LM4548A Datasheet, PDF (11/34 Pages) National Semiconductor (TI) – AC ’97 Rev 2 Multi-Channel Audio Codec with Sample Rate Conversion and National 3D Sound

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Name
Pin
LINE_IN_L
23
LINE_IN_R
24
LINE_OUT_L
35
LINE_OUT_R
36
MONO_OUT
37
LNLVL_OUT_L
39
LNLVL_OUT_R
41
Name
Pin
XTL_IN
2
XTL_OUT
3
SDATA_OUT
5
OBSOLETE
LM4548A
SNOS988D – NOVEMBER 2002 – REVISED APRIL 2013
ANALOG I/O (continued)
I/O
Functional Description
Left Stereo Channel Input
This line level input (1 Vrms nominal) is selectable at the left channel of the stereo Record
Select Mux for conversion by the left channel ADC. It can also be mixed into the left
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channel of the Stereo Mix 3D signal at MIX1 under the control of the Line In Volume
register, 10h. The LINE_IN_L level can be muted (along with LINE_IN_R) or adjusted from
+12 dB to -34.5 dB in 1.5 dB steps. Stereo Mix 3D is combined into the Stereo Mix signal at
MIX2 for access to the stereo outputs Line Out and Line Level Out.
Right Stereo Channel Input
This line level input (1 Vrms nominal) is selectable at the right channel of the stereo Input
Mux for conversion by the right channel ADC. It can also be mixed into the right channel of
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the Stereo Mix 3D signal at MIX1 under the control of the Line In Volume register, 10h. The
LINE_IN_R level can be muted (along with LINE_IN_L) or adjusted from +12 dB to -34.5 dB
in 1.5 dB steps. Stereo Mix 3D is combined into the Stereo Mix signal at MIX2 for access to
the stereo outputs Line Out and Line Level Out.
Left Stereo Channel Output
O
This line level output (1 Vrms nominal) is fed from the left channel of the Stereo Mix signal
from MIX2 via the Master Volume register, 02h. The LINE_OUT_L amplitude can be muted
(along with LINE_OUT_R) or adjusted from 0 dB to -46.5 dB in 1.5 dB steps.
Right Stereo Channel Output
O
This line level output (1 Vrms nominal) is fed from the right channel of the Stereo Mix signal
from MIX2 via the Master Volume register, 02h. The LINE_OUT_R amplitude can be muted
(along with LINE_OUT_L) or adjusted from 0 dB to -46.5 dB in 1.5 dB steps.
Mono Output
This mono line level output (1 Vrms nominal) is fed from either a microphone input (MIC1 or
MIC2, after boost amplifier) or from the mono sum of the left and right Stereo Mix 3D
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channels from MIX1. The optional Texas Instruments 3D Sound enhancement can be
disabled (default) by the 3D bit (bit D13) in the General Purpose register, 20h. Choice of
input is by the MIX bit (D9) in the same register. MIX=0 selects a microphone input. Output
level can be muted or adjusted from 0 dB to -46.5 dB in 1.5 dB steps via the Mono Volume
register, 06h.
Left Stereo Channel Output
O
This line level output (1 Vrms nominal) is fed from the left channel of the Stereo Mix signal
from MIX2 via the Line Level Volume register, 04h. The LNLVL_OUT_L amplitude can be
muted (along with LNLVL_OUT_R) or adjusted from 0 dB to - 46.5 dB in 1.5 dB steps
Right Stereo Channel Output
O
This line level output (1 Vrms nominal) is fed from the right channel of the Stereo Mix signal
from MIX2 via the Line Level Volume register, 04h. The LNLVL_OUT_R amplitude can be
muted (along with LNLVL_OUT_L) or adjusted from 0 dB to - 46.5 dB in 1.5 dB steps
DIGITAL I/O AND CLOCKING
I/O
Functional Description
24.576 MHz crystal or oscillator input
To complete the oscillator circuit use a fundamental mode crystal operating in parallel
resonance and connect a 1 MΩ resistor across pins 2 and 3. Choose the load capacitors
(Figure 9, C1, C2) to suit the load capacitance required by the crystal (e.g. C1 = C2 = 33
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pF for a 20 pF crystal).
This pin may also be used as the input for an external oscillator (24.576 MHz nominal) at
standard logic levels (V_IH, V_IL).
This pin is only used when the codec is in Primary mode. It may be left open (NC) for any
Secondary mode.
24.576 MHz crystal output
Used with XTAL_IN to configure a crystal oscillator.
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When the codec is used with an external oscillator this pin should be left open (NC).
When the codec is configured in a Secondary mode this pin is not used and may be left
open (NC).
Input to codec
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This is the input for AC Link Output Frames from an AC '97 Digital Audio Controller to the
LM4548A codec. These frames can contain both control data and DAC PCM audio data.
This input is sampled by the LM4548A on the falling edge of BIT_CLK.
Copyright © 2002–2013, Texas Instruments Incorporated
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