LGE Internal Use Only
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
4. TROUBLE SHOOTING
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4.9 USB Troubleshooting
USB Initial sequence of CU575 is :
USB connected to CU575 power on
→
USB_VBUS go to 5V
→
USB_D+ go to 3.3V
→
48M Crystal on
→
USB_VP and USB_VN is triggered
→
USB work.
Start
VA808(USB_VBUS)
is 5V?
VA810(USB_D+)
is 3.3V?
48M clock is running?
Change the main board
Check VA808
Check VA810
Check X201
NO
YES
YES
YES
NO
NO
Cable is inserted?
YES
Insert cable
NO
Power is on?
YES
Go to power on trouble shooting
NO