DS51795A Datasheet, PDF (22/98 Pages) Microchip Technology – PICkit™ 3 Programmer/Debugger

PICkit™ 3 User’s Guide
FIGURE 2-4:
STANDARD CONNECTION TARGET CIRCUITRY
Application
PC Board
VDD
Device
VPP/MCLR
PGC
PGD
AVDD ^VSS
AVSS
User Reset
4.7K-10K
2
1
5
4
3
Interface
Connector
2.4.3 Target Powered
In the following descriptions, only three lines are active and relevant to core debugger
operation: pins 1 (VPP/MCLR), 5 (PGC) and 4 (PGD). Pins 2 (VDD) and 3 (VSS) are
shown on Figure 2-4 for completeness. PICkit 3 has two configurations for powering
the target device: internal debugger and external target power.
The recommended source of power is external and derived from the target application.
In this configuration, target VDD is sensed by the debugger to allow level translation for
the target low voltage operation. If the debugger does not sense voltage on its VDD line
(pin 2 of the interface connector), it will not operate.
2.4.4 Debugger Powered
The internal debugger power is limited to 30 mA. This may be of benefit for very small
applications that have the device VDD separated from the rest of the application circuit
for independent programming, but is not recommended for general usage as it imposes
more current demands from the USB power system derived from the PC.
Not all devices have the AVDD and AVSS lines, but if they are present on the target
device, all must be connected to the appropriate levels in order for the debugger to
operate. They cannot be left floating.
In general, it is recommended that all VDD/AVDD and VSS/AVSS lines be connected to
the appropriate levels. Also, devices with a VCAP line (PIC18FXXJ for example) should
be connected to the appropriate capacitor or level.
Note:
The interconnection is very simple. Any problems experienced are often
caused by other connections or components on these critical lines that
interfere with the operation of the PICkit 3 programmer/debugger, as
discussed in the following section.
DS51795A-page 18
© 2009 Microchip Technology Inc.