Package Description
5-4
TSEV83102G0B - Evaluation Board User Guide
2166B–BDC–04/03
5.2.2
Thermal Resistance
from Junction to
Case: Rthjc
Maximum thermal Junction to Case resistance is 4.0
°
C/Watt.
This value does not include thermal contact resistance between the package and exter-
nal heatsink (glue, paste, or thermal foil interface for example).
As an example, we can take 2.0
°
C/W for 50 µm thickness of thermal grease.
5.2.3
Heatsink
It is recommended to use a 50 mm x 50 mm x 30 mm heatsink (respectively L x l x H) in
case of natural convection cooling mode (with no air flow).
A fan heatsink or direct conduction cooling is recommended, due to high power dissipa-
tion (4.7W).
A method should be chosen for cooling that allows less than 4.0
°
C/W for the case to
ambient thermal resistance (Rthca).
The thermal resistance of the board is a high value (within a range of 30
°
C/W); thus an
external heatsink is mandatory.
The heatsink must be fixed to the heatspreader which is at -5V. So the heatsink needs
to be electrically isolated; using adequate low Rth electrical isolation.
Example: 4.0
°
C/W Rthca (case to ambient) +2.0
°
C/W thermal grease resistance
+4.0
°
C/W Rthjc = 10.0
°
C/W total (Rthja).
The heatsink should make contact with the package on the side opposite to the balls, in
a 8.5 mm diameter circle:
Figure 5-3. CBGA152 Board Assembly
Cooling system efficiency can be monitored using the Temperature Sensing Diodes,
integrated in the device.
31
8.5
32.5
Board
50.5
20.2
24.2
Note: The measures are given in mm.
