...........continued
Debugger Signal
Target MCU
Description
VBUS
—
VBUS voltage for external use
VOFF
—
Voltage Off input. Disables the target regulator and
target voltage when pulled low.
VTG
—
Target voltage
GND
—
Common ground
Figure 4-3. Curiosity Nano Standard Pinout
USB
DEBUGGER
PS LED
NC
ID
CDC RX
CDC TX
DBG1
DBG2
VBUS
VOFF
DBG3
DBG0
GND
VTG
CURIOSITY NANO
4.3
Power Supply
The board is powered through the USB port and contains two LDO regulators, one to generate 3.3V for the on-board
debugger, and an adjustable LDO regulator for the target PIC18F16Q40 microcontroller and its peripherals. The
voltage from a USB connector can vary between 4.4V to 5.25V (according to the USB specification) and will limit the
maximum voltage to the target. The figure below shows the entire power supply system on PIC18F16Q40 Curiosity
Nano.
Figure 4-4. Power Supply Block Diagram
USB
Target
MCU
Power source
Cut strap
Power consumer
P3V3
DEBUGGER
Power converter
DEBUGGER
Regulator
VUSB
Target
Regulator
Power
Supply
strap
Adjust
Level
shifter
VLVL
VREG
I/O
I/O
GPIO
straps
I/O
On/Off
Measure
On/Off
ID system
#VOFF
PTC
Fuse
Power protection
VBUS
Target
Power
strap
VTG
4.3.1
Target Regulator
The target voltage regulator is a MIC5353 variable output LDO. The on-board debugger can adjust the voltage output
supplied to the board target section by manipulating the MIC5353’s feedback voltage. The hardware implementation
PIC18F16Q40 Curiosity Nano
Curiosity Nano
©
2020 Microchip Technology Inc.
User Guide
DS50003047A-page 15
