DC power/plug pack to power Sodaq ONE

ONE
#1

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.

CurrentSensorPSU_Schematic1.png1044×237 20.1 KB

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.

#2

Did you check this page?
http://support.sodaq.com/sodaq-one/battery/

#3

Yes I did. The Board turned on when using a 3.7V battery.
The problem ended up being that my DC-DC converter was chewing up all the available current.

#4

I’m still having an issue with this. I’ve used a 24V power supply, split the rails into +/- 12V with Virtual ground and then used a voltage divider to source 3.9V from +12V / V_GND.

The power supply is capable of sourcing 2.5A, so it’s not a current problem this time. When I measure the V_BATT and GND terminals without the SODAQ plugged in I have 3.9V across the terminals, as expected. However, when I plug in the SODAQ and measure across the terminals there is only 1.3V.

Why would the voltage across the V_BATT and GND terminals drop from 3.9V to 1.3V when plugging in the SODAQ?

Once again, the SODAQ will not turn on, this time I predict it has something to do with the voltage dropping to 1.3V.
Yes, I have read the ‘battery’ page that you linked, and I have a jumper placed between pins 4 and 5 to enable start up.

Thanks

#5

If anybody wants to know the solution to this its because I was using a resistor voltage divider. Instead, I switched to a zener diode divider and added an NPN transistor to source more current from the power supply to avoid that current burning up the series resistor.