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Mono CODEC with Speaker Driver
DESCRIPTION
The WM8974 is a low power, high quality mono codec
designed for portable applications such as Digital Still Camera
or Digital Voice Recorder.
The device integrates support for a differential or single ended
mic, and includes drivers for speakers or headphone, and
mono line output. External component requirements are
reduced as no separate microphone or headphone amplifiers
are required.
Advanced Sigma Delta Converters are used along with digital
decimation and interpolation filters to give high quality audio at
sample rates from 8 to 48ks/s. Additional digital filtering
options are available in the ADC path, to cater for application
filtering such as ‘wind noise reduction’, plus an advanced
mixed signal ALC function with noise gate is provided.
An on-chip PLL is provided to generate the required Master
Clock from an external reference clock. The PLL clock can
also be output if required elsewhere in the system.
The WM8974 operates at supply voltages from 2.5 to 3.6V,
although the digital core can operate at voltages down to
1.62V to save power. The speaker and mono outputs use a
separate supply of up to 5V which enables increased output
power if required. Different sections of the chip can also be
powered down under software control by way of the selectable
two or three wire control interface.
WM8974 is supplied in a very small 4x4mm QFN package,
offering high levels of functionality in minimum board area,
with high thermal performance.
WM8974
FEATURES
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Mono Codec:
Audio sample rates:8, 11.025, 16, 22.05, 24, 32, 44.1, 48kHz
DAC SNR 98dB, THD -84dB (‘A’-weighted @ 8 – 48ks/s)
ADC SNR 90dB, THD -80dB (‘A’-weighted @ 8 – 48ks/s)
On-chip Headphone/Speaker Driver with ‘cap-less’ connect
- 40mW output power into 16Ω / 3.3V SPKRVDD
- BTL speaker drive 0.9W into 8Ω / 5V SPKRVDD
Additional MONO Line output
Multiple analog or ‘Aux’ inputs, plus analog bypass path
Mic Preamps:
Differential or single end Microphone Interface
- Programmable preamp gain
- Psuedo differential inputs with common mode rejection
- Programmable ALC / Noise Gate in ADC path
Low-noise bias supplied for electret microphones
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OTHER FEATURES
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5 band EQ (record or playback path)
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Digital Playback Limiter
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Programmable ADC High Pass Filter (wind noise reduction)
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Programmable ADC Notch Filter
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On-chip PLL
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Low power, low voltage
- 2.5V to 3.6V (digital core: 1.62V to 3.6V)
- power consumption <10mA all-on 48ks/s mode
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4x4x0.9mm 24 pin QFN package
APPLICATIONS
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Digital Still Camera Audio Codec
General Purpose low power audio CODEC
WOLFSON MICROELECTRONICS plc
www.wolfsonmicro.com
Product Preview, September 2004, Rev 1.1
Copyright
2004
Wolfson Microelectronics plc
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
