LM4546AVH NSC [National Semiconductor], LM4546AVH Datasheet - Page 9

• Manufacturer Part Number: LM4546AVH
• Description: AC 97 Rev 2 Multi-Channel Audio Codec with Sample Rate Conversion and National 3D Sound
• Manufacturer: NSC [National Semiconductor]

Connection Diagram
Pin Descriptions
PC_BEEP
CD_GND
PHONE
Name
CD_L
Pin
12
13
18
19
I / O
I
I
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.
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 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.
Left Stereo Channel Input
This line level input (1 Vrms nominal) is selectable at the left channel of the stereo Input Mux for
conversion by the left channel ADC. It can also be mixed into the left channel of the Stereo Mix 3D
signal at MIX1 under the control of the CD Volume register, 12h. The CD_L level can be muted
(along with CD_R) or adjusted from +12 dB to -34.5 dB in 1.5 dB steps. Stereo Mix 3D is mixed
into the Stereo Mix signal at MIX2 for access to the stereo outputs Line Out and Line Level Out.
AC Ground Reference
This input is the reference for the signals on both CD_L and CD_R. CD_GND is NOT a DC ground
and should be AC-coupled to the stereo source ground common to both CD_L and CD_R. The
three inputs CD_GND, CD_L and CD_R act together as a quasi-differential stereo input with
CD_GND providing AC common-mode feedback to reject ground noise. This can improve the input
SNR for a stereo source with a good common ground but precision resistors may be needed in
any external attenuators to achieve the necessary balance between the two channels.
200308 Version 5 Revision 1
See NS Package Number VBH48A
Order Number LM4546AVH
ANALOG I/O
Top View
Print Date/Time: 2009/07/15 15:26:52
9
20030802
www.national.com