ANALOG I/O (Continued)

Name

Pin

I / O

Functional Description

LINE_OUT_L

35

O

Left Stereo Channel Output

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.

LINE_OUT_R

36

O

Right Stereo Channel Output

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_OUT

37

O

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. The optional National 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.

DIGITAL I/O AND CLOCKING

Name

Pin

I / O

Functional Description

XTL_IN

2

I

24.576 MHz crystal or oscillator input

To complete the oscillator circuit use a fundamental mode crystal operating in parallel

resonance and connect a 1M

Ω resistor across pins 2 and 3. Choose the load capacitors

(Figure 2, C1, C2) to suit the load capacitance required by the crystal (e.g. C1=C2=33pF

for a 20 pF crystal Assumes that each ’Input + trace’ 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

This pin is only used when the codec is in Primary mode. It may be left open (NC) for any

Secondary mode.

XTL_OUT

3

O

24.576 MHz crystal output

Used with XTAL_IN to configure a crystal oscillator.

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).

SDATA_OUT

5

I

Input to codec

This is the input for AC Link Output Frames from an AC ’97 Digital Audio Controller to the

LM4546B codec. These frames can contain both control data and DAC PCM audio data. This

input is sampled by the LM4546B on the falling edge of BIT_CLK.

BIT_CLK

6

I/O

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 (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.

SDATA_IN

8

O

Output from codec

This is the output for AC Link Input Frames from the LM4546B codec to an AC ’97 Digital

Audio Controller. These frames can contain both codec status data and PCM audio data from

the ADCs. The LM4546B clocks data from this output on the rising edge of BIT_CLK.

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