When I connect the board to my computer, or any 5V power source with micro-USB, the board gets powered with 5V from the micro-USB. But is this the direct line to the +5V out pin? I have one SG90 micro servo, which needs to be powered. My USB power source could handle that power. But can I draw the current from the +5V pin? Or is there a weak regulator inbetween?
This would indeed imply that drawing current from the +5V out pin stresses the USB power source (computer or whatever) and not the Arduino. An USB power source might handle 2A. The traces on the Arduino might get hot and the servo motor might get damaged, but no semiconductors on the Arduino should get harmed. I could add an old fashioned slow fuse somewhere, say if the servo gets stucked.
The power scheme for the Mega is quite different from the MKR 1000 so using some justification for power usage for the Mega does not apply to the MKR or any Arduinos
Arduino does not specify a safe current draw for the 5V pin on the MKR but I would be hesitent to draw any more than 750mA
Or is there a weak regulator inbetween?
No but there are at least 2 MOSFETs and maybe an inductor.
If you have a USB power source that can supply enough current for the servo, then just connect it directly to the servo.
I don't see an inductor, probably it's a switching power with a closed loop with power sourced either from VUSB or Vin going through the 2 mosfet and using the 2N7002DW for switching?
Vin: This pin can be used to power the board with a regulated 5V source. If the power is fed through this pin, the USB power source is disconnected. This is the only way you can supply 5v (range is 5V to maximum 6V) to the board not using USB.
A set of AA batteries doesn't count as regulated, right? I have four of them and the servo runs just fine. But I can't power the MKR1000 with them. My multimeter measures 6.3 V with four fresh AA batteries.
