ASAHI KASEI [AK2301A]
<MS0300-E-01> 13 2005/8
FUNCTIONAL DESCRIPTIONS
PCM CODEC
- A/D
Analog input signal is converted to 14bit PCM data. The analog signal is fed to the anti-aliasing filter
(AAF) before the converting PCM data, to prevent signals around the sampling rate from folding back
into the voice band. The converted PCM data passes through the band limiting filter which Frequency
response is designated in page8, and output from the DX pin with MSB first format. It is synchronized
with rising edge of the BCLK. This PCM data is 2’s compliment 2digit data and full scale is defined as
3.14dBm0. The analog input of 0.762Vrms is converted to a digital code of 3.14dBm0.
- D/A
Input PCM data from the DR pin is through the digital filter which Frequency response is designated in page8,
and converted analog signal. This analog signal is removed the high frequency element with SMF (fc=30kHz
typ) and output from the VR pin. The input PCM data is 2’s compliment 2digit data and full scale is defined as
3.14dBm0. When the input signal is 3.14dBm0, the level of the analog output signal becomes 0.762Vrms.
- PCM digital code
The relation ship between the analog signal and the 14bit linear code.
Signal level 14bit linear CODE (MSB First)
+Full code 01 1111 1111 1111
Peak value of the PCM 0dBm0 CODEC 01 0110 0100 1010
PCM 0-CODE 00 0000 0000 0000
-Full scale 10 0000 0000 0000
