I’d like to power my Tracker SOM Evaluation Board using a 12V power supply. There is a connector (connector 13 Tracker SoM Evaluation Board | Datasheets | Particle)
I can’t find any details on the connector. Am I missing something?
Is there another way to easily power the device from a 12V supply?
Yes, you can power the eval board from the VIN barrel connector.
Asking here because I'm limited to 5 questions per topic. Follow-up on question 3:
I don't see how power can be removed from the cellular modem: it's connected directly to VSYS+, which comes from the PMIC. Removing power is a dangerous thing to do unless all I/O can tolerate input voltages when VCC = 0. Example: CELL_RXD, CELL_TXD, CELL_CTS, CELL_RTS. If power is removed, can these signals be driven to 3.3V? Also, since VSYS+ can be as high as 4.35V (BQ24195 datasheet), will the nRF52840 be able to tolerate I/O voltages this high? nRF52840 datasheet, section 9: absolute maximum VIO is VDD + 0.3V = 3.6V.
The modem VCC can accept up to the VSYS maximum voltage. The cellular modem uses 1.8V logic and there's a SN74AVC4T774 level shifter, which is powered by 3V3 and VDD_EXT, which is an output from the cellular modem, and supplies the 1.8V rail.
The 3V3 rail cannot be externally powered on the Tracker SoM. 3V3 is only powered from the 3.3V regulator, which is powered from VSYS.
The nRF52 is powered from 3V3, so it will always be less than 3.6V.
More questions:
The Tracker SoM is not AEC-Q100 qualified. The Tracker SoM itself was not vibration tested, but the Tracker One (which contains the Tracker SoM) was tested for ISO 16750-3-2012.
The Tracker Edge software implements charge control based on temperature, both high and low.
The bq24195 PMIC on the Tracker SoM theoretically supports hardware charge control based on a pack thermistor but this cannot be used on the Tracker SoM.
Follow-up on 2: PMIC R23 and R24 resistive divider TS is available on pin 46. Can a thermistor be used? If yes, what is the part number?
Also, please clarify "The Tracker Edge software implements charge control based on temperature, both high and low." Does the software exclude charging below 0C and if yes which IC on the Tracker SOM measures the temperature?
You cannot add the pack thermistor on the TS line. The reason is that the bq24195 does not have the ability to disable the pack thermistor if not present. The resistor divider simulates a thermistor at normal charging temperature. There's no combination of resistors you can add to make it work normally again, short of removing the two SMD resistors already connected to the pin on the SoM.
There's a thermistor on the Tracker One carrier board that's used for charge temperature control in software.
We are designing a board using the Tracker SOM. Is the thermistor connected to A0?