LG CU405 Service Manual page 42

CU405 have a protective circuit for booting from USB. When the phone is booting from USB_VBUS
without Battery, booting current is insufficient. Sometimes that can break the USB port of a computer.
For this reason, CU405 do not support booting from USB.
USB_VBUS
Copyright © 2007 LG Electronics. Inc. All right reserved.
Only for training and service purposes
Q500
4
5
KRX102E
Figure. Schematic of USB protective circuit
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3. TECHNICAL BRIEF
3
USB_VBUS_IN
2
PS_HOLD
1
LGE Internal Use Only