Vicor Constant Current (CC) Demonstration Board - Manual (Page 8)

UG:007 vicorpower.com Applications Engineering: 800 927.9474 Page 8
The CC sense resistor (R33) is located right before the output voltage oscilloscope probe jack
(J02). Probing the input pins while connecting a probe to (J02) will introduce another low
resistance return path. The amount of current circulating through that path is difficult to
predict. The current through the added path will not be sensed by the CC circuit. The CC
circuit will require the PRM to compensate for this loss. The current through the load will be
equal to the user set reference current and the unknown variable current through the scope.
In short, this may damage the load and equipment used due to excess current.
3.0 Test Procedure
3.1 Recommended Equipment
• DC power supply – 0-100 V; 500 W
• DC electronic load – pulse capable; 0-100 V; 100 A minimum
• Two digital multi-meters (DMMs)
• Oscilloscope
• Fan (if the PRM-VTM to be operated for extended periods of time or at an elevated
ambient temperature we recommend the supplied heat sink be installed)
• Safety glasses
• datasheet for the requisite PRM / VTM
3.2 Prerequisites
• Maximum desired output voltage.
• Desired PRM output current.
3.3 Initial CC Demonstration Board Set Up (V
REF
and V
MAX
Set)
Figure 8
CC No Load Functional
Verification
DC
+ +
- -
CCBD-CC
+
-
Electronic Load
+OUT
DMM
Measuring
Output Current
Set to Constant Current mode
DMM
Measuring Voltage V REF
using test point TP5
–OUT
+IN
–IN
1. Have the latest PRM datasheet in hand.
2. Install heat sink if desired.
3. Assure that the DC supply is set to 0.0 Vdc prior to turning the unit on.
4. Set the supply current limit to a higher value than the chosen PRM DC current limit.
5. Set the DC load to 0.0 A, constant current mode.