WM8753L
Advanced Information
OUT4 OUTPUT
The OUT4 output can be used to output a buffered Vmid for driving a mono or stereo headset in
capless mode, output the signal from the record mixer or drive out an inverted LOUT2 signal. The
output mode is determined by OUT4SW[1:0]. This output is enabled by setting register bit OUT4 high.
REGISTER
ADDRESS
BIT
8:7
LABEL
DEFAULT
00
DESCRIPTION
OUT4 Output select
00 = VREF
01 = Record Mixer
10 = LOUT2 signal
R63 (3Fh)
Additional
Control
OUT4SW
[1:0]
(volume controlled by LOUT2VOL)
11 = unused
Table 40 OUT4SW control of OUT4
ZERO CROSS TIMEOUT
A zero-cross timeout function is also provided so that if zero cross is enabled on the input or output
pgas the gain will automatically update after a timeout period if a zero cross has not occurred. This is
enabled by setting TOEN. The timeout period is dependent on the clock input to the digital and is
equal to 221 * input clock period. The timeout clock may be set to be derived from either the mclk or
pcmclk using SLWCLK..
REGISTER
ADDRESS
BIT
LABEL
TOEN
DEFAULT
DESCRIPTION
R18 (12h)
Additional
Control
0
0
0
0
Timeout clock enable
0 = timeout clock disabled
1 = timeout clock enabled
R52 (34h)
SLWCLK
Timeout and Headphone switch clock
source
Clock Control
0 = mclk
1 = pcm clk
Table 41 Timeout Clock Controls
ENABLING THE OUTPUTS
Each analogue output of the WM8753L can be separately enabled or disabled. The analogue mixer
associated with each output is powered on or off along with the output pin. All outputs are disabled by
default. To save power, unused outputs should remain disabled.
Outputs can be enabled at any time, except when VREF is disabled (VR=0), as this may cause pop
noise (see “Power Management” and “Applications Information” sections)
REGISTER
ADDRESS
BIT
LABEL
DEFAULT
DESCRIPTION
R22 (16h)
Power
Management
(3)
8
7
6
5
4
3
2
1
LOUT1
0
0
0
0
0
0
0
0
LOUT1 Enable
ROUT1
LOUT2
ROUT2
OUT3
ROUT1 Enable
LOUT2 Enable
ROUT2 Enable
OUT3 Enable
OUT4 Enable
MONO1 Enable
MONO2 Enable
OUT4
MONO1
MONO2
Note: All “Enable” bits are 1 = ON, 0 = OFF
Table 42 Analogue Output Control
AI Rev 3.1 June 2004
45
w
WOLFSON [ WOLFSON MICROELECTRONICS PLC ]
