AT85C51SND3Bx
Table 157. Audio Codec Output Gain
AORG4:0
AOLG4:0
AORG4:0
AOLG4:0
AORG4:0
AOLG4:0
Gain Value
6 dB
Gain Value
-8 dB
Gain Value
-22 dB
-24 dB
-26 dB
-28 dB
-30 dB
Mute
00000
00001
00010
00011
00100
00101
00110
00111
01000
01001
01010
01011
01100
01101
01110
4 dB
-10 dB
-12 dB
-14 dB
-16 dB
-18 dB
-20 dB
01111
2 dB
10000
0 dB
10001
-2 dB
-4 dB
-6 dB
10010
≥ 10011
Output Drive Control
Output buffers can operate in two modes depending on the power supply voltage. These
are low impedance or high impedance modes. The low impedance mode is only avail-
able in high power supply configuration and allows to drive a typical 32 Ω stereo
headphone, while the high impedance mode is available in low or high voltage power
supply configurations and allows to drive a typical 50 KΩ stereo amplifier. Control is
done by setting or clearing AODRV bit in ACCON according to Table 158.
Table 158. Audio Codec Output Drive Selection
AODRV
Drive Selection
0
1
Low/high voltage 50 KΩ drive
High voltage 32 Ω drive
Audio Inputs
The audio input system is based on a single sigma-delta A/D converter provided for
mono recording. It is enabled by setting the AIEN bit in ACCON.
Audio input system features are detailed in the following sections.
Inputs Sources
The audio input source can come from either an electret type microphone input or the
stereo lines inputs sources. The selection of the source is done by setting or clearing the
AISSEL bit in ACCON according to Table 159. When line inputs are selected as audio
input source, stereo channels are combined together in a mono signal prior to feed the
preamplifier.
Table 159. Audio Codec Input Source Selection
AISSEL
Selection
0
1
Line Inputs
Microphone Input
Audio Input Preamplifier Gain
The signals coming from audio inputs goes through a preamplifier to adapt levels prior
to feed the A/D converter.The preamplifier gain is controlled by AIPG2:0 bits in ACIPG
according to Table 160.
Table 160. Audio Codec Input Preamplifier Gain
AIPG2:0
Gain Value
AIPG2:0
Gain Value
AIPG2:0
Gain Value
000
0 dB
010
+12 dB
100
+24 dB
155
7632A–MP3–03/06
ATMEL [ ATMEL ]
