
REF: BB_SRM_xM BeagleBoard-xM System
Reference Manual
Revision A2
Page 60 of 164
protection (short-circuit). The VAUX2 LDO is powered from the main VBAT rail. The
VMMC1 rail defaults to 3.0V as directed by the TPS65950 boot pins and will deliver up
to 220mA. The voltage rail is labeled VDD_EHCI on the schematic.
8.8.10 EXP_VDD
The EXP_VDD rail uses the VAUX1.OUT rail from the TP65950. EXP_VDD is
adjustable from 2.5 to 3.0V and can deliver up to 200mA of current. EXP_VDD is
provided as an auxiliary voltage rail on P13, the LCD Expansion Header. The proper
setting of this rail is determined by the application and the HW supplied that connects to
P13.
8.9 Other Signals
This section describes other signals in the design that have not been categorized.
8.9.1 Boot Configuration
The boot configuration pins on the TPS65950 determine the power sequence of the
device. For the AM3730 support, the boot pin configuration is fixed at:
o BOOT0 tied to VBAT
o BOOT1 tied to Ground.
8.9.2 RTC Backup Battery
An optional battery to backup for the Real Time Clock that is in the TPS65950 is
provided for in the design. The board does not come equipped with the battery. The
battery can be purchased from DigiKey or other component suppliers. When the battery
is not installed, R66 must be installed. You must make sure that prior to installing the
battery that R66 is removed.
Refer to section 9.11 for information on the battery selection and installation.
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