Hello,
I'm trying to build a USB audio converter with a PCM2900C, which will be used in a portable turntable.
For this purpose, I have assembled a small test circuit board which corresponds exactly to the wiring diagram on page 26/illustration 38.
When I connect the circuit to the USB, I always get the message "USB device not recognized".
Of course, I've already checked a lot of things: Internal voltages are all Ok, 1.5K pull-up available at D+, 22R-resistors in D+/D- lines, decoupling capacitors like specified etc.
After connecting to USB, the 12Mhz clock rate appears on the XTO pin for a short time. When the error message appears, the clock is off again, XTO is high.
When I reach the (D-) line with my finger, clock suddenly reappears.
Even if I connect the D-line 10K-resistance with the D+-line, the clock output is stable.
Does the clock have to be permanently present? or is the oscillator deactivated if no USB detection has taken place? The data sheet does not show such a mechanism in the block diagram.
What else could be the cause of my problem, what else should I try?
Nevertheless, I am convinced that the CM2900C is the right choice for our product.
Thank you very much
Wolfgang
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