Texas Instruments Evaluation Module for TPS72715 TPS72715YFFEVM-407 TPS72715YFFEVM-407 Datenbogen
Produktcode
TPS72715YFFEVM-407
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Thermal Guidelines
The measured thermal resistance from junction to ambient for the TPS727xxEVM has a typically value of
224
224
˚
C/W. The recommended maximum operating junction temperature specified in the datasheet for the
TPS727xx family is 125°C. With these two pieces of information, the maximum power dissipation can be
found by using
found by using
Example Calculation:
For example, what is the maximum input voltage that can be applied to a TPS727xx with a 1.5V output
voltage if the ambient temperature is 85C and the full 200mA of load current is required?
voltage if the ambient temperature is 85C and the full 200mA of load current is required?
Given: T
J
= 125°C, T
A
= 85°C,
q
JA
= 224°C/W
(2)
Using
, we substitute in the given values above and find that the maximum power dissipation
for the part is P
d
=0.178W.
125°C = 85°C + P
d
(224°C/W)
(3)
This means that the total power dissipation of the TPS727xx must be less than 0.178W. Now the input
voltage can be calculated.
voltage can be calculated.
P
d
= (V
in
–V
out
) × I
out
= (Vin – 1.5V) × 0.2A = 0.178W
(4)
So the maximum input voltage would need to be 2.39V or less in order to maintain a safe junction
temperature.
temperature.
Similar analysis can be performed to determine the maximum input voltage at room temperature (25°C) or
85°C to provide full output current while maintaining the junction temperature at or below 125°C. The
answer will depend on the output voltage.
85°C to provide full output current while maintaining the junction temperature at or below 125°C. The
answer will depend on the output voltage.
Maximum Input Voltage vs VOUT and
Temperature
VOUT
25°C
85°C
1.5
3.73
2.39
1.8
4.03
2.69
2.8
5.03
3.69
3
SLVU323 – February 2010
TPS727xxYFF EVM
Copyright © 2010, Texas Instruments Incorporated