Datasheet

LM4549B

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SNAS598A –JULY 2012–REVISED MAY 2013

Mute MM5:MM0 Function

0 0 00000 0 dB attenuation

0 0 11111 46.5 dB attenuation

0 1 xxxxx As written

0 0 11111 As read back

1 X XXXXX *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 *0 dB attenuation

0 1111 45 dB 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 +12 dB gain to –34.5 dB attenuation in 1.5 dB steps. For stereo ports, volumes of the

left and right channels can be independently adjusted. Muting a given port is accomplished 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 20 dB boost for the selected microphone input by setting the 20dB bit (D6).

Mute Gx4:Gx0 Function

0 0 0000 +12 dB gain

0 0 1000 0 dB gain

0 1 1111 –34.5 dB 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

Product Folder Links: LM4549B