What is killing my pcm2707

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blacky77

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Joined 2011
#1
Hello,

I want to build a NOS DAC similar to Doedes Project on dddac.de. My Problem is that the circuit is working - but after repowering, I suddently get no more answers on the USB bus and the chip PCM2707 seems to be dead.
I replaced the 2707 and it worked again. After repowering, the chip again is dead.

I assume some problems in the voltage supply or so. Anyone has an idea?

Attached are the power supply and the dac circuit.
 

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#3
1. Use a wire instead of the L3, L5 inductance...
2. Also, check into "(3) D+ pull-up must not be activated (HIGH: 3.3V) while the device is detached from USB or power supply is not applied on VDD and VCCx. VBUS of USB (5V) can be used to detect USB power status"
 
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#4
And Gate

SoNic_real_one said:
1. Use a wire instead of the L3, L5 inductance...
2. Also, check into "(3) D+ pull-up must not be activated (HIGH: 3.3V) while the device is detached from USB or power supply is not applied on VDD and VCCx. VBUS of USB (5V) can be used to detect USB power status"
Click to expand...

Ah, that is the and gate some people have in the circuit. Ok - i'll try that. two more pcm 2707 left...

Does anyone exactly the reason why this is needed?

thanks
 
#9
Ok. Problem solved everything is working now with the third chip. In the end, the inductors in the USB path where the problem. In addition I found out that I did not connect the I2S right, so do not rely on the schematic posted above.

--Thanks for support.
 
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