Rainbow Electronics AT73C246 - Manual (Page 55)

55
11050A–PMAAC–07-Apr-10
AT73C246
12. Audio Codec Functional Description
12.1 Description
AT73C246 features a high quality, low power stereo audio codec with integrated headphone
amplifier.
The playback channel accommodates 16 to 24-bit stereo programmable format entering the dig-
ital audio interface (I
2 S) and delivers an internal analog audio output through a 100dB SNR
Sigma Delta Stereo DAC. An output mixer allows to mix this DAC output with a line / aux or
microphone input.
A 16-32 Ohms Stereo headphone amplifier with virtual ground output provides a 97dB SNR out-
put for line / headphone loads. The virtual ground output allows to remove 2 space demanding
coupling capacitors on board.
On the record side, a multiplexer can select between a main stereo line input and a stereo auxil-
iary input such as an FM radio. A stereo microphone input with up to 46dB gain is provided. A
stereo input mixer allows mixing between line (or aux) and microphone channels before entering
a 96dB SNR Stereo Sigma Delta ADC. The digital audio signal is then digitally filtered and trans-
ferred to the I
2 S audio interface.
12.2 Audio Codec Block Diagram
Figure 12-1. Audio Codec Block Diagram
MUX
ADC DAC
DSP
+
Audio
Controller
BYPASS
0 -> -30dB
-77/+6dB
V MID
-34 -> +12dB
0 -> +46dB
LINL
AUXL
MICL
MICLN
MICBIAS AVDD
200K
VMID AGND
HPDET
Codec Bias
MCLK BCLK LRFS DAI PAO
I²S
HPVCM
HPL
MUX
ADC DAC
BYPASS
0 -> -30dB
-77/+6dB
-34 -> +12dB
LINR
AUXR
HPR
200K 2K
1dB Step
1dB Step
1dB Step
1dB Step
1dB Step
1dB Step
1dB Step
0 -> +46dB
MICR
MICRN
1dB Step