Functional Description (Continued)
Keep the gap of exposed pads from short circuit.
Top Side Layout Guide
AP1539
18V 4A 300KHz BUCK CONVERTER
Recommended exposed-pads gap: 30~40mil
(0.75~1mm)
Use vias to conduct the heat into the backside of
PCB layer. The heat sink at output (SW) pins should
be allowed for maximum solder-painted area.
Bottom Side Layout Guide
Brown: IC exposed pads.
Red: recommended layout.
Reference pads layout dimension:
Output: 90 x 50 mil
Vss: 90 x 60 mil
AP1539 Rev. 4
DS31477
10 of 13
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OCTOBER 2009
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