beaglebone day
I got the beaglebone working successfully with my current rig.
Since I need 5V to boot up the beaglebone I swapped out the Simple Switcher with an LMR62014XMFE/NOPBLMR62014XMFE/NOPB Step Up regulator.
It came out of the box with a 11.8V output so I piggy backed one of the feedback resistors with a 200k trim pot and adjusted it to output 5.0V
I configured the bq24075T Battery Charger with DPPM to my needs;
EN1 = Vss, EN2 = Vdd to use Rlim setting
- 1A peak current input by adjusting Rlim to 1.6k
- 500mA peak fast charging current by adjusting 1.8k (Allowing 500mA always for beaglebone)
Configured SYSOFF to Vss for Automatic battery Switchover active
Testing was conducted to see if the beaglebone booted up
- from Li-Ion Battery - Worked!
- from Qi Wirless Power - Worked!
If the beaglebone remained operating when changing power source
- Qi Power removed with Li-Ion Battery remained connected (i.e. Battery Only)- Worked!
- Li-Ion Battery Power with Qi Power restored - Worked!
- Qi Power with Li-Ion Battery removed (i.e. Qi Power only) - Worked!
- Qi Power with Li-Ion battery reconnected - Worked!
To check the power being drawn I observed the transmitter's power supply ammeter.
It read a peak of .240A (x 19V) = 4.56W - Not too bad for a first attempt.
It shows that the input current limiting feature is working as planned.
These settings can be further tuned as required.
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