Maximum VIN for Particle Boron

boron
Tags: #<Tag:0x00007fe21ebe6268>

#1

I recently purchased a Boron and want to use it in an application where the mains DC power input is at 12-15V.
I studied the schematic and see that

  1. the VUSB pin 3 on the header CONN2 is connected to the VBUS pins of the BQ24195
  2. BQ24195 states up to 17V permissible bus voltage
  3. the VBUS_NRF pin of the microUSB connector is protected from reverse polarity by a diode
  4. all three capacitors (C57, C60, C64) on the VIN net are rated at 25V

That said, is it safe to connect the 15V directly to the VUSB pin though the docs of the Boron specifiy a recommended/max/absolute max of 3.3V/3.6V/6.2V?


#2

VUSB maximum is 6.2V with this rider

Stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under recommended operating conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

Typical VUSB is 5V - best to stick to this for a long and reliable operation! Generally a good clean DC PSU will pay back the cost.


#3

Agreed, that’s what the docs say. However, nothing on that net has a 6.2V absolute maximum, as far as I can see, so I don’t understand where that figure comes from.
The BQ24195 datasheet clearly states a 3.9-17V permissible bus voltage.


#4

I’ve run 12.5 volts no dramas. If I recall, you can’t power the boron by VIN and USB at the same time or it will blow the USB side of things.


#5

@ric_hard, glad to hear that. With the 12V capable VBUS, I can completely eliminate any regulators from my board and directly feed in the external DC adapter power.