Vicor VI Chip High Voltage BCM Bus Converter 6123 Evaluation Board - Manual (Page 7)

UG:015 vicorpower.com Applications Engineering: 800 927.9474 Page 7
Thermal Considerations
A fan blowing across the evaluation board and heat sink assembly is required during
operation. It is recommended to use a typical (4 x 4) inches fan (similar to an EBM-
PAPST 3212). It is recommended to place the evaluation board using the supplied
rubber feet about 0.4 inches off a flat surface. As per the example below, the board was
tested using a fan about 4 inches from the board. The maximum internal temperatures
of the BCM® at full rated power should remain below 80°C at 25°C ambient air.
Top airflow was measured above the edge of the midpoint of the output side of the PCB,
over the oscilloscope probe terminal. Bottom airflow was measured under the edge of
the midpoint of the output side of the PCB.
IR images were taken while evaluating several fans to guarantee full power operation
within data sheet thermal specification. Figure 6 shows one case where an off-the-shelf
fan “EBM-PAPSTJH3” was set to 12 V
IN
. The measured top airflow is 1,500 LFM and
bottom is 2,250 LFM. The internal temperature is estimated to be 66°C. Figure 7 shows
a top surface IR image max of 40°C. Figure 8 shows another case using the same fan
where V
IN
is set 6 V. In this case, the measured top airflow is 1,000 LFM and bottom is
1,750 LFM. The internal temperature is estimated to be 64°C. Figure 8 a top IR image
max of 44°C.
Figure 4.
Double Side Cooling and Leads
Thermal Model
Figure 5.
Example Setup
+
–
+
–
+
–
MAX INTERNAL TEMP
1.24°C / W
1.33°C / W 7°C / W
T
CASE_BOTTOM
(°C) T
CASE_LEADS
(°C) T
CASE_TOP
(°C) Power Dissipation (W)
Thermal Resistance Top
Thermal Resistance Bottom Thermal Resistance Leads