IC Digital Input Slew Rate for Detection?

[ACharnley]

I have a bootstrap circuit which feeds power to an IC. The IC then shuts it down and allows a buck to take over at the same point that the main load is enabled. When no power is detected for a period of time it goes into sleep and switches off the main bus.

To get sleep draw as low as possible I was intending to away with a comparator on the wake input (see schematic), but this will mean dealing with a large skew, and I'm wondering if IC's like PIC's have trouble detecting this as a digital signal (voltage is above required but edge detection won't see it)?

 

[Nigel Goodwin]

No idea what that circuit is supposed to do?, or in whatway it's supposed to be a 'bootstrap'? - but regardless, many recent PIC's have I/O pins that can be set as standard inputs, or as schmitt trigger inputs, neither are edge triggered, so you should be able to sort something out.

 

[ACharnley]

The reason I ask is I've had a PIC before with this situation and it wouldn't detect the voltage change (the pin in question was set to TTL mode/2V and it wouldn't detect 2.3v). Now I'm unsure if the pin was faulty, but thought I'd ask to see if others have encountered it.