LTM4642

21

4642fb

applicaTions inForMaTion

process and due diligence yields a set of derating curves

provided in other sections of this data sheet. After these

LTM4642modelwithnoairfloworheatsinkinginaproperly

value because approximately 100% of power loss flows

from the junction through the board into ambient with no

airflow or top mounted heat sink. Each system has its own

thermal characteristics, therefore thermal analysis must

be performed by the user in a particular system.

The LTM4642 has been designed to effectively remove

heat from both the top and bottom of the package. The

bottom substrate material has very low thermal resistance

to the printed circuit board and the exposed top metal is

thermally connected to the power devices and the power

inductors. An external heat sink can be applied to the top of

the device for excellent heat sinking with airflow. Basically

all power dissipating devices are mounted directly to the

substrate and the top exposed metal. This provides two

low thermal resistance paths to remove heat.

Safety Considerations

The LTM4642 modules do not provide galvanic isolation

a slow blow fuse with a rating twice the maximum input

current needs to be provided to protect each unit from

catastrophic failure.

PHASE (A)

HOT TEMP

PEAK TEMP (°C)

12

2.5

1.5

4

1000

56.6

Figure 7. Thermal Plot for the Specified Operation. The Temperature Rise About 25°C Ambient Is About 30°C Rise