LT3782EFE-PBF LINER [Linear Technology], LT3782EFE-PBF Datasheet - Page 15

• Manufacturer Part Number: LT3782EFE-PBF
• Description: 2-Phase Step-UP DC/DC Controller
• Manufacturer: LINER [Linear Technology]

APPLICATIONS INFORMATION
2. Power MOSFET switching and conduction losses:
3. The I
4. The losses in the inductor are simply the DC input cur-
almost by inspection.
rent squared times the winding resistance. Expressing
this loss as a function of the output current yields:
P
P
P
FET
R(SENSE)
R(WINDING)
2
R losses in the sense resistor can be calculated
+ k • V
=
1– D
I
O(MAX)
=
O
2
2
=
MAX
1– D
I
•
O(MAX)
1– D
1– D
I
I
O(MAX)
O(MAX)
2
MAX
2
2
2
• R
MAX
MAX
DS(ON)
2
• C
• R • D
2
• R
RSS
• D
W
MAX
• f
MAX
•
T
5. Losses in the boost diode. The power dissipation in the
6. Other losses, including C
PCB Layout Considerations
To achieve best performance from an LT3782 circuit, the
PC board layout must be carefully done. For lower power
applications, a two-layer PC board is suffi cient. However,
at higher power levels, a multiplayer PC board is recom-
mended. Using a solid ground plane under the circuit is
the easiest way to ensure that switching noise does not
affect the operation.
In order to help dissipate the power from MOSFETs and
diodes, keep the ground plane on the layers closest to the
layers where power components are mounted. Use power
planes for MOSFETs and diodes in order to improve the
spreading of the heat from these components into the
PCB.
boost diode is:
The boost diode can be a major source of power loss
in a boost converter. For 13.2V input, 42V output at 3A,
a Schottky diode with a 0.4V forward voltage would
dissipate 600mW, which represents about 1% of the
input power. Diode losses can become signifi cant at
low output voltages where the forward voltage is a
signifi cant percentage of the output voltage.
inductor core losses, generally account for less than
2% of the total losses.
P
DIODE
=
I
O(MAX)
2
• V
D
IN
and C
O
ESR dissipation and
LT3782
15
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