WM8951L datasheet(33/42 Pages) WOLFSON

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Production Data

WM8951

PD Rev 4.1 December 2007

OSCPD: Powers off the on board crystal oscillator. The MCLK input will function independently of the

Oscillator being powered down.

CLKOUTPD: Powers down the CLOCKOUT pin. This conserves power, reduces digital noise and RF

emissions if not required. CLKOUT is tied low when powered down.

The device can be put into a standby mode (STANDBY) by powering down all the audio circuitry

under software control as shown in Table 21. If the crystal oscillator and/or CLOKOUT pins are being

used to derive the system master clock, these should probably never be powered off in standby.

Provision has been made to independently power off these areas according to Table 21.

DESCRIPTION

STANDBY, but with Crystal Oscillator OS

and CLKOUT available

STANDBY, but with Crystal Oscillator OS

available, CLKOUT not-available

STANDBY, Crystal oscillator and CLKOUT

not-available.

Table 21 Standby Mode

In STANDBY mode the Control Interface, a small portion of the digital and areas of the analogue

circuitry remain active. The active analogue includes the analogue VMID reference so that the

analogue line inputs remain biased to VMID. This reduces any audible effects caused by DC glitches

when entering or leaving STANDBY mode.

The device can be powered off by writing to the POWEROFF bit of the Power Down register. In

POWEROFF mode the Control Interface and a small portion of the digital remain active. The

analogue VMID reference is disabled. As in STANDBY mode the crystal oscillator and/or CLKOUT

pin can be independently controlled. Refer to Table 22.

DESCRIPTION

POWEROFF, but with Crystal Oscillator OS and

CLKOUT available

POWEROFF, but with Crystal Oscillator OS

available, CLKOUT not-available

POWEROFF, Crystal oscillator and CLKOUT

not-available.

Table 22 Poweroff Mode

Note:

For minimum power consumption unused control bits 3 and 4 should be set to ‘1’.

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