The maximum power dissipation at TA = 25°C can be
calculated by following formula :
PD(MAX) = (125°C − 25°C) / 45°C/W = 2.22W for SOP-8
package
100
90
80
70
60
50
40
30
20
10
0
0
20
40
60
80
100
Copper Area (mm2)
Figure 1
The maximum power dissipation depends on operating
ambient temperature for fixed TJ(MAX) and thermal resistance
θJA . For RT9027AB packages, the Figure 2 of de-rating
curves allows the designer to see the effect of rising
ambient temperature on the maximum power allowed.
2.4
2.2
2 50mm2
100mm2
JEDEC 4-layers PCB
1.8
1.6 25mm2
1.4 15mm2
1.2
1 min. layout
0.8
0.6
0.4
0.2
0
0
25
50
75
100
125
Ambiemt Temperature (℃°C)
Figure 2. De-rating Curves for RT9027AB Package
DS9027A/B-01 October 2008
Downloaded from Elcodis.com electronic components distributor
RT9027A/B
www.richtek.com
11
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