MCC iPort/USB 2, Руководство пользователя

Страница: 15 / 23

10
some reason (i.e., use of a two-prong power mains plug), the host computer power
supply ground will float to some unknown voltage potential.
Case 2 - Laptop Computers. Laptop computers present special ESD problems. Most
laptop computers use an external double-insulated mains power supply which is
NOT connected to the mains earth ground. This means that the laptop chassis is
floating at some unknown voltage potential.
In either case, upon connection to the I
2
C adapter and the target system, the host
computer will discharge energy through its USB or RS-232 port to the I
2
C adapter,
and on to the target system. This discharge could damage the host computer, I
2
C
adapter, and the target system.
4.2 Grounding Solutions
To avoid damage to the host computer, I
2
C adapter, or target system, follow these
instructions:
• Wear an earth grounded wrist strap, or discharge any static charge build-up,
when handling the I
2
C adapter or any target system devices.
• Ensure that both the host computer and target system are connected to a
common earth ground point.
• Make sure that all interconnections are made BEFORE applying power to the
host computer, I
2
C adapter, and target system.
• If you are using a laptop computer or host computer that is NOT connected to
mains earth ground, make a hard-wired connection from the host computer
(i.e., port connector shell) and the target system ground connector to a
common earth ground point.
• Avoid plugging and unplugging system components while the host computer
or target system is powered.
• Ensure that any devices connected to the target system are properly grounded
to the common earth ground point.
• If unsure how to properly ground system components, seek electrical expert
help.
WARNING : Any damage caused by Electrostatic Discharge (ESD) through
inadequate earth grounding is NOT covered under the warranty of this product.