Datasheet

OBSOLETE
LM4550
www.ti.com SNAS032F –SEPTEMBER 2001–REVISED APRIL 2013
Mute PV3:PV0 Function
0 0000 *0dB attenuation
0 1111 45dB 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 +12dB gain to 34.5dB attenuation in 1.5dB 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 20dB boost for the selected microphone input by setting the 20dB bit (bit D6).
Mute Gx4:Gx0 Function
0 0 0000 +12dB gain
0 0 1000 0dB gain
0 1 1111 34.5dB 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
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 +22.5dB in 1.5dB steps. Both channels can also be muted by setting the
MSB to 1.
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