WM8608 Datasheet, PDF (15/54 Pages) Wolfson Microelectronics plc – 5 TO 7.1 CHANNEL PWM CONTROLLER

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WM8608
DEVICE DESCRIPTION
INTRODUCTION
SIGNAL PATH
The WM8608 is a high-performance multi-channel Pulse-Width Modulation (PWM) digital power
amplifier controller. The device accepts up to 7.1 channels of audio in PCM input format, and outputs
six PWM full-bandwidth channels, plus a PWM sub-woofer channel. The outputs are suitable for
directly driving integrated switching output stages available from a number of vendors. The device is
also compatible with discrete MOSFET output stages. In both cases, Wolfson Microelectronics offer
Reference Designs for complete PWM digital power amplifiers, providing high-performance low-cost
solutions ideal for Surround Sound AV Processors and DVD Receivers.
The WM8608 has a configurable input processor which accepts either Stereo, 5.1, 6.1 or 7.1
channels of PCM audio and outputs Stereo, 2.1, 5.1 or 6.1 outputs. This is done by mixing rear
channel data into centre rear or surround output channels, as required. If 5.1 channel data is input,
the surround data may be processed to create the rear-centre output.
The device has a Bass Management function, which has low-pass and high-pass filters for feeding
the sub channel and main output channels. It also provides selectable boost for the LFE channel.
Each channel can be configured to drive either “large” full-range speakers or “small” satellite
speakers with limited bass capability.
A Tone Control function is provided, plus selectable high frequency equalisation to compensate for
different loudspeaker characteristics. Independent volume control is provided for all channels, with
comprehensive mute features.
A Dynamic Peak Compressor with programmable attack and decay times is included, which allows
headroom for tone control, bass management and extra digital gain to be provided, without clipping
occurring.
The device is controlled via a 2/3 wire serial interface. The interface provides access to all features
including channel selection, volume controls, mute, de-emphasis and power management facilities.
The WM8606 receives digital input data via an 8-channel digital audio interface. The data is
processed in turn by the Input Processor, Bass Management and Equalisation, Volume Control and
Dynamic Peak Compressors, Interpolation Filters, and PCM-PWM Converters, as shown in Figure 7.
The PWM signals are output via selectable LVDS/CMOS drivers.
8 Channel Input
Input Processor
Bass Management and
Equalisation
Volume Control / Dynamic
Peak Compressors
Interpolation Filters
PCM - PWM Converter
CMOS / LVDS Output
Figure 7 Signal Processing Block Diagram
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PP Rev 1.5 March 2004
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