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DESCRIPTION
The WM8985 is a low power, high quality, feature-rich stereo
codec designed for portable multimedia applications that require
low power consumption and high quality audio.
The device integrates preamps for stereo differential mics, and
includes class D and class AB drivers for headphone and
differential or stereo line output. External component
requirements are reduced as no separate microphone or
headphone amplifiers are required.
Advanced DSP features include a 5-band equaliser, an
ALC/limiter for the microphone or line input through the ADC
and a digital playback limiter. Additional digital filtering options
are available in the ADC path, to cater for application filtering
such as ‘wind noise reduction’ and a programmable notch filter.
Highly flexible mixers enable many new application features,
with the option to record and playback any combination of voice,
line inputs and digital audio such as FM Radio or MP3.
The WM8985 digital audio interface can operate in master or
slave mode, while an integrated PLL provides flexible clocking
schemes.
The WM8985 operates at analogue supply voltages from 2.5V
to 3.3V, although the digital core can operate at voltages down
to 1.71V to save power. Additional power management control
enables individual sections of the chip to be powered down
under software control.
WM8985
Multimedia CODEC With Class D Headphone and Line Out
FEATURES
Stereo Codec:
•
DAC SNR 98dB, THD -86dB (‘A’ weighted @ 48kHz)
•
ADC SNR 92.5dB, THD -75dB (‘A’ weighted @ 48kHz)
•
Headphone driver with ‘capless’ option
•
40mW/channel output power into 16Ω / 3.3V AVDD2
•
Class D headphone driver
•
Class AB headphone / line Driver
•
PSRR 70dB at 217Hz
•
Stereo, mono or differential line output
Mic Preamps:
•
Stereo differential or mono microphone interfaces
•
Programmable preamp gain
•
Pseudo differential inputs with common mode rejection
•
Programmable ALC / Noise Gate in ADC path
•
Low-noise bias supplied for electret microphones
Other Features:
•
Enhanced 3-D function for improved stereo separation
•
Digital playback limiter
•
5-band Equaliser (record or playback)
•
Programmable ADC High Pass Filter (wind noise reduction)
•
Programmable ADC Notch Filter
•
Aux inputs for stereo analog input signals or ‘beep’
•
PLL supporting various clocks between 8MHz-50MHz
•
Sample rates supported (kHz): 8, 11.025, 16, 12, 16, 22.05,
24, 32, 44.1, 48
•
Low power, low voltage
•
2.5V to 3.6V analogue supplies
•
1.71V to 3.6V digital supplies
•
5x5mm 32-lead QFN package
APPLICATIONS
•
•
Portable audio player / FM radio
Multimedia Mobile Handsets
WOLFSON MICROELECTRONICS plc
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Pre-Production, October 2006, Rev 3.4
Copyright
©2006
Wolfson Microelectronics plc
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
