Datasheet

LM4549B
SNAS598A –JULY 2012–REVISED MAY 2013 www.ti.com
ANALOG I/O (continued)
Name Pin I / O Functional Description
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 the Stereo Mix 3D
LINE_IN_R 24 I 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
This line level output (1 Vrms nominal) is fed from the left channel of the Stereo Mix signal from MIX2
LINE_OUT_L 35 O
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
This line level output (1 Vrms nominal) is fed from the right channel of the Stereo Mix signal from MIX2
LINE_OUT_R 36 O
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 channels from MIX1.
MONO_OUT 37 O The optional TI 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
This line level output (1 Vrms nominal) is fed from the left channel of the Stereo Mix signal from MIX2
LNLVL_OUT_L 39 O
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
This line level output (1 Vrms nominal) is fed from the right channel of the Stereo Mix signal from MIX2
LNLVL_OUT_R 41 O
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
Name Pin 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 1MΩ resistor across pins 2 and 3. Choose the load capacitors (Figure 9, C1, C2) to suit the
crystal (e.g. C1 = C2 = 33 pF for a crystal designed for a 20 pF load. Assumes that each 'Input + trace'
XTL_IN 2 I capacitance = 7 pF)
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.
XTL_OUT 3 O
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
This is the input for AC Link Output Frames from an AC '97 Digital Audio Controller to the LM4549B
SDATA_OUT 5 I
codec. These frames can contain both control data and DAC PCM audio data. This input is sampled
by the LM4549B on the falling edge of BIT_CLK.
AC Link clock
An OUTPUT when in Primary Codec mode. This pin provides a 12.288 MHz clock for the AC Link.
The clock is derived (internally divided by two) from the 24.576 MHz signal at the crystal input
BIT_CLK 6 I/O
(XTL_IN).
This pin is an INPUT when the codec is configured in any of the Secondary Codec modes and would
normally use the AC Link clock generated by a Primary Codec.
Output from codec
This is the output for AC Link Input Frames from the LM4549B codec to an AC '97 Digital Audio
SDATA_IN 8 O
Controller. These frames can contain both codec status data and PCM audio data from the ADCs. The
LM4549B clocks data from this output on the rising edge of BIT_CLK.
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