lm4550 National Semiconductor Corporation, lm4550 Datasheet - Page 10

• Manufacturer Part Number: lm4550
• Description: Ac ?97 Rev 2.1 Multi-channel Audio Codec With Stereo Headphone Amplifier, Sample Rate Conversion And National 3d Sound
• Manufacturer: National Semiconductor Corporation

www.national.com
LINE_OUT_R
LINE_OUT_L
Pin Descriptions
MONO_OUT
HP_OUT_C
HP_OUT_R
HP_OUT_L
LINE_IN_R
LINE_IN_L
VIDEO_R
CD_GND
Name
CD_R
CD_L
MIC1
MIC2
Pin
17
18
19
20
21
22
23
24
35
36
37
39
40
41
I / O
O
O
O
O
O
I
I
I
I
I
I
I
I
I
(Continued)
Functional Description
This line level input can be routed through the Input Mux and recorded by the right ADC. In
addition, this analog input gets summed into the right output stream. The amount of VIDEO_R
signal mixed in the right output stream can be adjusted from +12dB to −34.5dB in 1.5dB
steps as well as muted via register 14h.
This line level input can be routed through the Input Mux and recorded by the left ADC. In
addition, this analog input gets summed into the left output stream. The amount of CD_L
signal mixed in the left output stream can be adjusted from +12dB to −34.5dB in 1.5dB steps
as well as muted via register 12h.
This input can be used to reject common mode signals on the CD_L and CD_R inputs.
CD_GND is an AC ground point and not a DC ground point. This input must be AC-coupled
to the source signal’s ground.
This line level input can be routed through the Input Mux and recorded by the right ADC. In
addition, this analog input gets summed into the right output stream. The amount of CD_R
signal mixed in the right output stream can be adjusted from +12dB to −34.5dB in 1.5dB
steps as well as muted via register 12h.
Either MIC1 or MIC2 can be selected via software and routed through the Input Mux for
recording. The 20dB boost circuit is enabled/disabled via register 0Eh. Also, the amount of
mic signal mixed in the output stream can be adjusted from +12dB to −34.5dB in 1.5dB steps
as well as muted via register 0Eh.
Either MIC1 or MIC2 can be selected via software and routed through the Input Mux for
recording. The 20dB boost circuit is enabled/disabled via register 0Eh. Also, the amount of
mic signal mixed in the output stream can be adjusted from +12dB to −34.5dB in 1.5dB steps
as well as muted via register 0Eh.
This line level input can be routed through the Input Mux and recorded by the left ADC. In
addition, this analog input gets summed into the left output stream. The amount of LINE_IN_L
signal mixed in the left output stream can be adjusted from +12dB to −34.5dB in 1.5dB steps
as well as muted via register 10h.
This line level input can be routed through the Input Mux and recorded by the right ADC. In
addition, this analog input gets summed into the right output stream. The amount of
LINE_IN_R signal mixed in the right output stream can be adjusted from +12dB to −34.5dB in
1.5dB steps as well as muted via register 10h.
This is a post-mixed output for the left audio channel. The level of this output can be adjusted
from 0dB to −45dB in 1.5dB steps as well as muted via register 02h.
This is a post-mixed output for the right audio channel. The level of this output can be
adjusted from 0dB to −45dB in 1.5dB steps as well as muted via register 02h.
This line level output is either the post-mixed output or the mic input. The level of this output
can be adjusted from 0dB to −45dB in 1.5dB steps as well as muted via register 06h.
This is a post-mixed output for the left audio channel. The level of this output can be adjusted
from 0dB to −45dB in 1.5dB steps as well as muted via register 04h. HP_OUT_L has a
nominal gain of 3dB with respect to the left output mixer level and is designed for driving a
32Ω impedance with minimal distortion.
This input can be used to reject common mode signals on the headphone outputs.
HP_OUT_C is an AC ground point not DC ground point. Thus, this input must be capacitively
coupled (not directly coupled) to analog ground.
This is a post-mixed output for the left audio channel. The level of this output can be adjusted
from 0dB to −45dB in 1.5dB steps as well as muted via register 04h. HP_OUT_L has a
nominal gain of 3dB with respect to the left output mixer level and is designed for driving a
32Ω impedance with minimal distortion.
ANALOG I/O (Continued)
10