User Manual

element14 is a trademark of Premier Farnell plc 73

6.11 USB Host

The board is equipped with a single USB host interface accessible from a single USB Type

A female connector.

Figure 48

is the design of the USB Host circuitry.

Figure 48 USB Host Circuitry

6.11.1 Power Switch

is a switch that allows the power to the connector to be turned on or off by the

processor. It also has an over current detection that can alert the processor if the current

gets too high via the

USB1_OC

signal. The power is controlled by the

USB1_DRVBUS

signal from the processor.

6.11.2 ESD Protection

is the ESD protection for the signals that go to the connector.

6.11.3 Filter Options

FB7

and

FB8

were added to assist in passing the FCC emissions test. The

USB1_VBUS

signal is used by the processor to detect that the 5V is present on the connector.

FB7

populated and

FB8

is replaces with a .1 ohm resistor.