burnout limitation and constant powers

[Gunrunner]

I checked the FAQ but didn't find the answer, so here's my question:

If I want a constant power to have the burnout limitation do I have to make the activation roll after I stop feeding END to the power, or after every phase the constant power is active?

I want to build a constant power that has a chance of burning out, but only after the character stops maintaining it, not every phase. If the latter part of my question is the correct answer, then how could I do that?

[Steve Long]

1. Per 5E 181, an Activation Roll is made every Phase, even for a Constant Power.

2. You apply a Limited Power of a type approved by your GM to properly define what you want.