LTM4606IV-PBF View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTM4606IV-PBF' PDF : 24 Pages View PDF
LTM4606
APPLICATIONS INFORMATION
Thermal Considerations and Output Current Derating
In different applications, LTM4606 operates in a variety
of thermal environments. The maximum output current is
limited by the environment thermal condition. Sufficient
cooling should be provided to help ensure reliable opera-
tion. When the cooling is limited, proper output current
derating is necessary, considering ambient temperature,
airflow, input/output condition, and the need for increased
reliability.
The power loss curves in Figures 6 and 7 can be used
in coordination with the load current derating curves in
Figures 8 to 15 for calculating an approximate θJA for the
module. The graphs delineate between no heat sink, and
a BGA heat sink. Each of the load current derating curves
will lower the maximum load current as a function of the
increased ambient temperature to keep the maximum junc-
tion temperature of the power module at 125°C maximum.
Each of the derating curves and the power loss curve that
corresponds to the correct output voltage can be used to
solve for the approximate θJA of the condition. Each figure
has three curves that are taken at three different air flow
conditions. Tables 3 and 4 provide the approximate θJA
for Figures 8 to 15. A complete explanation of the thermal
characteristics is provided in the thermal application note
AN110.
Safety Considerations
The LTM4606 modules do not provide isolation from VIN to
VOUT. There is no internal fuse. If required, a slow blow fuse
2.5
2.0
12V LOSS
1.5
5V LOSS
1.0
0.5
0
01
2 34 5
OUTPUT CURRENT (A)
67
4606 F06
Figure 6. 1.5V Power Loss
4.0
3.5
3.0
24V LOSS
2.5
2.0
1.5
12V LOSS
1.0
0.5
0
01
2 34 5
OUTPUT CURRENT (A)
67
4606 F07
Figure 7. 3.3V Power Loss
6
5
4
3
2
1
5VIN, 1.5VOUT, 0LFM
5VIN, 1.5VOUT, 200LFM
5VIN, 1.5VOUT, 400LFM
0
75
80
85
90
95
AMBIENT TEMPERATURE (°C)
4606 F08
Figure 8. No Heat Sink
6
6
6
5
5
5
4
4
4
3
3
3
2
1
5VIN, 1.5VOUT, 0LFM
5VIN, 1.5VOUT, 200LFM
5VIN, 1.5VOUT, 400LFM
0
75
80
85
90
95
AMBIENT TEMPERATURE (°C)
4606 F09
Figure 9. BGA Heat Sink
14
2
1
0
70 75
80
85
90
95
AMBIENT TEMPERATURE (°C)
12VIN, 1.5VOUT, 0LFM
12VIN, 1.5VOUT, 200LFM
12VIN, 1.5VOUT, 400LFM
4606 F10
Figure 10. No Heat Sink
2
1
12VIN, 1.5VOUT, 0LFM
12VIN, 1.5VOUT, 200LFM
12VIN, 1.5VOUT, 400LFM
0
70 75
80
85
90
95
AMBIENT TEMPERATURE (°C)
4606 F11
Figure 11. BGA Heat Sink
4606f
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