DS51795A Datasheet, PDF (73/98 Pages) Microchip Technology – PICkit™ 3 Programmer/Debugger

Operational Advisory
peripherals and pins which are common to the default PGC/PGD pins, you must select
a different channel and make provisions for the required ICSP connections.
Likewise, when using MPLAB IDE to communicate with the target using this new chan-
nel pin assignment, you must ensure that the Configuration bits in MPLAB IDE match
the connection channel in your target.
GROUNDING AND AC APPLICATIONS
PICkit 3 connects to earth ground from the USB connector interface through the PC.
For AC line powered applications which are not referenced to ground, this presents a
path where the different system voltage potential can cause damage to both systems.
In these instances, the PICkit 3 must be isolated. Carefully consider the ground system
and signal return connections before connecting the PICkit 3 to the target.
For hot or floating applications, a USB self-powered isolated hub should be used
between the PC and the PICkit 3 to provide isolation from the PC’s earth ground
through the USB cable (see Figure B-2). USB isolated Hub such as the following are
suggestions:
• High/Low-Speed 4-port USB HUB, Model UISOHUB 4, B&B Electronics Mfg. Co.
• High-Speed, 7-port USB HUB, Model HUB7P, SEALEVEL Systems, Inc.
WARNING
Using the PICkit 3 without ensuring ground isolation will result in
damage to the PICkit 3 or the target system as the full AC mains
voltage will be applied.
This condition can be hazardous to the operator in the form of an
electric shock. Therefore, take adequate precautions to avoid this
situation.
FIGURE B-2:
EXAMPLE PICKIT™ 3 SETUP FOR NON-ISOLATED AC
POWER SYSTEMS
Optoisolated
Self-Powered
Target
USB Hub
PICkit 3
Application
PC
Target
A/C
Ground
A/C
Earth Ground
HOT
WARNING
Using an optoisolated USB hub will create a hot area marked with the
dotted line in Figure B-2.
This condition can be hazardous to the operator in the form of an
electric shock, therefore, take adequate precautions to avoid this
situation.
© 2009 Microchip Technology Inc.
DS51795A-page 69