RT9011_11 Datasheet, PDF (10/15 Pages) Richtek Technology Corporation – Portable Power Management 300mA Dual LDO Regulator

RT9011
For recommended operating conditions specification of
RT9011, the maximum junction temperature is 125°C. The
junction to ambient thermal resistance ( θ_JA is layout
dependent ) for TSOT-23-6 is 220°C/W, WDFN-8L 2x2 is
165°C/W, WDFN-10L 3x3 is 108°C/W, WDFN-8L 3x3 is
108°C/W and 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 following formula :
P_D(MAX) = ( 125°C − 25°C ) / (220°C/W) = 0.455W for
TSOT-23-6 packages
P_D(MAX) = ( 125°C − 25°C ) / (165°C/W) = 0.606W for
WDFN-8L 2x2 packages
P_D(MAX) = ( 125°C − 25°C ) / (108°C/W) = 0.926W for
WDFN-10L 3x3 packages
P_D(MAX) = ( 125°C − 25°C ) / (108°C/W) = 0.926W for
WDFN-8L 3x3 packages
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 operating
ambient temperature for fixed T_J(MAX) and thermal
resistance θ_JA. For RT9011 packages, the Figure 3 of de-
rating curves allows the designer to see the effect of rising
ambient temperature on the maximum power allowed.
1
0.9
0.8
0.7
WDFN-8L 2x2
0.6
Single Layer PCB
WDFN-8L 3x3
WDFN-10L 3x3
0.5
0.4 TSOT-23-6
0.3
0.2
WDFN-6L 1.6x1.6
0.1
0
0
25
50
75
100
125
Ambient Temperature (°C)
Figure 3. Derating Curves for RT9011 Packages
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10
DS9011-08 April 2011