My application has a power button that pulls up to battery voltage (3.2-4.2V) to switch power into the system. It's also necessarily tied to a (heavily muxed) gpio pin with ~200ohm protection. When the system powers on, there is a short time before VDD regulator starts up that current will be injected into the gpio pin.
1. How much current can I safely inject into a gpio pin through the clamp diode -- only for a limited time (few ms) while VDD is coming up?
2. What is the risk of side effects (like latch up) if I inject current during system power up?