WM8980CGEFLSLASHV datasheet(68/123 Pages) WOLFSON

68 / 123 page

WM8980

Pre-Production

PP, Rev 3.8, May 2012

ENABLING THE OUTPUTS

Each analogue output of the WM8980 can be separately enabled or disabled. The analogue mixer

associated with each output has a separate enable. All outputs are disabled by default. To save

power, unused parts of the WM8980 should remain disabled. The SLEEP bit should only be set on

to reduce residual device currents once all the other power management bits have been set to off.

Outputs can be enabled at any time, but it is not recommended to do so when BUFIO is disabled

(BUFIOEN=0) or when BUFDCOP is disabled (BUFDCOPEN=0) when configured in output boost

mode, as this may cause pop noise (see “Power Management” and “Applications Information”

sections).

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

Power

Management

BUFIOEN

Unused input/output tie off buffer enable

OUT3MIXEN

OUT3 mixer enable

OUT4MIXEN

OUT4 mixer enable

BUFDCOPEN

Output stage 1.5xAVDD/2 driver enable

Power

Management

ROUT1EN

ROUT1 output enable

LOUT1EN

LOUT1 output enable

SLEEP

0 = normal device operation

1 = residual current reduced in device

standby mode

Power

Management

LMIXEN

Left mixer enable

RMIXEN

Right mixer enable

VBUFEN

Video buffer enable

ROUT2EN

ROUT2 output enable

LOUT2EN

LOUT2 output enable

OUT3EN

OUT3 enable

OUT4EN

OUT4 enable

Table 50 Output Stages Power Management Control

Notes:

All “Enable” bits are 1 = ON, 0 = OFF

Disabling the outputs does not automatically mute the output mixers. To avoid pop noise, it is

recommended that the relevant mixer is muted before disabling outputs.

THERMAL SHUTDOWN

The speaker outputs can drive very large currents. To protect the WM8980 from overheating a

thermal shutdown circuit is included.

The thermal shutdown can be configured to produce an

interrupt when the device reaches approximately 125

oC. See General Purpose Input/Output section.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

R49

Output

control

TSDEN

Thermal Shutdown Enable

0 : thermal shutdown disabled

1 : thermal shutdown enabled

Table 51 Thermal Shutdown

UNUSED ANALOGUE INPUTS/OUTPUTS

Whenever an analogue input/output is disabled, it remains connected to a voltage source (either

AVDD/2 or 1.5xAVDD/2 as appropriate) through a resistor. This helps to prevent pop noise when the

output is re-enabled. The resistance between the voltage buffer and the output pins can be controlled

using the VROI control bit. The default impedance is low, so that any capacitors on the outputs can

charge up quickly at start-up. If a high impedance is desired for disabled outputs, VROI can then be

set to 1, increasing the resistance to about 30k

.

WM8980CGEFL/V Datasheet(PDF) 68 Page - Wolfson Microelectronics plc

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