Texas Instruments TLV70018EVM-503 Evaluation Module TLV70018EVM-503 TLV70018EVM-503 데이터 시트
제품 코드
TLV70018EVM-503
J
A
d
JA
T
T
P
=
+
´ q
J
JA
T
125 C, TA
85 C,
200 C / W
=
°
=
°
q
=
°
(
)
d
125 C
85 C
P
200 C / W
°
=
°
+
°
(
)
(
)
d
IN
OUT
OUT
IN
P
V
V
I
V
2.5
0.2 A
0.2 W
=
-
´
=
-
´
=
Thermal Guidelines
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4
Thermal Guidelines
This section provides guidelines for the thermal management of the TLV700xxEVM-503 board.
4.1
Thermal Considerations
Thermal management is a key component of design of any power converter and is especially important
when the power dissipation in the LDO is high. To better help you design the TLV700xx family into your
application, use the following formula to approximate the maximum power dissipation at a particular
ambient temperature:
when the power dissipation in the LDO is high. To better help you design the TLV700xx family into your
application, use the following formula to approximate the maximum power dissipation at a particular
ambient temperature:
(1)
where T
J
is the junction temperature, T
A
is the ambient temperature, P
d
is the power dissipation in the
device, and
θ
JA
is the thermal resistance from junction to ambient. All temperatures are in degrees
Celsius.
The thermal resistance from junction to ambient for the TLV700xxEVM has a typically value of 200°C/W.
The recommended maximum operating junction temperature specified in the data sheet for the TLV700xx
family is 125°C. With these two pieces of information, the maximum power dissipation can be found by
using
The recommended maximum operating junction temperature specified in the data sheet for the TLV700xx
family is 125°C. With these two pieces of information, the maximum power dissipation can be found by
using
Example Calculation:
For example, what is the maximum input voltage that can be applied to a TLV70025 (fixed 2.5-V output) if
the ambient temperature is 85°C and the full 200 mA of load current is required?
the ambient temperature is 85°C and the full 200 mA of load current is required?
(2)
Using
, substitute in the preceding given values and find that the maximum power dissipation
for the part is P
d
= 0.2 W.
(3)
This means that the total power dissipation of the TLV70025 must be less than 0.2 W. Now, the input
voltage can be calculated.
voltage can be calculated.
(4)
So, the maximum input voltage needs to be 3.5 V or less in order to maintain a safe junction temperature.
Similar analysis can be performed to determine the maximum ambient temperature over a range of
operation. For an input voltage of 3.3 V you can calculate the highest ambient temperature allowed and
still provide full output current.
operation. For an input voltage of 3.3 V you can calculate the highest ambient temperature allowed and
still provide full output current.
Using
and
again, T
A
is 93.0°C.
4
TLV700xxEVM-503
SLUU391 – December 2009
Copyright © 2009, Texas Instruments Incorporated