WM8742GEDSSLASHV datasheet(41/66 Pages) CIRRUS

41 / 66 page

WM8742

Rev 4.4

OVERSAMPLING RATE CONTROL

The user has control of the oversampling ratio of the WM8742, and can set to the device to operate in

low, medium or high rate modes. For optimum operation of the digital filtering and other processing

on the WM8742 in PCM hardware mode, the user must ensure the correct value of OSR is set at all

times. Table 47 shows the correct settings:

NAME

DESCRIPTION

OSR/DSDR

Oversampling Rate Selection

0 = Low rate (32/44.1/48kHz)

Z = Medium rate (88.2/96kHz)

1 = High rate (176.4/192kHz)

Table 47 OSR/DSDR Hardware Control Pin Function

MUTE PIN

A soft mute can be applied to the WM8742 in the digital domain in all PCM. A logic low on the

MUTEB pin will cause the attenuation to ramp to infinite attenuation at a rate of 1022x(4/fs). Setting

MUTEB high will return the signal gain to its previous value.

Figure 26 shows the soft mute

characteristic.

In DSD Direct mode the MUTEB pin controls the analogue mute in the DAC. This analogue mute is a

‘hard’ mute and is applied and released as soon as the MUTEB pin is toggled.

NAME

DESCRIPTION

MUTEB/

SDOUT

Mute control

0 = Mute on (no output)

1 = Mute off (normal operation

Table 48 MUTEB Hardware Control Pin Function

0.02

0.04

0.06

0.08

0.1

0.12

0.14

Time (s)

Figure 26 Hardware Control Mode Soft Mute Characteristic

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