Microchip Technology MPLAB ICD 3 User Manual page 22

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MPLAB ICD 3 In-Circuit Debugger User's Guide
FIGURE 2-4:
2.5.3
In the following descriptions, only three lines are active and relevant to core debugger
operation: pins 1 (V
shown on Figure 2-4 for completeness. MPLAB ICD 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 V
the target low voltage operation. If the debugger does not sense voltage on its V
(pin 2 of the interface connector), it will not operate.
2.5.4
The internal debugger power is limited in two aspects: (1) the voltage range is not as
wide (3-5V); and (2) the amount of current it can supply is limited to 100 mA. This may
be of benefit for very small applications that have the device V
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.
Be aware that the target V
target low-voltage operation. If the debugger does not sense voltage on its V
2 of the interface connector), it will not operate.
Not all devices have the AV
device, all must be connected to the appropriate levels in order for the debugger to
operate.
In general, it is recommended that all V
the appropriate levels. Also, devices with a V
be connected to the appropriate capacitor or level.
Note:
DS51766A-page 16
STANDARD CONNECTION TARGET CIRCUITRY
Application
PC Board
V
DD
Device
4.7K-10K
V /MCLR
PP
PGC
PGD
V
SS
AV
DD
AV
SS
Target Powered
/MCLR), 5 (PGC) and 4 (PGD). Pins 2 (V
PP
is sensed by the debugger to allow level translation for
DD
Debugger Powered
is sensed by the debugger to allow level translation for
DD
and AV
DD
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 ICD 3 in-circuit debugger system,
as discussed in the following section.
User Reset
2
1
5
4
3
Interface
Connector
DD
DD
lines, but if they are present on the target
SS
/AV and V /AV lines be connected to
DD DD SS SS
line (PIC18FXXJ for example) should
CAP
© 2008 Microchip Technology Inc.
) and 3 (V ) are
SS
line
DD
separated from the
line (pin
DD