Input USB voltage question for the Boron

Quick question about the USB port on the Boron, when powering the Boron via the micro USB port what is the input voltage variance that it will tolerate from the wall power adapters?

I may have answered my own question from the data sheet:

Which means that whether the external charger is 5V (ex: Apple A1385) or 5.2V (ex: Apple A1401), either would be fine and both match the minimum current requirement of 500mA minimum.

Please post if I missed something important in this analysis. Thanks

If you are using a USB output power adaptor then you would expect it to conform to the USB standard -

USB supplies power at 5 V ± 5% to power USB downstream devices. To allow for voltage drops, the voltage at the hub port is specified in the range 5.00+0.25
−0.60 V by USB 2.0, and 5.00+0.25
−0.55 V[40] by USB 3.0.

The VUSB pin on the Boron is the Vin referred to not the micro USB connection.

Summary - you are fine to use a USB adaptor via the micro USB, you need to be more careful when supplying power to the VUSB/VIN pin and also not have micro USB powered at the same time.

Thanks and really good point about the USB standard. I was actually surprised to see printed on the A1401 that the output was 5.2V and not 5.0V,

Quick follow-up question, what would be the lowest minimum current draw to program for the PMIC during battery charging, given the potential for any off-the-shelf USB charger to be used?

I don’t understand this conflicting information.

The following thread states Particle has claimed the Boron can take up to 17V on VUSB:

However this thread states Particle has claimed the Boron can only take up to 6.2v on VUSB.

This is a very problematic confusion for me as I am currently dealing with Boron power/eventual crashing issues which more and more seem to be not because I am doing anything incorrectly.

What is the maximum input voltage on Particle Boron VUSB: 6.2v, or 17v?

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I agree that this is very confusing. Maybe @rickkas7 can chime in and clarify why the docs state 6.2V as max Vin while the schematic and the BQ24195L datasheet would suggest an input range of 3.9V to 17V.

This might just be an oversight on the differences between Gen3 devices where the Argon/Xenon specs are incorrectly also shown for the Boron.

For Argon and Xenon 6.2V should be considered the absolute max input du to the XC9258 regulator’s specs.
But the BQ24195L is much more capable and hence can also take higher input voltage.

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@Paul_M & @ScruffR

Yeah, I’d love a clear answer on the max VUSB voltage for the Boron as well. The docs do show that 6.2V max but many threads here have people talking about using 12V panels w/ no problems.

I have 6V 9W and 18V 9W panels. The 6V should be fine, but I’d really like to know the “real” absolute max upper limit on VUSB.