lm4549a National Semiconductor Corporation, lm4549a Datasheet - Page 9

• Manufacturer Part Number: lm4549a
• Description: Ac ?97 Rev 2.1 Multi-channel Audio Codec With Sample Rate Conversion And National 3d Sound
• Manufacturer: National Semiconductor Corporation

Connection Diagram
Pin Descriptions
PC_BEEP
PHONE
Name
Pin
12
13
I / O
I
I
Functional Description
Mono Input
This line level (1 Vrms nominal) mono input is mixed equally into both channels of the Stereo
Mix signal at MIX2 under the control of the PC_Beep Volume control register, 0Ah. The
PC_BEEP level can be muted or adjusted from 0 dB to -45 dB in 3 dB steps. The Stereo Mix
signal feeds both the Line Out and Line Level Out analog outputs and is also selectable at
the Record Select Mux. During Initialization or Cold Reset, (reset pin held active low),
PC_BEEP is switched directly to both channels of the Line Out stereo output, bypassing all
volume controls. This allows signals such as PC power-on self-test tones to be heard through
the PC’s audio system before the codec registers are configured.
Mono Input
This line level (1 Vrms nominal) mono input is selectable at the Record Select Mux for
conversion by either channel of the stereo ADC. It can also be mixed equally into both
channels of the Stereo Mix signal at MIX2 under the control of the Phone Volume register,
0Ch. The PHONE level can be muted or adjusted from +12 dB to -34.5 dB in 1.5 dB steps.
The Stereo Mix signal feeds both the Line Out and Line Level Out analog stereo outputs and
is also selectable at the Record Select Mux.
See NS Package Number VBH48A
Order Number LM4549AVH
ANALOG I/O
Top View
9
20029902
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