I have a ucontroller powered through an AP2112 3.3v from 5v, but I already have a stable3.3v so here my question,
can I just feed 3.3v on the output pin 5 of the ap2112?
if I understand the ic when turn off have inside discharge resistors is this really, 60Ohm or is it going into some High resistor?
if I do that will I blow the AP2112 ?
I try to measure the input current ... I should see 55mA but no im more like 20mA who is the uctrl running...
I could not really understand the spec sheet on that...

 

The 60Ω discharge resistor is connected when the AP2112 is disabled via the enable pin. What would happen if the chip had no input but 3,3V applied to its output I don't know but I don't recommend it.

 

Well you could cut the pin if you really want to try it. The concern is whether the controller can handle the ripple. The beauty of the regulator is that it can easily handle the ripple on the input rail and provide a steady 3.3V. Often currents in controllers are pulsed (based on cycles) this will cause an average current to be measured lower than the peak current. Without the regulator you will need good capacitors for your operating frequency so that the voltage stays within the controller's tolerance.

 

A follow up question to this old thread:
I understand from [AlbertHall] above that just bypassing the AP2112 (ie. no i/p voltage, but 3.3v on its output) is not reccommended.
But would just bypassing the AP2112 3.3v ouput regulator (ie. by connecting it's input to it's output, both being suppled with 3.3v) in order to run at 3.3v be a workable solution (ie. is this likely to damage the AP2112 or not)?

 

Safer to cut the output pin or remove the AP2112 completely.