I am trying to power the Sodaq ONE from a wall power pack. The reason why is because I also need to power a sensor, which requires +/- 12V.
Unfortunately, I can’t seem to get the Sodaq ONE to turn on, despite the correct voltage being applied to the pins.
Here is the layout of the circuit:
I have a switching regulator from 12V DC to 28V DC. I am then using a rail splitter (TLE2426) to get a regulated +14V, 0V and -14V outputs.
Between the 14V and 0V outputs I am using voltage divider to provide 4V to the board. I am running this through some decoupling capacitors also.
I have confirmed that there is definitely 4V running into the V_Batt pin. This is the same voltage that is being output of my Li-Ion battery. When I plug in the Li-Ion battery, the Sodaq ONE powers up. However, when I plug in the power pack it does not. Despite there being the same voltage on the pins.
I have also tried using 3.7V through to 4.6V. I have also tried plugging this voltage source into the V_SOLAR pin as well, but there is no difference.
The Power supply can provide 1.5A, the boost regulator can provide up to 2A output. And the TLE2426 rail splitter can provide up to 7A. So I have ruled out a lack of current to power up the board.
The schematic for the power supply circuit is below:
V_In and V_GND are going to V_Batt and GND on the Sodaq respectively.
Edit: I have calculated that 1.5A (from the PSU) would be converted to 640mA after upconverting the voltage with the Boost converter. the SAMD21 datasheet states 90mA current requirements. I would have thought 640mA would have been enough to start the Sodaq ONE board.
Edit 2: I measured the current at the output (V_BATT) and it was only 2.5mA. I think that my DC-DC boost converter is losing way too much current. I am re-designing the circuit to work with a 48V plugpack instead of a 12V one.