https://devzone.nordicsemi.com/f/nordic-q-a/43509/nrf51822-gpio-current-injectionMy application has a power button that pulls up to battery voltage (3.2-4.2V) to switch power into the system. It&#39;s also necessarily tied to a (heavily muxed) gpio pin with ~200ohm protection. When the system powers on, there is a short time before VDDen-USTelligent Community 13Tue, 12 Feb 2019 10:10:55 GMThttps://devzone.nordicsemi.com/thread/170564?ContentTypeID=1Tue, 12 Feb 2019 10:10:55 GMT137ad170-7792-4731-bb38-c0d22fbe4515:ff1efad3-b1d8-4390-9cea-0fe8081785f0Jared<p>Hi,</p> <p>Page 38 in the product specification specifies that the absolute maximum I/O voltage can not be higher than VDD + 0.3 V.&nbsp; You must therefore assure that the voltage doesn&#39;t exceed this limit. If not, you risk&nbsp;Electrical Overstress on the pin.&nbsp;</p> <p>Jared</p><div style="clear:both;"></div>