User's Manual

EHS5-E/EHS5-US Hardware Interface Overview
2 Interface Characteristics
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EHS5_HIO_v01.000 Page 10 of 35 2012-11-14
Confidential / Preliminary

2 Interface Characteristics
EHS5-E/EHS5-US is equipped with an SMT application interface that connects to the external
application. The SMT application interface incorporates the various application interfaces as
well as the RF antenna interface.
2.1 Application Interface
2.1.1 USB Interface
EHS5-E/EHS5-US supports a USB 2.0 High Speed (480Mbit/s) device interface that is Full
Speed (12Mbit/s) compliant. The USB interface is primarily intended for use as command and
data interface and for downloading firmware.
The USB host is responsible for supplying the VUSB_IN line. This line is for voltage detection
only. The USB part (driver and transceiver) is supplied by means of BATT+. This is because
EHS5-E/EHS5-US is designed as a self-powered device compliant with the “Universal Serial
Bus Specification Revision 2.0”
1
.
Figure 2: USB circuit
To properly connect the module's USB interface to the host a USB 2.0 compatible connector is
required. Furthermore, the USB modem driver distributed with EHS5-E/EHS5-US needs to be
installed.
1. The specification is ready for download on http://www.usb.org/developers/docs/
VBUS
DP
DN
VREG (3V075)
BATT+
USB_DP
2)
lin. reg.
GND
Module
Detection only
VUSB_IN
USB part
1)
RING0
Host wakeup
1)
All serial (including R
S
) and pull-up resistors for data lines are implemented.
USB_DN
2)
2)
If the USB interface is operated in High Speed mode (480MHz), it is recommended to take
special care routing the data lines USB_DP and USB_DN. Application layout should in this
case implement a differential impedance of 90Ohm for proper signal integrity.
R
S
R
S
SMT