Can I power Boron from 12v via VUSB/VBUS, charge Lipo, and use USB?

[RobotChicken]

Good evening friends.

Can I provide 12-14.x volts to the Boron via the VUSB pin and also use and charge a backup Lipo battery using the provided onboard charging and SOC / Fuel Gauge circuitry? There will be periodic inductive loads on the 12v battery, and charging activity too (14+ volts).

Looking at the datasheet for the BQ24195 it seems operating range is 3.9 - 17v, absolute maximums are a bit higher, and looking at the datasheet and the block diagram for the Boron it looks like it shouldn’t let the magic smoke out to power from 12-14.x volts AND use a lipo as a backup (I assume the IC will treat it the same as a regulated 5v USB power source). Approx: 12-14v -> VUSB / VIN on BQ24195 -> 3.3 regulator via SW and lipo via BAT.

1. What should I consider to protect the hardware (more heat sinks / cooling, voltage limiting components, additional regulator, etc.). How about reliability?

2. Is it correct to assume I won’t be able to put 12+v on VUSB pin and plug in and use USB (unless there’s no power line and it’s just data).

3. Are VUSB and VBUS the same pin?

Thanks!

[shanevanj]

Whilst the tech specs are valid - I would play safe and stick with the BORON’s stated specifications - why not get a simple buck convertor break out and add inline from the 12-14v. something like https://www.adafruit.com/product/1385 - simple easy and does not invalid the BORON warranty, plus it will clean up the supply line to the BORON ultimately making the end product more stable.

[kenmacd]

Doesn't directly answer your questions, but maybe these help:

Powering Boron using 12v

Yes. 12v should work on VUSB. I still don’t like how this is never stated explicitly in the docs. You would have to review the Boron schematic on your own and look at how the PMIC (BQ24195L) is connected to the board pins. Then you have to pull the BQ24195 datasheet and look at what that maximum spec is. Here you can see that VUSB labeled on the board is VIN on the schematic: [image] Here you can see that Vin is directly connected to the BQ24195L VBUS pin: [image] Normal operating voltage f…

Powering Boron using 12v

12V on a Xenon or Argon on VUSB will be immediately fatal to the device. Also do not power both VUSB and the micro USB connector at the same time on a Xenon or Argon. 12V on a Boron on VUSB will be OK, as long as you don’t have any other circuitry that is expecting VUSB to be 5V maximum. The reason is that the Boron has a more elaborate power manager IC (PMIC) that is basically the same as the Electron and E Series and can tolerate higher voltages.

I'm disappointed I can't do the same on my xenon.

[RobotChicken]

@kenmacd

I’m disappointed I can’t do the same on my xenon.

Good to know. Hadn't gotten to the point of checking Xenon or Argon datasheets. Luckily I plan to use lipo only on Xenons.

[RobotChicken]

My takeaway is that for a prototype I can probably get away with it, but for a more long term installation I should probably plan to include additional conversion / regulation circuitry. Thanks for the link, btw.