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Thermal Guidelines www.ti.com
Figure 5. TPS7A8101 Transient Response
4 Thermal Guidelines
This section provides guidelines for the thermal management of the TPS7A81xxDRBEVM board.
4.1 Thermal Considerations
Thermal management is a key design component of any power converter and is especially important
when the power dissipation in the LDO is high. To better help you design the TPS7A81xxDRB family into
your application, use Equation 1 to approximate the maximum power dissipation at a particular ambient
temperature:
T
J
= T
A
+ P
d
× θ
JA
(1)
where T
J
is the junction temperature, T
A
is the ambient temperature, P
d
is the power dissipation in the
integrated circuit (IC) and θ
JA
is the thermal resistance from junction to ambient. All temperatures are in
degrees Celsius.
The measured thermal resistance from junction to ambient for the TPS7A8101EVM has a typical value of
45.7°C/W. The recommended maximum operating junction temperature specified in the data sheet for the
TPS7A8101 is 125°C. With this information, the maximum power dissipation can be found by using
Equation 1.
Table 1 shows the maximum input voltage that can be applied to the input of the TPS7A8101EVM and still
provide the full 1 A of output current. Table 1 shows the input voltage versus the output voltage setting
and two ambient temperatures (25°C and 85°C). The maximum input voltage shown provides the rated
output current while keeping the junction temperature at or below the recommended 125°C.
Table 1. Maximum Input Voltage vs Ambient Temperature and Output Voltage
Selected Output Voltage (V)
Ambient Temp Iout (A) 1.8 2.5 2.8 3.3
25 1.00 3.98 4.68 4.98 5.48
6
TPS7A8101EVM Evaluation Module SLVU600– December 2011
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