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WM8978
Stereo CODEC with Speaker Driver
DESCRIPTION
FEATURES
The WM8978 is a low power, high quality stereo CODEC
designed for portable applications such as multimedia phone,
digital still camera or digital camcorder.
Stereo CODEC:
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DAC SNR 98dB, THD -84dB (‘A’ weighted @ 48kHz)
•
ADC SNR 95dB, THD -84dB (‘A’ weighted @ 48kHz)
•
On-chip Headphone Driver with ‘capless’ option
40mW per channel into 16Ω / 3.3V SPKVDD
•
1W output power into 8Ω BTL speaker / 5V SPKVDD
Capable of driving piezo speakers
Stereo speaker drive configuration
Mic Preamps:
•
Stereo Differential or mono microphone Interfaces
Programmable preamp gain
Psuedo differential inputs with common mode
rejection
Programmable ALC / Noise Gate in ADC path
•
Low-noise bias supplied for electret microphones
Other Features:
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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’
•
On-chip PLL supporting 12, 13, 19.2MHz and other clocks
•
Support for 8, 11.025, 12, 16, 22.05, 24, 32, 44.1 and
48kHz sample rates
•
Low power, low voltage
2.5V to 3.6V (digital: 1.71V to 3.6V)
•
5x5mm 32-lead QFN package
The device integrates preamps for stereo differential mics, and
includes drivers for speakers, headphone and differential or
stereo line output. External component requirements are
reduced as no separate microphone or headphone amplifiers
are required.
Advanced on-chip digital signal processing includes a 5-band
equaliser, a mixed signal Automatic Level Control for the
microphone or line input through the ADC as well as a purely
digital limiter function for record or playback. Additional digital
filtering options are available in the ADC path, to cater for
application filtering such as ‘wind noise reduction’.
The WM8978 digital audio interface can operate as a master or
a slave. An internal PLL can generate all required audio clocks
for the CODEC from common reference clock frequencies, such
as 12MHz and 13MHz.
The WM8978 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. The speaker outputs and OUT3/4 line
outputs can run from a 5V supply if increased output power is
required. Individual sections of the chip can also be powered
down under software control.
BLOCK DIAGRAM
APPLICATIONS
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WOLFSON MICROELECTRONICS plc
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Stereo Camcorder or DSC
Multimedia Phone
Production Data, June 2009, Rev 4.4
Copyright ©2009 Wolfson Microelectronics plc
