Usb sch
mcu section
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I have got the chip analysis done from the MCU vendors and it shows the xray and I can see that the internai wires D+, D- and some other IO pins are cut
It also shows that the internal diodes (TVS I think) are damaged and hence the short.
I too think it probably is the ESD but i have the protection
Below are the PCB Design section
TOP LAYER
On Top the series resistors are used on D+ and D-
BOTTOM LAYER
On Bottom layer I have the ESD Chip and the fuse.
I understand that the ESD pins have to be connected without a Via, Preffered is always a direct connection but due to the PCB and placement constraint, I had to place it as given
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SHIELD GND AND USB GND are saparted as given below
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My Power Supply Circuit. The voltages that I get are perfect and there is no fluctuation or ringing on DC to DC.
The 3.3V from the regulator is directly connected to MCU Power. with some 0.1uF caps
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Note: I am not using USB power to run the system. The device is powered by a battery
VBus is used only for USB Detection Purpose