We are having continued issues with a prototype design using these parts.
The first issue seems to be resolved by connecting pin 3 (Host) to 3V3 vs ground as stipulated in the data sheet
http://focus.ti.com/lit/ds/symlink/pcm2706.pdf (page 29)
more so wanting to bring this to your attention
The second issue that has not been resolved yet is that the right analog channel does not work on multiple boards (every one that has Host tied high- the rest dont work at all)
are there any known issues/ causes for this? It does output the 1.65 DC bias correctly
Thank you,
Peter
Is the device self-powered or host-powered? Do you use custom descriptors?
Is it possible to get an excerpt of your schematics that show how the PCM2706 is hooked up to the USB bus & the power supply?
There are no know issues w.r.t. right analog channel problems.
Than you for the reply.
aipapps Is the device self-powered or host-powered? Do you use custom descriptors?
it is bus powered. No custom descriptors yet.
aipapps Is it possible to get an excerpt of your schematics that show how the PCM2706 is hooked up to the USB bus & the power supply? There are no know issues w.r.t. right analog channel problems.
http://www.2shared.com/file/5784185/62b6e81e/PCM2706_schematic.html
It is laid out per pg.29 on data sheet. The rest of the board is not populated so there is no unexpected behavior on the function pins.
Clock powers on consistently.
Also, pulling pin 3 high (500mA mode) did not provide a viable solution after all. Next day all four boards did not work and are now intermitently recognized.
If there are no known issues it must be a layout issue or clock issue I would imagine. Any recomendations?
Thank you
Here is some more info on the issues we are having...
This is a screen capture from SnoopyPro, a USB bus sniffer. Note the two packets at the end. The error says No Configuration Present => unconfigure device! This happens after successful configuration and about 200 successful isochronous transfers. Sometimes, the successful isochronous transfers do not occur and the error message appears immediately following an apparently successful configuration.
http://www.2shared.com/file/5784437/69879212/pcm2707error.html
In your schematics, the net labeled "3V3" is not driven by an external regulator, correct? (it must not be driven. No other pins besides the ones from the PCM2706 that your schematics show must be connected to that net).
The 10uF capacitor (C26) on the VBUS line can cause problems (but won't explain the errors reported by USB bus sniffer). Can you try to remove this capacitor, please?
The schematics you provided look correct.
There is no external regulator.
It seems we have resolved the issue by using a different oscillator circuit . We will probably respin the prototypes with clock ICs though.