LM4540 National Semiconductor, LM4540 Datasheet - Page 7

• Manufacturer Part Number: LM4540
• Description: AC 97 Codec with National 3D Sound
• Manufacturer: National Semiconductor

PC_BEEP
Connection Diagram
Pin Description
Analog I/O
CD_GND
PHONE
Name
CD_L
Pin
12
13
18
19
I / O
I
I
I
I
Functional Description
This is a mono input which gets summed into the stereo line output after the National 3D
Sound block. The PC_BEEP level can be adjusted from 0dB to −45dB in 3dB steps, or
muted, via register 0Ah.
This is a mono input which gets summed into the stereo line output after the National 3D
Sound block. The PHONE level can be adjusted from +12dB to −34.5dB in 1.5dB steps as
well as muted via register 0Ch.
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 or CD_R inputs.
CD_GND is an AC ground point not a DC ground point. This input must be AC-coupled to
the CD input signal’s ground.
See NS Package Number VBH48A
Order Number LM4540VH
Top View
7
DS100906-2
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