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K65P169M180SF5V2 GPIO Voltage Limits on Startup

Question asked by B Hofer on Nov 7, 2018
Latest reply on Nov 12, 2018 by B Hofer

Hi all!

 

Here is a question about the voltage limits of the K65P169M180SF5V2 GPIOs during startup.

Assuming that we have a peripheral powered with +5V and the K65 powered by an +3V3 LDO connected to this same +5V.

This periheral has a TX line connected via a voltage divider to an K65 GPIO that limits the input voltages to a safe level (max. ~3,3V).

In this situation the +5V can be present earlier at the voltage divider than the +3V3 supply at the K65, i.e. at startup the input voltage can be higher than the in datasheet specified VDIO_MAX  of VDD+0.3V.

Other posts (KL02 Min Max Input Current Voltage ) clarify that the K-Series does not have protection diodes to VDD.

Therefore I assume, that in this situation the K65 works outside the safe specification and can be damaged, even if the series resistor of the voltage divider limits the current (e.g. <1mA).

 

Is this view correct or can the K65 tolerate such transient events?

 

Kind regards,

 

B.Hofer

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