Datasheet

LM4549B

SNAS598A –JULY 2012–REVISED MAY 2013

www.ti.com

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 +22.5 dB in 1.5 dB steps. Both channels can also be muted by setting the

MSB to 1.

Table 10. Record Gain Register (1Ch)

Mute Gx3:Gx0 Function

0 1111 22.5 dB gain

0 0000 0 dB gain

1 XXXX *mute

Default: 8000h

General Purpose Register (20h)

This register controls many miscellaneous functions implemented on the LM4549B. The miscellaneous control

bits include POP which allows the DAC output to bypass the TI 3D Sound circuitry, 3D which enables or disables

the TI 3D Sound circuitry, MIX which selects the MONO_OUT source, MS which controls the Microphone

Selection mux and LPBK which connects the output of the stereo ADC to the input of the stereo DAC. LPBK

provides a mixed-mode analog and digital loopback path between analog inputs and analog outputs. This is an

18 bit digital loopback at 48 kHz, bypassing the SRC logic, even if a sample rate other than 48 kHz is selected.

BIT Function

PCM Out Path: *0 = 3D allowed

POP

1 = 3D bypassed

TI 3D Sound: *0 = off

1 = on

Mono output select: *0 = Mix

MIX

1 = Mic

Mic select: *0 = MIC1

1 = MIC2

ADC/DAC Loopback: *0 = No Loopback

LPBK

1 = Loopback

Default: 0000h

Product Folder Links: LM4549B