at85c51snd3b ATMEL Corporation, at85c51snd3b Datasheet - Page 156

• Manufacturer Part Number: at85c51snd3b
• Description: Single-chip Digital Audio Decoder - Encoder With Usb 2.0 Interface
• Manufacturer: ATMEL Corporation

Line Inputs Preamplifier Gain
Microphone Bias
Audio DAC Interface
156
AT85C51SND3B
In AT85C51SND3B1 & AT85C51SND3B2, when Line Inputs are selected as output
source (e.g. FM decoder playback) two preamplifier gain values can be applied by set-
ting or clearing AILPG bit in ACIPG according to Table 161.
Table 161. Audio Codec Line Inputs Preamplifier Gain
In addition, voltage supply function for an electret type microphone is integrated deliver-
ing High bias (1.5V) or low bias (2v) voltage. The high bias voltage output is only
available in high power supply configuration, while the low bias voltage output is avail-
able in low or high voltage power supply configurations. Bias voltage output is selected
by AMBSEL bit in ACCON according to Table 163 and is enabled by AMBEN bit in
ACCON according to Table 162.
Table 162. Audio Codec Microphone Bias Control
Table 163. Audio Codec Microphone Bias Voltage Selection
The C51 core interfaces to the audio DAC interface through two special function regis-
ters: ADICON0 and ADICON1, the Audio DAC Interface Control registers (see
Table 183 and Table 184).
Figure 75 shows the audio interface block diagram where blocks are detailed in the fol-
lowing sections.
AIPG2:0
001
AMBSEL
AMBEN
AILPG
0
1
0
1
0
1
Gain Value
+6 dB
Gain Value
+6 dB
+12 dB
Control
Microphone bias output disabled
Microphone bias output enabled
Voltage Selection
high bias voltage 2V output
Low bias voltage 1.5 V output
AIPG2:0
011
Gain Value
+18 dB
AIPG2:0
≥ 101
Gain Value
Reserved
7632C–MP3–11/06