-Please provide a screenshot of the error you are getting. If you are getting a "Device Descriptor Request failed" every time, please refer to the KBA.
-In your schematics, kindly check if PWR#(Pin 26) is set as active high or low. Please add pull up or pull down resistors accordingly.
-It is recommended to not have resistors present on the DP/DM lines. You could use chokes(of insertion loss<1dB) instead if it is a noisy environment.
I have checked the KBA:
The USB data lines are 90 ohm lines with no resistors or capacitors.
The RESET pin is tied to VBUS through 10 K and pulled to ground through 1 µF and 47 K.
The crystal (Abracon ABM3C-12.000MHZ-D4Y-T) is close to the IC.
Parallel Fundamental Mode, 30 ppm, Rs 60 ohm, C0 = 7pF, CL = 18pF
Drive Level Typ 10 Max 100 µW (Your spec says 600 µW minimum drive level)
PWR# is pulled up by 47K.
Instead of screenshot from the Norwegian Windows 10, I have made translations:
A warning message at the lower right corner of the screen:
"Unknown USB device
The most recent USB-device connected
to this computer had a failure and
Windows does not know it"
The device manager shows a warning sign under "USB-controllers":
"Unknown USB device (Request for description failed)"
Right-clicking the warning and choosing "Properties":
Windows has stopped this device because it has reported problems (Code 43)
A request for the USB device descriptor failed.
A schematics was attached to my initial support request. Please check it.
Thank you so fare. Best regards
Jan Erik Nilsen
-Please check if your crystal power consumption with HX2VL is less than the maximum specification (100 uW) of your crystal.
-Could you please carry out Signal Integrity tests to see if they pass?
-Please check your layout as per the guidelines in AN72332.
- The crystal seems to be fine. 12MHz on XOUT. Oscillator stops when the device fails. Should it? Crystal drive Level Typ 10 Max 100 µW (Your spec says 600 µW minimum drive level).
- Signal integrity checked with the PCB designer. No issues found.
The problem is not solved.
I continue working with the problem. The PCB is checked. No issues found. No short-circuits. I have captured some signals with oscilloscope and made a PDF document with images and comments. How can I send it to you?
Jan Erik Nilsen
- Could tell me voltage levels on XIN and XOUT when the crystal stops working? If the maximum power is 100uW for your crystal, it should not be exceeded when connected to HX2VL.
-Kindly attach the pdf document using the Advanced editor option. You could also send it over private message option if there is some confidential data.
Voltage levels p-p XOUT = 0 - 3.2, XIN 0.32 - 2.5. This applies until the oscillator stops.
Crystal freq. tolerance = +/- 30 ppm, CL = 18 pF, Drive Level = 10 µW typ, 100 µW max.
See attached pdf file
CY7C65642-28 problem.pdf 267.4 K
1 of 1 people found this helpful
Yesterday I found the problem.
The ESD protection (Littlefuse SP0503BAHTG) chokes the USB signals due to high capacitance (30pF).
It will be replaced by Littlefuse PGB1010603MR.