SparkFun Forums

[matthewpw]

Hi!

I'm using a LD1117V33 voltage regulator (https://www.sparkfun.com/products/526) in my project which has the power supplied by 12V from flat-top 18650 Li-Ion batteries. The batteries are removable so that they can be swapped for fresh, but I'm worried about what happens if someone installs the batteries the wrong direction and reverses the polarity.

First, Is the Nano at risk for damage if the voltage regulator is fed the reverse polarity?

Second, if it's at risk, what kind of circuit would I need to add to protect it from the problem? Would it go before or after the regulatlor?

Thanks for your help!
Matthew

[YellowDog]

Reverse polarity on any of the three power inputs will cause damage to something on the board. (Either the vreg or battery charger ic) SparkFun doesn't specify which voltage regulator is used in the schematic so I can't say what over voltage protection there is but as long as you don't input more than 5 to 6 volts you should be fine. Maybe SparkFun can let us know what vreg is on the board so we know the max voltage on VIN but if it were me I'd say 5 volts max on VUSB and 4.3 volts max on VBAT to be safe. It's possible VIN may max out at 6 volts depending on which vreg they used.


UPDATE
Per the hookup guide, VIN is max 6 volts. I'd recommend building your own 5 volt voltage regulator circuit wirh polarity protection diodes that connect directly to VIN and ground. That way the artemis is always happy and protected.

[matthewpw]

Thank you!! -M