WM8776 datasheet(16/57 Pages) WOLFSON

16 / 57 page

WM8776

Production Data

PD Rev 4.0 April 2005

DEVICE DESCRIPTION

INTRODUCTION

WM8776 is a complete 2-channel DAC, 2-channel ADC audio CODEC, with flexible input multiplexor

including digital interpolation and decimation filters, multi-bit sigma delta stereo ADC, and switched

capacitor multi-bit sigma delta DACs with analogue volume controls on each channel and output

smoothing filters. It is available in a single package and controlled by either a 3-wire or 2-wire

software interface. The 3-wire interface is compatible with the SPI standard.

An analogue bypass path option is available, to allow stereo analogue signals from any of the 5

stereo inputs to be sent to the stereo outputs via the main volume controls. This allows a purely

analogue input to analogue output high quality signal path to be implemented if required.

The DAC and ADC have separate left/right clocks, bit clocks, master clocks and data I/Os. The

Audio Interface may be configured to operate in either master or slave mode. In Slave mode

ADCLRC, DACLRC, ADCBCLK and DACBCLK are all inputs. In Master mode ADCLRC, DACLRC,

ADCBCLK and DACBCLK are outputs.

The input multiplexor to the ADC is configured to allow large signal levels to be input to the ADC,

using external resistors to reduce the amplitude of larger signals to within the normal operating range

of the ADC. The ADC has an analogue input PGA and a digital gain control, accessed by one

-21dB in 0.5dB steps. The digital gain control allows attenuation from -21.5dB to -103dB in 0.5dB

steps. This allows the user maximum flexibility in the use of the ADC.

The DAC has its own digital volume control, which is adjustable between 0dB and -127.5dB in 0.5dB

steps. There is also an analogue volume control on the headphone outputs, which is adjustable

between +6dB and -73dB in 1dB steps. The analogue and digital volume controls may be operated

independently. In addition a zero cross detect circuit is provided for both analogue and digital volume

controls. When analogue volume zero-cross detection is enabled the attenuation values are only

updated when the input signal to the gain stage is close to the analogue ground level. The digital

volume control detects a transition through the zero point before updating the volume. This

minimises audible clicks and ‘zipper’ noise as the gain values change.

The DAC output incorporates an input selector and mixer allowing a signal to be either switched into

the signal path in place of the DAC signal or mixed with the DAC signal before the volume control.

Use of external resistors allows larger input levels to be accepted by the device, giving maximum

user flexibility.

Internal functionality is controlled by CE, CL, DI and MODE input pins. The MODE pin determines

which of the two control interface modes is selected.

Operation using system clock of 128fs, 192fs, 256fs, 384fs, 512fs or 768fs is provided. In Slave

mode selection between clock rates is automatically controlled. In master mode the master clock to

sample rate ratio is set by control bits ADCRATE and DACRATE. ADC and DAC may run at different

rates and have their own bit clocks and master clocks.

The audio data interface supports right, left and I

2S interface formats along with a highly flexible DSP

serial port interface.

WM8776 Datasheet(PDF) 16 Page - Wolfson Microelectronics plc

WM8776 Datasheet(HTML) 16 Page - Wolfson Microelectronics plc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57

Datasheet Download

Link URL