x1, x2)
CLKOUT
DIVIDER
(Div x1, x2)
CONTROL INTERFACE
DIGITAL
FILTERS
DAC
DAC
DIGTAL AUDIO INTERFACE
Bypass
MUTE
ATTEN/
MUTE
Side Tone
MUTE
Σ
MUTE
Σ
Side Tone
ATTEN/
MUTE
MUTE
Bypass
W
WM8731
+6 to -73dB
1 dB Steps
VOL/
MUTE
H/P
DRIVER
VOL/
MUTE
+6 to -73dB
1 dB Steps
H/P
DRIVER
HPVDD
HPGND
RHPOUT
ROUT
LOUT
LHPOUT
WOLFSON MICROELECTRONICS plc
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Production Data, August 2006, Rev 4.3
Copyright ©2006 Wolfson Microelectronics plc