WM8753 Wolfson Microelectronics plc, WM8753 Datasheet - Page 48

• Manufacturer Part Number: WM8753
• Description: HI FI AND TELEPHONY DUAL CODEC
• Manufacturer: Wolfson Microelectronics plc

Advanced Information
INTERRUPT CONTROLLER
w
Figure 12 Speaker Output Connection
Figure 13 Recommended Circuit for Line Output
It is recommended to connect the DC coupled headphone outputs only to headphones, and not to the
line input of another device. Although the built-in short circuit protection will prevent any damage to
the headphone outputs, such a connection may be noisy, and may not function properly if the other
device is grounded.
SPEAKER OUTPUT
LOUT2 and ROUT2 can differentially drive a mono 8 speaker as shown below.
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.
Alternatively it is possible to drive 2 BTL stereo speakers, one between LOUT2 and OUT4, the other
between ROUT2 and OUT3, but only to about 250mW/2 due to the limited drive capability of the
OUT3/OUT4 outputs.
LINE OUTPUT
The analogue outputs, LOUT1/ROUT1 and LOUT2/ROUT2, can be used as line outputs. Additionally,
OUT3 and MONO2 can be used as a stereo line-out by setting OUT3SW=11 (reg. 24) and ensuring
the contents of registers 38 and 39 (mono-out mix) are the same as reg. 34 and 35 (left out mix).
Recommended external components are shown below.
The DC blocking capacitors and the load resistance together determine the lower cut-off frequency, f
Assuming a 10 k load and C1, C2 = 1 F:
f
Increasing the capacitance lowers f
diminish the bass response. The function of R1 and R2 is to protect the line outputs from damage
when used improperly.
The WM8753L can generate an interrupt based on seven separate level-sensitive sources. Each
source has programmable polarity and can be individually enabled. On detecting an enabled request
with the correct polarity, a status latch for that source is set. If any of the status latches are set, the
interrupt controller generates an internal INT signal that can be routed to one of the general purpose
pins. The value of the status latches can be obtained over the control interface using the read/write
mode. Each latch is cleared by disabling the source in question. Once cleared, the source can be re-
enabled if desired. Figure 14 illustrates the operation of the interrupt controller circuit.
c
= 1 / 2 (R
ROUT2INV = 1
WM8753L
WM8753L
L
+R
1
MIXER
MIXER
RIGHT
) C
LEFT
ROUT1/2
LOUT1/2
1
= 1 / (2 x 10.1k x 1 F) = 16 Hz
-1
ROUT2VOL
LOUT2VOL
1uF
1uF
C1
C2
c
, improving the bass response. Smaller values of C1 and C2 will
LOUT2
ROUT2
100 Ohm
100 Ohm
R1
R2
V
AGND
AGND
SPKR
= L-(-R) = L+R
LINE-OUT SOCKET
LINE-OUT SOCKET
(RIGHT)
(LEFT)
AI Rev 3.1 June 2004
WM8753L
48
c
.