Board Power Supply - Digilent chipKIT Pro MX7 Reference Manual

chipKIT™ Pro MX7 Board Reference Manual
The PIC32MX5XX/6XX/7XX Family Data Sheet and the PIC32MX Family Reference Manual are available from the
Microchip web site: www.microchip.com
Reference material for the MPIDE system is included in the MPIDE software download and on-line in the chipKIT
wiki. Help with questions and problems using the board with the MPIDE software can also be obtained in the
chipKIT forums:
www.github.com/chipKIT32
www.chipKIT.org/wiki
www.chipKIT.org/forum
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Board Power Supply

Switch SW1 in the lower left corner of the board is the power switch. Place this switch in the ON position to turn
on board power and in the OFF position to turn off board power.
The chipKIT Pro MX7 may be USB powered via either the USB debug port, the USB UART port, or the USB device
port. Alternatively, the board may be powered via dedicated "external" power supply connectors.
Jumper block J3 selects the power source used to provide power to the board. This jumper block provides the
following four positions:
 USB – power is supplied by USB device connector J19. This is used when the chipKIT Pro MX7 is being used to
implement a USB bus powered device.
 EXT – Power is supplied by one of the external power connectors.
 DBG – Power is supplied by DEBUG USB connector J15.
 UART – Power is supplied by UART USB connector J2.
Place the shorting block in the appropriate position on J3 for the desired power source for the board.
The chipKIT Pro MX7 is rated for external power from 3.6 to 5.5 volts DC. Using a voltage outside this range will
damage the board and connected devices. For most purposes when using external power, a regulated 5V supply
should be used. If the board is operated from an external supply with a voltage less than 5V, some features won't
work correctly.
The USB specification requires that USB devices not draw more than 100mA of current until they have enumerated
on the USB bus and informed the host that they want to consume more current. To meet this specification, the
debugger circuit turns on main board power by driving the PWR_ON signal high after successfully enumerating on
the USB bus. The bus labeled on the schematic as VCC5V0 is powered when this occurs. The VCC5V0 bus powers
the input to the main board voltage regulator, the input voltage to the USB bus voltage load switch used when
using the board as a USB host, the power supply voltage for the CAN transceivers, and the 5V0 side of the power
select jumpers for the Pmod ports. The voltage on the VCC5V0 bus will be 5V when the board is being operated
from USB power or an external regulated 5V supply. If a different external supply voltage is used, that voltage will
appear on the VCC5V0 bus.
The power supply selected by the shorting block on J3 will appear on the input power supply bus, labeled VIN in
the schematic. This voltage is regulated to 3.3V to power the licensed debugger circuit by IC11, a Microchip
MCP1801 Low Dropout voltage regulator. This regulator is turned on and the debugger circuit is powered
whenever the power switch is in the on position. The VIN power bus also supplies power to IC9, a PFET load switch
used to turn main board power on or off.
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