> i am going through the datasheet of AIC-23 Codec on TI board, in the
> datasheet i have come acrros this statement
> BOSR Base oversampling rate
> USB mode: 0 = 250 fs 1 = 272 fs
> Normal mode: 0 = 256 fs 1 = 384 fs
> where 0 and 1 are the bit to be set in the BOSR Register.
> My Query is, what actually mean by the 250 * fs and on what
> basis they get these values?
This is to do with the crystal used for the oscillator. Devices with USB
connectivity often have a 12MHz crytal source, so to save money on large
production runs the codec allows you to use a USB crystal oscillator source
to run the codec.
In USB mode, both PC and CD sampling rates can be derived.
12MHz / 250 = 48kHz (PC standard)
12MHz / 272 ~= 44.1kHz (CD standard)
In Normal mode, other oscillator sources are used such as 12.288MHz to
derive sample rates such as 48kHz using simple 2^n oversampling rates - see
section 3.3.2.2 of the AIC pdf document.
Cheers, Howard
Reply by ●June 2, 20062006-06-02
Hi All,
i am going through the datasheet of AIC-23 Codec on TI board, in the
datasheet i have come acrros this statement
BOSR Base oversampling rate
USB mode: 0 = 250 fs 1 = 272 fs
Normal mode: 0 = 256 fs 1 = 384 fs
where 0 and 1 are the bit to be set in the BOSR Register.
My Query is, what actually mean by the 250 * fs and on what
basis they get these values?
Note: the Data sheet is in the following link
"http://focus.ti.com/lit/ds/symlink/tlv320aic23b.pdf"
and page number 3-9
please help me out in solving this query,
Rgds
-Prasad