LTM4613 datasheet(19/28 Pages) LINER

19 / 28 page

LTM4648

4648f

For more information www.linear.com/LTM4648

applicaTions inForMaTion

Figure 9. 3.3VIN to 2.5VOUT and 1.5VOUT Power Loss

Figure 10. 5VIN to 3.3VOUT, 2.5VOUT and 1.5VOUT Power Loss

resistance values supplied in this data sheet: (1) Initially,

FEA software is used to accurately build the mechanical

geometry of the µModule and the specified PCB with all

of the correct material coefficients along with accurate

power loss source definitions; (2) this model simulates

a software-defined JEDEC environment consistent with

JESD51-9 to predict power loss heat flow and temperature

readingsatdifferentinterfacesthatenablethecalculationof

theJEDEC-definedthermalresistancevalues;(3)themodel

and FEA software is used to evaluate the µModule with

heat sink and airflow; (4) having solved for and analyzed

these thermal resistance values and simulated various

operating conditions in the software model, a thorough

laboratory evaluation replicates the simulated conditions

with thermocouples within a controlled-environment

chamber while operating the device at the same power

loss as that which was simulated. An outcome of this

process and due-diligence yields a set of derating curves

provided in other sections of this data sheet. After these

laboratory test have been performed and correlated to the

µModulemodel,thentheθJBandθBAaresummedtogether

to correlate quite well with the µModule model with no

airflow or heat sinking in a properly define chamber. This

θJB + θBA value is shown in the Pin Configuration section

and should accurately equal the θJA value because ap-

proximately 100% of power loss flows from the junction

through the board into ambient with no airflow or top

mounted heat sink.

The 1.5V, 2.5V and 3.3V power loss curves in Figures 9

and 10 can be used in coordination with the load current

derating curves in Figures 11 to 15 for calculating an

approximate θJA thermal resistance for the LTM4648 with

variousheatsinkingandairflowconditions. Thepowerloss

curves are taken at room temperature, and are increased

with a multiplicative factor according to the ambient

temperature. This approximate factor is: 1.4 for 120°C.

The derating curves are plotted with the output current

starting at 10A and the ambient temperature at 40°C. The

output voltages are 1.5V, 2.5V and 3.3V. These are chosen

to include the lower and higher output voltage ranges for

correlating the thermal resistance. Thermal models are

derived from several temperature measurements in a

controlled temperature chamber along with thermal mod-

eling analysis. The junction temperatures are monitored

while ambient temperature is increased with and without

airflow.Thepowerlossincreasewithambienttemperature

change is factored into the derating curves. The junctions

LOAD CURRENT (A)

0.6

0.8

1.0

4648 F09

0.4

0.2

1.2

1.4

1.6

1.5VOUT

2.5VOUT

LOAD CURRENT (A)

1.2

1.6

2.0

4648 F10

0.8

0.4

1.0

1.4

1.8

0.6

0.2

1.5VOUT

2.5VOUT

3.3VOUT

LTM4613 Datasheet(PDF) 19 Page - Linear Technology

LTM4613 Datasheet(HTML) 19 Page - Linear Technology

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Datasheet Download

Link URL