WM8940
Pre-Production
GPIOPOL
CSB/GPIO
SPKNEN/
SPKPEN
MONOEN
SPEAKER
ENABLED
MONO
OUTPUT
ENABLED
0
0
0
1
1
0
0
1
1
0
1
X
X
X
X
0
1
X
X
0
1
0
1
X
X
No
No
0
0
0
1
1
1
1
Yes
No
No
No
No
Yes
No
No
No
Yes
No
No
Yes
No
Table 41 Output Switch Operation (GPIOSEL=001)
THERMAL SHUTDOWN
The speaker outputs can drive very large currents. To protect the WM8940 from overheating a
thermal shutdown circuit is included. The thermal shutdown can be configured to produce an
interrupt when the device reaches approximately 125oC. See General Purpose Input/Output section.
REGISTER
ADDRESS
BIT
LABEL
TSDEN
DEFAULT
DESCRIPTION
R49
Output control
1
1
Thermal Shutdown Enable
0 : thermal shutdown disabled
1 : thermal shutdown enabled
Table 42 Thermal Shutdown
SPEAKER OUTPUT
SPKOUTP/N can differentially drive a mono 8Ω Bridge Tied Load (BTL) speaker as shown below.
Figure 22 Speaker Output Connection
Pre-Production, Rev 3.0, February 2007
48
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WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
