RT2528
The maximum power dissipation depends on the operating
ambient temperature for fixed TJ(MAX) and thermal
resistance, θJA. The derating curve in Figure 2 allows the
designer to see the effect of rising ambient temperature
on the maximum power dissipation.
Layout Consideration
Ounce copper on top layer will improve thermal
performance. 4-layer PCB will be better.
Place the shape with minimum 70mm2 as Figure 3
around the SOP-8 (Exposed Pad) footprint to achieve
best thermal performance.
3.0
Four-Layer PCB
2.5
2.0
1.5
1.0
0.5
0.0
Copper Area = 70mm2, θJA = 49°C/W
Figure 3. PCB CopperArea
0
25
50
75
100
125
Utilize standard PTH (Plated Through Hole, 25mil
diameter, as Figure 4) to Via down from exposed pad
on top layer to GND plane on other layers.
Ambient Temperature (°C)
Figure 2. Derating Curve of Maximum PowerDissipation
Figure 4. Standard PTH toGNDPlane
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is a registered trademark of Richtek Technology Corporation.
DS2528-03 November 2013
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