BeagleBoard XM C2, Reference Manual

Page: 76 / 163

REF: BB_SRM_xM
BeagleBoard-xM System
Reference Manual
Revision C2
Page 76 of 163
Table 9. USB OTG Charge Pump Pins
Signal Description Type Ball
CP.IN The charge pump input voltage. Connected to VBAT. Power R7
CP.CAPP The charge pump flying capacitor plus. O L14
CP.CAPM The charge pump flying capacitor minus. O T6
CP.GND The charge pump ground. GND R6
The charge pump is powered by the
VBAT voltage rail. The charge pump generates a
4.8-V (nominal) power supply voltage to the VBUS pin. The input voltage range is 2.7 V
to 4.5 V so the 4.2V VBAT is within this range. The charge pump operating frequency is
1 MHz. The charge pump integrates a short-circuit current limitation at 450 mA.
7.13.5 OTG USB Connector
The OTG USB interface is accessed through the miniAB USB connector. If you want to
use the OTG port as a USB Host,
pin 4 of the connector must be grounded. The -xM Rev
A version of Beagle provides jumper pad, J6 that allows for a small piece of solder to be
placed on the pads to perform this function. It should be noted that with the USB Host
port on the -xM Rev A Beagle, the need to convert the OTG port to a host mode is greatly
diminished.
7.13.6 OTG USB Protection
Each lead on the USB port has ESD protection. In order for the interface to meet the USB
2.0 Specification Eye Diagram, these protection devices must be low capacitance.
7.14 Onboard USB HUB
A new feature of the –xM board is the inclusion of an onboard USB 4 port hub with an
integrated 10/100 Ethernet. This section describes the design of the HUB and the
interface to the processor. This allows for the support of LS and FS USB devices without
the need for an external USB HUB.
Figure 36 is a high level block diagram of the system
design of the integrated HUB.