WM8940GEFLSLASHV datasheet(65/85 Pages) WOLFSON

65 / 85 page

Pre-Production

WM8940

Pre-Production, Rev 3.0, February 2007

Table 59 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

10K=>0.3mA, less than 0.1mA for 100k/500k

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 59 AVDD Supply Current

POP MINIMISATION

Power-On-Bias Control (POB_CTRL) selects the bias current source for the output stages of the

WM8940. 0 selects the VMID derived bias source (normal operation), 1 selects a non-VMID derived

source which allows the output amplifiers to be enabled before VMID at start-up. This feature can be

used to minimise pops. Once VMID is enabled and has stabilised, POBCTRL should be set to 0.

charging of the VMID decoupling cap to follow a soft-start profile which minimises pops. This soft-

start profile has minimal impact on VMID charge time.

Fast VMID discharge is enabled using TOGGLE. Setting to 1 opens a low impedance discharge path

from VMID to GND. This function can be used during power down to reduce the discharge time of

the VMID decoupling cap. Must be set to 0 for normal operation.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

POB_CTRL

Power on Bias Control

0=normal (current bias based on VMID)

1=Startup (current bias not based on

VMID)

SOFT_START

VMID Soft Start

0=disabled

1=enabled

Additional

Control

TOGGLE

Fast VMID Discharge

0=normal

1=enable (used during power-down)

Table 60 POP Minimisation Control

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