Preliminary
RT9013
Where TJ(MAX) is the maximum operation junction
temperature, TA is the ambient temperature and the θJA is
the junction to ambient thermal resistance.
For recommended operating conditions specification of
RT9013, where TJ(MAX) is the maximum junction
temperature of the die (125°C) and TA is the operated
ambient temperature. The junction to ambient thermal
resistance θJA (θJA is layout dependent) for WDFN-6L 2x2
package is 165°C/W, SOT-23-5 package is 250°C/W and
SC-70-5 package is 333°C/W on the standard
JEDEC 51-3 single-layer thermal test board. The maximum
power dissipation at TA = 25°C can be calculated by
following formula :
PD(MAX) = (125°C − 25°C) / 165 = 0.606 W for
WDFN-6L 2x2 packages
PD(MAX) = (125°C − 25°C) / 250 = 0.400 W for SOT-23-5
packages
PD(MAX) = (125°C − 25°C) / 333 = 0.300 W for SC-70-5
packages
The maximum power dissipation depends on operating
ambient temperature for fixedTJ(MAX) and thermal resistance
θJA. For RT9013 packages, the Figure 2 of derating curves
allows the designer to see the effect of rising ambient
temperature on the maximum power allowed.
0.7
Single Layer PCB
0.6
0.5
WDFN-6L 2x2
SOT-23-5
SC-70-5
0.4
0.3
0.2
0.1
0
0
12.5 25 37.5 50 62.5 75 87.5 100 113 125
Ambient Temperature
(°C)
Figure 2.Derating Curves for RT9013 Packages
DS9013-05 August 2007
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