PCM2705 problem

[Ipanema]

I just build PCM2705 USB DAC following TI datasheet schematic on page 28 with bus power.

http://focus.ti.com/lit/ds/symlink/pcm2707.pdf

This USB DAC works perfectly fine the first time I plug them into PC. Windows(both XP and Vista) recognize them automatically and it can play music when plug into my system. But Windows refused to recognized it after I unplugged and replugged the USB cable on my PC. I have replaced PCM2705 three times. It always work fine the first time and refuse to work subsequently. What cause the chip to malfunction?

FYI, I built this DAC using SOIC to DIP converter using all through hole components. Apart from TI shcematic, I add 2200uF capacitor directly on the 5V USB VCC on board. Removing the big caps does not make any difference.

Thanks.

 

[adi]

Did you test it in another PC. It maybe OS problem.

 

[Ipanema]

I've tried it at both desktop PC (Windows XP) and laptop (Windows Vista). It is always detected the first time I plug it into PC. But the subsequent time plug-in, it is just not recognize by the PC "USB Device Not Recognized". It seems like the chip is malfuction or something because whenever I changed a new chip it will work again for the first time but will stop working the next time. Already change 3 chips. Pls advise.

 

[Neil Davis]

I've tried it at both desktop PC (Windows XP) and laptop (Windows Vista). It is always detected the first time I plug it into PC. But the subsequent time plug-in, it is just not recognize by the PC "USB Device Not Recognized". It seems like the chip is malfuction or something because whenever I changed a new chip it will work again for the first time but will stop working the next time. Already change 3 chips. Pls advise.

The USB bus senses attachment whenever it sees that pullup on D+. Are you sure that R2 is the right value (1.5K)? Also, R9 is required on the PCM2705 to make sure there is no data on DT that could corrupt the descriptor data. Just guessing--good luck.