RT9054 Datasheet, PDF (10/11 Pages) Richtek Technology Corporation – Portable Power Management 300mA Dual LDO Regulator

RT9054
For recommended operating conditions specification of
the IC, the maximum junction temperature is 125°C. The
junction to ambient thermal resistance ( θ_JA is layout
dependent ) for WDFN-8L 1.6x1.6 is 175°C/W on the
standard JEDEC 51-3 single-layer thermal test board. The
maximum power dissipation at T_A = 25°C can be calculated
by the following formula :
P_D(MAX) = ( 125°C − 25°C ) / (175°C/W) = 0.571W for
WDFN-6L 1.6x1.6 packages
The maximum power dissipation depends on the operating
ambient temperature for fixed T_J(MAX) and thermal
resistance θ_JA. For the IC packages, the Figure 3 of de-
rating curves allows the designer to see the effect of rising
ambient temperature on the maximum power dissipation.
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
Single Layer PCB
WDFN-6L 1.6x1.6
25
50
75
100
125
Ambient Temperature (°C)
Figure 3. Derating Curve of Maximum Power Dissipation
Copyright ©2012 Richtek Technology Corporation. All rights reserved.
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10
is a registered trademark of Richtek Technology Corporation.
DS9054-03 February 2012