MK22 GPIO voltage violation

[mizrachidan]

 

Hi all,

My MK22FX512AVLK12 was getting a negative voltage (by undershoot) of -1.5v (abs. max. rating by DS is -0.3v) for a period of about 0.4us

. 

After adding a capacitor the undershoot has reduced to -0.65v for  a period of about 1.3us.

 

Does both cases in fact causing voltage violation, or this is short enough time period so it wouldn't be harmful for the controller?  

thanks,

Idan

[Miguel04]

Hi @mizrachidan 

Any negative value further the specification could cause harm to the microcontroller.

You are using the GPIO as an input, correct?

How are you measuring the voltage?

You could correct the negative voltages adding a diode to allow only positive voltages. However, your values will be affected by this.

Let me know if you have another question.

Best Regards, Miguel.

[mizrachidan]

Hi Miguel,

Thanks for the reply.

I'm indeed using this GPIO as an input, and measure the voltage using Keysight DSOX1204G right at the uC pin.

I understand and agree that this problem should be solved better, but  was wondering if both cases are necessarily violating the uC, or can it obtain that negative voltage level (-0.65V) to this short time period (~1.4us) 

Thanks,

Idan

[Miguel04]

Hi @mizrachidan 

Independently of the period of time of the signal, any value that surpasses the limit can cause immediate or long term harm to the microcontroller, so I suggest you to protect your board with any type of rectifier.

Let me know if you have any other question.

Best Regards, Miguel.