is there any polarity protection in nRF52832?

[RAJESHKUMAR C]

Hi,

I am developing a small development board of visiting card size, which is powered from a coin cell. I have two questions,

1. All i want know is there any polarity protection at the VCC of the nRF52832?
2. What will happen if the battery polarity is reversed?

[MartinBL]

Hi,

1. Unfortunately there is not. So I would recommend that you implement external reverse voltage protection if there is a chance that you or your customers might reverse the polarity by accident. Here are a couple of suggestions for circuits: Reverse-Current Circuitry Protection.
2. Hard to say. Undefined things. Most likely the nRF52 won't like it.

[AmbystomaLabs]

If you do some testing what you will find is when you reverse bias an nRF, like most processors, all the fets that make up gpio and other stuff turn on and short vdd to vss. Since a button cell has very high esr the most current it can put out is about 15mA and it is unlikely the nRF will suffer any damage. The battery however will be fully discharged quickly. And, yes I have done this by accident a few times.

If instead you are using a battery with low esr, such as alkaline, then those can easily source an amp and the nRF would be damaged.

If you are still determined to put in reverse bias protection, I would suggest you choose the ESD style with reverse biased diode. Since no run current goes through the diode there is no power loss unlike a series diode solution when you get forward voltage drop and power loss. Leakage current on a diode is normally in the picoamps. Same as earlier though the battery still goes flat when you put it in backwards.

[RAJESHKUMAR C]

Hi AmbystomaLabs,

Thanks for your valuable suggestion in this, since it is a development board I go with series diode solution. At product level the reverse bias protection solution would be valuable one.

[RAJESHKUMAR C]

Hi Martin,

Thanks for the Link.