Figure 12-1 shows the TPS65981 footprint with 56 0.6-mm long by 0.25-mm wide rectangular pads and 1 5.9-mm by 5.9-mm square, grounded Thermal Pad. This footprint is applicable to boards that will be using a non-HDI process using all through-hole vias or an HDI PCB process using smaller vias to fan-out into the inner layers of the PCB. Via fills and via tenting is recommended for size-constrained applications. The footprint allows for easy fan-out into other layers of the PCB and thermal dissipation into the GND plane(s) from vias placed directly under the large, square grounded Thermal Pad. Figure 12-2 shows the minimum recommended via sizing for use under the thermal pad. The size is 8-mil hole and 16-mil diameter. This via size will allow for approximately 1.8-A of DC current rating at 1.5 mΩ of resistance with 1.3 nH of inductance. Some board manufacturers can guarantee vias with a 6-mile hole and 12-mil diameter using a standard mechanical drill. TI recommends to verify these numbers with board manufacturing processes used in fabrication of the PCB. This footprint is available for download on the TPS65981 product folder on the TPS65981 product folder.

Figure 12-1 Top View Standard TPS65981 Footprint

Figure 12-2 Recommended Minimum Via Size