XO-1.5 audio input DC mode

Richard A. Smith richard at laptop.org
Wed Nov 24 09:41:36 EST 2010

On 11/24/2010 06:52 AM, Sascha Silbe wrote:

> 2. The voltage I see with bias off is probably generated internally by
>     the codec chip. I don't think the chip designers envisioned it to be
>     used without a decoupling capacitor. I've been told the (non-public)
>     data sheet is rather sparse on details about the analog part of the
>     chip, so this is a good an understanding as we're going to get.

The datasheet is sparse yes but we have technical contacts at conexant 
who can answer your questions.  The DC input mode was part of our early 
discussions with them and its supposed to work at least as good as the 
last chip did.  I specifically remember asking them about this and 
telling them it was something to test in our early reviews of the 
hardware.   It should work.  If not then we need to know why so we can 
prevent it from happening on the 1.75.

If you will frame up your questions with good detailed descriptions on 
how to duplicate the problems you are having I'll see that it makes it 
to conexant for testing and feedback and make sure they have the proper 
hardware to test it on.

Richard A. Smith  <richard at laptop.org>
One Laptop per Child

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