DETAILED DESCRIPTION
Maximum power dissipation of the package may
limit output current or input voltage, which can be
used. The power dissipation can be calculated by
using the formula:
( ) Pd = VIN − VOUT * IOUT + VIN * IGND
It shall not exceed the maximum power dissipation,
allowed by the package:
PdMAX
=
TJ(MAX) − TA
R JA
where TJmax is maximum junction temperature
(TJmax = 125°C), TA is ambient temperature and RJA
is junction-to-ambient thermal resistance of the
package.
When assumed that:
TA = + 85 °C
VOUT = 2.5 V
VIN = 5.3 V
the equation results:
PdMAX
=
125°C − 85°C
255.9°C/W
=
0.156
W
from which can be calculated:
IOUTMAX
=
PdMAX
VIN − VOUT
= 55 mA
VIN * IGND is negligible and can be omitted.
So it can be seen that under these conditions the
average output current should not exceed 55 mA.
If higher power dissipation capability is needed,
contact Micro Analog Systems for TSOT 5
packaging option, see Ordering Information p. 10.
DA9162.003
13 March 2003
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