WM8941 datasheet(74/96 Pages) WOLFSON

74 / 96 page

WM8941

Pre Production

PP, Rev 3.3, December 2007

POWER MANAGEMENT

VMID

The analogue circuitry will not work when VMID is disabled (VMIDSEL[1:0] = 00b). The impedance

of the VMID resistor string, together with the decoupling capacitor on the VMID pin will determine the

start-up time of the VMID circuit.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

Power

management 1

1:0

VMIDSEL 00

Reference string impedance to VMID pin

(determines startup time):

00=off (open circuit)

01=50kΩ

10=250kΩ

11=5kΩ (for fastest startup)

Table 58 VMID Impedance Control

BIASEN

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

Power

management 1

BIASEN

Analogue amplifier bias control

0=Disabled

1=Enabled

Table 59 BIASEN Control

ESTIMATED SUPPLY CURRENTS

When either the DAC or ADC are enabled it is estimated that approximately 4mA will be drawn from

DVDD when fs=48kHz (This will be lower at lower sample rates). When the PLL is enabled an

additional 700 microamps will be drawn from DVDD.

Table 60 shows the estimated 3.3V AVDD current drawn by various circuits, by register bit.

AVDD CURRENT (MILLIAMPS)

MONOEN

0.2mA

PLLEN

1.4mA (with clocks applied)

MICBEN

0.5mA

BIASEN

0.3mA

BUFIOEN

0.1mA

VMIDSEL

5K=>0.3mA, less than 0.1mA for 50k/250k

BOOSTEN

0.2mA

INPPGAEN

0.2mA

ADCEN

2.6mA

MONOEN

0.2mA

SPKPEN

1mA from SPKVDD

SPKNEN

1mA from SPKVDD

MONOMIXEN

0.2mA

SPKMIXEN

0.2mA

DACEN

1.8mA

Table 60 AVDD Supply Current

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