WM8980GEFLSLASHV datasheet(16/81 Pages) WOLFSON

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WM8980

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PP Rev 1.6 January 2005

OUT3 and OUT4 can be configured to provide an additional stereo lineout from the output of the

DACs, the mixers or the input microphone boost stages. Alternatively OUT4 can be configured as a

mono mix of left and right DACs or mixers, or simply a buffered version of the chip midrail reference

voltage. OUT3 can also be configured as a buffered VMID output. This voltage may then be used as

a headphone ‘pseudo ground’ allowing removal of the large AC coupling capacitors often used in the

output path.

AUDIO INTERFACES

The WM8980 has a standard audio interface, to support the transmission of stereo data to and from

the chip. This interface is a 3 wire standard audio interface which supports a number of audio data

formats including I2S, DSP/PCM Mode (a burst mode in which LRC sync plus 2 data packed words

are transmitted), MSB-First, left justified and MSB-First, right justified, and can operate in master or

slave modes.

CONTROL INTERFACES

To allow full software control over all its features, the WM8980 offers a choice of 2 or 3 wire MPU

control interface. It is fully compatible and an ideal partner for a wide range of industry standard

microprocessors, controllers and DSPs.

Selection between the modes is via the MODE pin. In 2 wire mode the address of the device is fixed

as 0011010.

CLOCKING SCHEMES

WM8980 offers the normal audio DAC clocking scheme operation, where 256fs MCLK is provided to

the DAC and ADC.

A PLL is included which may be used to generate these clocks in the event that they are not

available from the system controller. This PLL uses an input clock, typically the 12MHz USB or ilink

clock, to generate high quality audio clocks. If this PLL is not required for generation of these clocks,

it can be reconfigured to generate alternative clocks which may then be output on the GPIO pins and

used elsewhere in the system.

VIDEO BUFFER

The WM8980 incorporates a current mode output video buffer with an input 3

rd order Low Pass Filter

(LPF) and clamp. The gain through this buffer can be programmed as 0dB or 6dB via the control

interface. The current mode output means that the signal swing seen at the output of the buffer will

be the same as that at the connection to the receiving equipment (e.g. a TV). Note that the input to

the receiver should be AC coupled and terminated to 75

Ω, as is standard, for best performance.

POWER CONTROL

The design of the WM8980 has given much attention to power consumption without compromising

performance. It operates at very low voltages, and includes the ability to power off any unused parts

of the circuitry under software control, and includes standby and power off modes.

OPERATION SCENARIOS

Flexibility in the design of the WM8980 allows for a wide range of operational scenarios, some of

which are proposed below:

Stereo Camcorder; The provision of two stereo microphone preamplifiers, allows support for both

internal and external microphones. All drivers for speaker, headphone and line output connections

are integrated. The selectable ‘application filters’ after the ADC provide for features such as ‘wind

noise’ reduction, or mechanical noise reducing filters.

The integrated video buffer allows direct

connection to a TV or VCR for both video and audio (via line outputs).

Stereo Digital still camera recording; Support for digital stereo video with audio recording is similar to

the camcorder case. But additionally if the DSC supports MP3 playback, and perhaps recording, the

ability of the ADCs to support full 48ks/s high quality stereo recording increases device flexibility.

The integrated video buffer allows direct connection to the TV for display of moving and still images.

WM8980GEFL/V Datasheet(PDF) 16 Page - Wolfson Microelectronics plc

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