WM8971L Wolfson Microelectronics Ltd., WM8971L Datasheet - Page 37

• Manufacturer Part Number: WM8971L
• Description: Stereo Codec for Portable Audio Applications
• Manufacturer: Wolfson Microelectronics Ltd.

Production Data
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THERMAL SHUTDOWN
HEADPHONE OUTPUT
The speaker and headphone outputs can drive very large currents. To protect the WM8971L from
overheating a thermal shutdown circuit is included. If the device temperature reaches approximately
150
(OUT1L/R, OUT2L/R) will be disabled.
Table 29 Thermal Shutdown
Analogue outputs LOUT1/ROUT1 and LOUT2/ROUT2, can drive a 16Ω or 32Ω headphone load,
through DC blocking capacitors.
Figure 14 Recommended Headphone Output Configuration
The DC blocking capacitors and the load resistance together determine the lower cut-off frequency,
f
will diminish the bass response. Assuming a 16 Ohm load and C1, C2 = 220µF:
f
SPEAKER OUTPUT
LOUT2 and ROUT2 can differentially drive a mono 8Ω speaker as shown below.
Figure 15 Speaker Output Connection
The right channel is inverted by setting the ROUT2INV bit, so that the signal across the loudspeaker
is the sum of left and right channels.
LINE OUTPUT
The analogue outputs, LOUT1/ROUT1 and LOUT2/ROUT2, can be used as line outputs.
Recommended external components are shown below.
Figure 16 Recommended Circuit for Line Output
c
c
. Increasing the capacitance lowers f
R23 (17h)
Additional
Control (1)
= 1 / 2π R
REGISTER
0
ADDRESS
C and the thermal shutdown circuit is enabled (TSDEN = 1) then the analogue outputs
L
C
1
= 1 / (2π x 16Ω x 220µF) = 45 Hz
8
BIT
TSDEN
LABEL
c
, improving the bass response. Smaller capacitance values
0
DEFAULT
Thermal Shutdown Enable
0 : thermal shutdown disabled
1 : thermal shutdown enabled
DESCRIPTION
PD Rev 4.1 August 2005
WM8971L
37