3.2 Power Supply

The board can be powered through the USB port or by a CR2032 battery. It will automatically switch to the battery if USB power is not available. While powered through USB, the board generates 3.3V for the debugger, PIC16LF18456, and peripherals. During battery operation, the PIC16LF18456 and peripherals run directly on the battery voltage, while the debugger is not powered.

Current drawn from the USB port is limited to 500 mA by a PTC resettable fuse.

Important: When powering the PIC-BLE board with a CR2032 battery, it is important to leave the PIC16LF18456 pins that connect to the CDC UART in Tri-State (Input) mode. This is to prevent the debugger from getting powered through its GPIO.
Figure 3-3. Power Supply Block Diagram
Info: On the mikroBUS socket, the +5V rail is powered from the USB port. Consequently, +5V will not be available when the board is powered from a battery.