LTM4614IV#PBF Linear Technology, LTM4614IV#PBF Datasheet - Page 12

• Manufacturer Part Number: LTM4614IV#PBF
• Description: IC UMODULE DC/DC DUAL 4A 144LGA
• Manufacturer: Linear Technology
• Series: µModuler
• Type: Point of Load (POL) Non-Isolatedr

Specifications of LTM4614IV#PBF

• Design Resources: LTM4614 Spice Model
• Output: 0.8 ~ 5 V
• Number Of Outputs: 2
• Power (watts): 12W
• Mounting Type: Surface Mount
• Voltage - Input: 2.38 ~ 5.5 V
• Package / Case: 144-LGA
• 1st Output: 0.8 ~ 5 VDC @ 4A
• 2nd Output: 0.8 ~ 5 VDC @ 4A
• Size / Dimension: 0.59" L x 0.59" W x 0.11" H (15mm x 15mm x 2.8mm)
• Power (watts) - Rated: 12W
• Operating Temperature: -40°C ~ 125°C
• Efficiency: 95%
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• 3rd Output: -

LTM4614
APPLICATIONS INFORMATION
Parallel Switching Regulator Operation
The LTM4614 switching regulators are inherently current
mode control. Paralleling will have very good current
sharing. This will balance the thermals on the design.
Figure 13 shows a schematic of a parallel design. The
voltage feedback equation changes with the variable N
as channels are paralleled.
The equation:
N is the number of paralleled channels.
Thermal Considerations and Output Current Derating
The power loss curves in Figures 5 and 6 can be used
in coordination with the load current de-rating curves in
Figures 7 to 10 for calculating an approximate θ
resistance for the LTM4614 with various heat sinking
12
V
OUT
= 0.8V •
2.5
2.0
1.5
1.0
0.5
0
0
Figure 5. 1.2V Power Loss
4.99k
N
1
R
LOAD CURRENT (A)
FB
+ R
FB
2
3
V
IN
= 5V
4614 F05
4
JA
thermal
and airfl ow conditions. Both of the LTM4614 outputs
are at full 4A load current, and the power loss curves in
Figures 5 and 6 are combine power losses plotted for both
output voltages up to 4A each. The 4A output voltages are
1.2V and 3.3V. These voltages 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 tem-
perature chamber along with thermal modeling analysis.
The junction temperatures are monitored while ambient
temperature is increased with and without airfl ow. The
junctions are maintained at ~120°C while lowering output
current or power while increasing ambient temperature.
The 120°C is chosen to allow for a 5°C margin window
relative to the maximum 125°C. The decreased output
current will decrease the internal module loss as ambi-
ent temperature is increased. The power loss curves in
Figures 5 and 6 show this amount of power loss as a
function of load current that is specifi ed for both chan-
nels The monitored junction temperature of 120°C minus
the ambient operating temperature specifi es how much
3.0
2.5
2.0
1.5
1.0
0.5
0
0
Figure 6. 3.3V Power Loss
1
LOAD CURRENT (A)
2
3
V
IN
= 5V
4614 F06
4
4614fa