4.5 Power Supply
The USB port powers the board. The input power is delayed to allow USB cable oscillations to die out. The delay is about 1 ms. VBUS is further limited to a 2 V/ms slew rate and is current limited to 500 mA by U202 (MIC2008).
Tip: Changing the values for C206 and R211 can alter the
slew rate and current limit set by U202.
The power supply consists of two LDO regulators, one to generate 3.3V for the on-board debugger and an adjustable LDO regulator for the target PIC18F56Q24 microcontroller and its peripherals. The voltage from a USB connector can vary between 4.4V and 5.25V (according to the USB specification) and will limit the maximum voltage supplied to the target. The figure below shows the entire power supply system on the PIC18F56Q24 Curiosity Nano.