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LM4549A Datasheet(PDF) 22 Page - National Semiconductor (TI)

[Old version datasheet] Texas Instruments acquired National semiconductor.
Part No. LM4549A
Description  AC ’97 Rev 2.1 Codec with Sample Rate Conversion and National 3D Sound
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Maker  NSC [National Semiconductor (TI)]
Homepage  http://www.national.com
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LM4549A Datasheet(HTML) 22 Page - National Semiconductor (TI)

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Register Descriptions
Default settings are indicated by *.
RESET REGISTER (00h)
Writing any value to this register causes a Register Reset
which changes all registers back to their default values. If a
read is performed on this register, the LM4549A will return a
value of 0D40h. This value can be interpreted in accordance
with the AC ’97 Specification to indicate that National 3D
Sound is implemented and 18-bit data is supported for both
the ADCs and DACs.
MASTER VOLUME REGISTER (02h)
This output register allows the output level from either chan-
nel of the stereo LINE_OUT to be muted or attenuated over
the range 0 dB – 46.5 dB in nominal 1.5 dB steps. There are
5 bits of volume control for each channel and both stereo
channels can be individually attenuated. The mute bit (D15)
acts simultaneously on both stereo channels of LINE_OUT.
Mute
Mx4:Mx0
Function
0
0 0000
0dB attenuation
0
1 1111
46.5dB attenuation
1
X XXXX
*mute
Default: 8000h
LINE LEVEL VOLUME REGISTER (04h)
This output register allows the level from both channels of
LNLVL_OUT to be muted or individually attenuated over the
range 0 dB – 46.5 dB in nominal 1.5 dB steps. There are 5
bits of volume control for each channel plus one mute bit.
The mute bit (D15) acts on both channels. Operation of this
register and LNLVL_OUT matches that of the Master Volume
register and the LINE_OUT output.
MONO VOLUME REGISTER (06h)
This output register allows the level from MONO_OUT to be
muted or attenuated over the range 0 dB – 46.5 dB in
nominal 1.5 dB steps. There are 5 bits of volume control and
one mute bit (D15).
Mute
MM4:MM0
Function
0
0 0000
0dB attenuation
0
1 1111
46.5dB attenuation
1
X XXXX
*mute
Default: 8000h
PC BEEP VOLUME REGISTER (0Ah)
This input register adjusts the level of the mono PC_BEEP
input to the stereo mixer MIX2 where it is summed equally
into both channels of the Stereo Mix signal. PC_BEEP can
be both muted and attenuated over a range of 0 dB to 45 dB
in nominal 3 dB steps. Note that the default setting for the
PC_Beep Volume register is 0 dB attenuation rather than
mute.
Mute
PV3:PV0
Function
0
0000
*0dB attenuation
0
1111
45dB attenuation
1
XXXX
mute
Default: 0000h
MIXER INPUT VOLUME REGISTERS (Index 0Ch - 18h)
These input registers adjust the volume levels into the stereo
mixers MIX1 and MIX2. Each channel may be adjusted over
a range of +12dB gain to 34.5dB attenuation in 1.5dB steps.
For stereo ports, volumes of the left and right channels can
be independently adjusted. Muting a given port is accom-
plished by setting the MSB to 1. Setting the MSB to 1 for
stereo ports mutes both the left and right channels. The Mic
Volume register (0Eh) controls an additional 20dB boost for
the selected microphone input by setting the 20dB bit (D6).
Mute
Gx4:Gx0
Function
0
0 0000
+12dB gain
0
0 1000
0dB gain
0
1 1111
34.5dB attenuation
1
X XXXX
*mute
Default:
8008h (mono registers)
8808h (stereo registers)
RECORD SELECT REGISTER (1Ah)
This register independently controls the sources for the right
and left channels of the stereo ADC. The default value of
0000h corresponds to selecting the (mono) Mic input for both
channels.
SL2:SL0
Source for Left Channel ADC
0
*Mic input
1
CD input (L)
2
VIDEO input (L)
3
AUX input (L)
4
LINE_IN input (L)
5
Stereo Mix (L)
6
Mono Mix
7
PHONE input
SR2:SR0
Source for Right Channel ADC
0
*Mic input
1
CD input (R)
2
VIDEO input (R)
3
AUX input (R)
4
LINE_IN input (R)
5
Stereo Mix (R)
6
Mono Mix
7
PHONE input
Default: 0000h
RECORD GAIN REGISTER (1Ch)
This register controls the input levels for both channels of the
stereo ADC. The inputs come from the Record Select Mux
and are selected via the Record Select Control register, 1Ah.
The gain of each channel can be individually programmed
from 0dB to +22.5dB in 1.5dB steps. Both channels can also
be muted by setting the MSB to 1.
www.national.com
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