WM9705_06 Datasheet, PDF (16/55 Pages) Wolfson Microelectronics plc – Multimedia AC’97 CODEC with Integrated Touch Screen Controller

WM9705
DEVICE DESCRIPTION
Production Data
INTRODUCTION
This specification describes the WM9705 audio codec, which is designed to be software and
hardware compatible with the Intel AC’97 rev2.2 component specification. The device is a
derivative of the basic AC’97 codec, with added support for resistive touch-screen pen inputs.
Variable Rate Audio (VRA) is supported at rates defined in the Intel rev2.1 or rev2.2 specification,
and a SPDIF output port is provided which may optionally be used to output the PCM DAC
information to external processors. A key feature of operation of the pen digitiser function is the
cessation of screen drive activity when the pen is lifted from the screen, so minimising audio
performance degradation and reducing power consumption.
WM9705 offers the following features:
Stereo Audio Codec with Intel specified VRA support of different audio sample rates
Pen Digitiser function with 4-wire pen interface and support for pen-down detection, pen pressure
measurement and wake-on-pen-down.
Auxiliary ADC inputs for temperature, supply and battery monitoring.
Pen-down flag and ADC BUSY flags, output to pins, and MASK input pin provided to allow delay
of pen conversions in event of LCD activity
Optional SPDIF and I²S audio outputs (SPDIF output may be hardware enabled so needing no
driver support)
Headphone drive capability and optional auto detection of headset or headphone plug in
It is highly recommended that the Intel AC’97 rev2.2 specification be studied in parallel with this
document: This specification can be downloaded from the Intel web site.
The WM9705 is fully operable on 3V or 5V or mixed 3/5V supplies, and is packaged in the
industry standard 48pin TQFP package with 7mm body size.
Figure 10 shows the functional block diagram including control register bit locations for WM9705.
AC’97 FEATURES
WM9705 implements the base set of AC’97 rev2.2 features, plus several enhancements:
All rev2.2 specified variable audio sample rates supported
3-D stereo enhancement feature.
Headphone support on AUX outputs (pins 39,41)
Primary/secondary codec operation by pin programming of CID0 pin
SPDIF audio output with rev2.2 compliant control set.
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PD Rev 4.4 August 2006
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