User Guide

MPLAB
®
PICkit™ 4 User’s Guide
DS50002751C-page 18  2018 Microchip Technology Inc.
2.3.3 Target Powered
In the following descriptions, only three lines are active to core debugger operation:
pins 1 (V
PP/MCLR), 5 (PGC) and 4 (PGD). Pins 2 (VDD) and 3 (VSS) are shown on
Figure 2-4 for completeness. MPLAB PICkit 4 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
(see Figure 2-5). In this configuration, target V
DD is sensed by the debugger to allow
level translation for the target low voltage operation. If the debugger does not sense
voltage on its V
DD line (pin 2 of the interface connector), it will not operate.
FIGURE 2-5: TARGET POWERED FROM EXTERNAL SOURCE
2.3.4 Debugger Powered
If the target is powered through the debugger with an externally powered hub as shown
below, the power available to the target is limited to 50 mA.
FIGURE 2-6: TARGET POWERED THROUGH SELF-POWERED HUB
Not all devices have the AV
DD 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.
Also, devices with a V
CAP line (PIC18FXXJ for example) should be connected to the
appropriate capacitor or level.
External Power Supplied to Target
MPLAB PICkit 4
Micro-B USB
cable to computer
Target Board
MPLAB PICkit 4
Target Board
Hub
Micro-B USB
cable to Hub
to computer
USB cable
External Power Supplied to Hub
Max Power
to Target
is 50 mA
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 MPLAB PICkit 4 In-Circuit Debugger, as
discussed in the following section.