WM8980CGEFL/RV WOLFSON [Wolfson Microelectronics plc], WM8980CGEFL/RV Datasheet - Page 68

• Manufacturer Part Number: WM8980CGEFL/RV
• Description: Stereo CODEC with Speaker Driver and Video Buffer
• Manufacturer: WOLFSON [Wolfson Microelectronics plc]

WM8980
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ENABLING THE OUTPUTS
Table 50 Output Stages Power Management Control
THERMAL SHUTDOWN
Table 51 Thermal Shutdown
UNUSED ANALOGUE INPUTS/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).
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.
The speaker outputs can drive very large currents. To protect the WM8980 from overheating a
thermal shutdown circuit is included.
interrupt when the device reaches approximately 125
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.
R1
Power
Management
1
R2
Power
Management
2
R3
Power
Management
3
R49
Output
control
REGISTER
REGISTER
ADDRESS
ADDRESS
1
2
6
7
8
8
7
6
2
3
4
5
6
7
8
BIT
BIT
TSDEN
BUFIOEN
OUT3MIXEN
OUT4MIXEN
BUFDCOPEN
ROUT1EN
LOUT1EN
SLEEP
LMIXEN
RMIXEN
VBUFEN
ROUT2EN
LOUT2EN
OUT3EN
OUT4EN
LABEL
LABEL
1
The thermal shutdown can be configured to produce an
DEFAULT
0
0
0
0
0
0
0
0
0
0
0
0
0
0
DEFAULT
o
C. See General Purpose Input/Output section.
Thermal Shutdown Enable
0 : thermal shutdown disabled
1 : thermal shutdown enabled
Unused input/output tie off buffer enable
OUT3 mixer enable
OUT4 mixer enable
Output stage 1.5xAVDD/2 driver enable
ROUT1 output enable
LOUT1 output enable
0 = normal device operation
1 = residual current reduced in device
standby mode
Left mixer enable
Right mixer enable
Video buffer enable
ROUT2 output enable
LOUT2 output enable
OUT3 enable
OUT4 enable
DESCRIPTION
DESCRIPTION
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2
PP, Rev 3.8, May 2012
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Pre-Production
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