LTM8029 LINER [Linear Technology], LTM8029 Datasheet - Page 16

• Manufacturer Part Number: LTM8029
• Description: 36VIN, 600mA Step-Down ?Module Converter
• Manufacturer: LINER [Linear Technology]

LTM8029
applicaTions inForMaTion
Given these definitions, it should now be apparent that none
of these thermal coefficients reflects an actual physical
operating condition of a µModule converter. Thus, none
of them can be individually used to accurately predict the
thermal performance of the product. Likewise, it would
be inappropriate to attempt to use any one coefficient to
correlate to the junction temperature vs load graphs given
in the product’s data sheet. The only appropriate way to
use the coefficients is when running a detailed thermal
analysis, such as FEA, which considers all of the thermal
resistances simultaneously.
A graphical representation of these thermal resistances
is given in Figure 4.
16
JUNCTION
µMODULE DEVICE
Figure 4. Graphical Representation of JESD 51-12 Thermal Coefficients
(BOTTOM) RESISTANCE
JUNCTION-TO-CASE
JUNCTION-TO-AMBIENT RESISTANCE (JESD 51-9 DEFINED BOARD)
JUNCTION-TO-BOARD RESISTANCE
JUNCTION-TO-CASE (TOP)
RESISTANCE
CASE (BOTTOM)-TO-BOARD
RESISTANCE
The blue resistances are contained within the µModule
converter, and the green are outside.
The die temperature of the LTM8029 must be lower than
the maximum rating of 125°C, so care should be taken in
the layout of the circuit to ensure good heat sinking of the
LTM8029. The bulk of the heat flow out of the LTM8029
is through the bottom of the μModule converter and the
BGA pads into the printed circuit board. Consequently a
poor printed circuit board design can cause excessive
heating, resulting in impaired performance or reliability.
Please refer to the PCB Layout section for printed circuit
board design suggestions.
CASE (TOP)-TO-AMBIENT
BOARD-TO-AMBIENT
RESISTANCE
RESISTANCE
8029 F04
AMBIENT
8029f