wm8982gefl-v Wolfson Microelectronics plc, wm8982gefl-v Datasheet - Page 57

• Manufacturer Part Number: wm8982gefl-v
• Description: Mono Codec With Speaker Driver And Video Buffer
• Manufacturer: Wolfson Microelectronics plc

Pre-Production
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THERMAL SHUTDOWN
Table 47 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 30kΩ.
Table 48 Disabled Outputs to VREF Resistance
A dedicated buffer is available for tying off unused analogue I/O pins as shown in Figure 32. This
buffer can be enabled using the BUFIOEN register bit.
If the SPKRBOOST or MONOBOOST bits are set then the relevant outputs will be tied to the output
of the DC level shift buffer at 1.5xAVDD/2 when disabled.
Figure 32 summarises the tie-off options for the speaker and mono output pins.
The speaker outputs can drive very large currents. To protect the WM8982 from overheating a
thermal shutdown circuit is included. If the device temperature reaches approximately 125
thermal shutdown circuit is enabled (TSDEN=1) then the speaker amplifiers will be disabled if
TSDEN is set. The thermal shutdown may also be configured to generate an interrupt. See the GPIO
and Interrupt Controller section for details.
R49
Output
control
R49
REGISTER
ADDRESS
REGISTER
ADDRESS
1
BIT
0
BIT
TSDEN
VROI
LABEL
LABEL
1
DEFAULT
0
DEFAULT
Thermal Shutdown Enable
0 : thermal shutdown disabled
1 : thermal shutdown enabled
VREF (AVDD/2 or 1.5xAVDD/2) to
analogue output resistance
0: approx 1kΩ
1: approx 30 kΩ
DESCRIPTION
PP, Rev 3.2, September 2008
DESCRIPTION
WM8982
0
C and the
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