EN23F0QI-E Enpirion, EN23F0QI-E Datasheet - Page 21

• Manufacturer Part Number: EN23F0QI-E
• Description: Power Management IC Development Tools EVAL FOR EN23F0QI
• Manufacturer: Enpirion
• Type: DC/DC Converters, Regulators & Controllersr

Specifications of EN23F0QI-E

• Rohs: yes
• Product: Evaluation Boards
• Tool Is For Evaluation Of: EN23F0QI
• Input Voltage: 4.5 V to 14 V
• Output Voltage: 0.6 V to 5 V
• Output Current: 6 A

Thermal Considerations
Thermal considerations are important power supply
design facts that cannot be avoided in the real
world. Whenever there are power losses in a
system, the heat that is generated by the power
dissipation needs to be accounted for. The Enpirion
PowerSoC helps alleviate some of those concerns.
The Enpirion EN23F0QI DC-DC converter is
packaged in an 8x11x3mm 68-pin QFN package.
The QFN package is constructed with copper lead
frames that have exposed thermal pads. The
exposed thermal pad on the package should be
soldered directly on to a copper ground pad on the
printed circuit board (PCB) to act as a heat sink.
The recommended maximum junction temperature
for continuous operation is 125°C. Continuous
operation above 125°C may reduce long-term
reliability. The device has a thermal overload
protection circuit designed to turn off the device at
an approximate junction temperature value of
150°C.
The EN23F0QI is guaranteed to support the full 4A
output current up to 85°C ambient temperature.
The following example and calculations illustrate
the thermal performance of the EN23F0QI.
Example:
V
V
I
First calculate the output power.
P
Next, determine the input power based on the
efficiency (η) shown in Figure 11.
©Enpirion 2012 all rights reserved, E&OE
OUT
IN
OUT
OUT
= 12V
= 15A
100
= 1.2V x 15A = 18W
= 1.2V
90
80
70
60
50
40
30
20
10
0
Figure 11: Efficiency vs. Output Current
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Efficiency vs. Output Current
OUTPUT CURRENT (A)
VOUT = 3.3V
VOUT = 1.8V
VOUT = 1.2V
CONDITIONS
V
AVIN = 3.3V
Dual Supply
IN
= 12.0V
Enpirion Confidential
For V
η = P
P
P
The power dissipation (P
system and can be calculated by subtracting the
output power from the input power.
P
With the power dissipation known, the temperature
rise in the device may be estimated based on the
theta JA value (θ
how much the temperature will rise in the device for
every watt of power dissipation. The EN23F0QI has
a θ
Determine the change in temperature (ΔT) based
on P
ΔT = P
ΔT ≈ 4.5W x 13°C/W = 58.5°C ≈ 59°C
The junction temperature (T
approximately the ambient temperature (T
the change in temperature. We assume the initial
ambient temperature to be 25°C.
T
T
The maximum operating junction temperature
(T
operate at a higher ambient temperature. The
maximum ambient temperature (T
be calculated.
T
The maximum ambient temperature the device can
reach is 66°C given the input and output conditions.
Note that the efficiency will be slightly lower at
higher temperatures and this calculation is an
estimate.
J
J
AMAX
IN
IN
D
JMAX
= T
≈ 25°C + 59°C ≈ 84°C
= P
≈ 22.5W – 18W ≈ 4.5W
JA
= P
≈ 18W / 0.8 ≈ 22.5W
D
OUT
value of 13 ºC/W without airflow.
IN
) of the device is 125°C, so the device can
A
= T
and θ
≈ 125°C – 59°C ≈ 66°C
IN
D
OUT
= 12V, V
+ ΔT
x θ
– P
/ P
JMAX
/ η
JA
IN
OUT
JA
= 80% = 0.8
.
– P
OUT
D
JA
x θ
= 1.2V at 15A, η ≈ 80%
). The θ
JA
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D
) is the power loss in the
JA
parameter estimates
J
) of the device is
AMAX
EN23F0QI
) allowed can
A
) plus