Usb Interfaces; Example - Connecting Hsusb0 To A Micro-B Type Usb Connector - Novatel OEM6 Series User Manual

E.1.7

USB Interfaces

The OEM638 provides three USB2.0 High Speed interfaces.
HSUSB0 is configured as a device and is capable of operating at High Speed (480Mbps). Full speed (12
Mbps) and Low Speed (1.5 Mbps).
HSUSB1 and HSUSB2 are host ports and are capable of High Speed (480 Mbps) operation only. If it is
desired to use the host ports with Full or Low Speed devices, a USB hub (with a transaction translator) is
required between the OEM638 and the USB device. These ports are designed with a 3.3 V CMOS-level
control output for an external 5 V power switch that will provide the power switching and current limit
protection.
It is imperative for signal integrity and EMI reasons that the differential data traces for each USB interface
be routed as a 90 Ω differential pair. Use of a small value common mode choke (as shown in Figure 83,
Example - Connecting HSUSB0 to a Micro-B Type USB Connector on Page 167) may improve the
radiated emissions performance. Small ferrite beads, ESD protection are shown on VBUS and UID lines
as a contingency against radiated emissions.
The "HSUSBx_VBUS" signals are only present so that the PHY on the OEM638 may monitor activity on
each bus and are required for operation, although they will only carry a few mA maximum. The traces for
VBUS and UID should be routed away from any high current switching nets and high frequency signals.
The common mode choke, ferrite beads and bypass capacitor should be placed as close as possible to
the USB connector.
If a Type B or Type mini-B USB connector is used for HSUSB0, the "HSUSB0_UID" pin from the
OEM638 should be left floating (as there is no pin on those variants of the USB connector to connect to).
If a Type micro-B connector is used, the "HSUSB0_UID" pin should be tied to the UID pin of the
connector (as shown below).
Figure 83: Example - Connecting HSUSB0 to a Micro-B Type USB Connector
OEM6 Family Installation and Operation User Manual Rev 7 167