beaglebone-black - Flipbook - Page 41
BeagleBone Black
In power o昀昀 mode, the RTC rail is still active, keeping the RTC powered and running o昀昀 the main power input. If
you remove that power, then the RTC will not be powered. You also have the option of using the battery holes
on the board to connect a battery if desired as discussed in the next section.
If you push and hold the button for greater than 8 seconds, the PMIC will power down. But you must release
the button when the power LED turns o昀昀. Holding the button past that point will cause the board to power
cycle.
6.1.6 Battery Access Pads
Four pads are provided on the board to allow access to the battery pins on the TPS65217C. The pads can be
loaded with a 4x4 header or you may just wire a battery into the pads. In addition they could provide access
via a cape if desired. The four signals are listed below in table-3 .
Table 6.1: BeagleBone Black Battery Pins
PIN
DESIGNATION
FUNCTION
BAT
SENSE
TS
TP5
TP6
TP7
GND
TP8
Battery connection point
Battery voltage sense input, connect to BAT directly at the battery terminal.
Temperature sense input. Connect to NTC thermistor to sense battery temperature.
System ground.
There is no fuel gauge function provided by the TPS65217C. That would need to be added if that function was
required. If you want to add a fuel gauge, an option is to use 1-wire SPI or I2C device. You will need to add this
using the expansion headers and place it on an expansion board.
NOTE: Refer to the TPS65217C documentation + before connecting anything to these pins.
6.1.7 Power Consumption
The power consumption of the board varies based on power scenarios and the board boot processes. Measurements were taken with the board in the following con昀椀guration:
• DC powered and USB powered
• HDMI monitor connected
• USB HUB
• 4GB USB 昀氀ash drive
• Ethernet connected @ 100M
• Serial debug cable connected
Table 6.2: BeagleBone Black Power Consumption(mA@5V)
MODE
USB
DC
DC+USB
Reset
Idling @ UBoot
Kernel Booting (Peak)
Kernel Idling
Kernel Idling Display Blank
Loading a Webpage
TBD
210
460
350
280
430
TBD
210
460
350
280
430
TBD
210
460
350
280
430
The current will 昀氀uctuate as various activates occur, such as the LEDs on and microSD/eMMC accesses.
36
Chapter 6. Detailed Hardware Design
