User's Manual

HE910 Hardware User Guide

1vv0300925 Rev.28 – 2015-06-24

9 USB Port

The HE910 includes one integrated universal serial bus (USB 2.0 HS) transceiver.

9.1 USB 2.0 HS Description

This port is compliant with the USB 2.0 HS.

The USB FS is supported for AT interface and data communication.

The following table is listing the available signals:

PAD

Signal I/O Function Type NOTE

B15

USB_D+ I/O USB differential Data (+) 3.3V

C15

USB_D- I/O USB differential Data (-) 3.3V

A13

VUSB AI

Power sense for the internal USB

transceiver.

Accepted range:

4.4V to 5.25V

The USB_DPLUS and USB_DMINUS signals have a clock rate of 480 MHz.

The signal traces should be routed carefully. Trace lengths, number of vias and capacitive

loading should be minimized. The characteristic impedance value should be as close as

possible to 90 Ohms differential.

In case there is a need to add an ESD protection the suggested connection is the following:

NOTE:

VUSB pin should be disconnected before activating the Power Saving Mode.

In case of a Firmware upgrade using the USB port, it could be done only using an USB 2.0 HS

device.