10.1 Layout Guidelines

1. Keep the input current loop as small as possible. And avoid the input switching current through the thermal pad.
2. Keep the SW node as physically small and short as possible to minimize parasitic capacitance and inductance and to minimize radiated emissions.
3. Keep analog and non-switching components away from switching components.
4. Make a single point connection from the signal ground to power ground.
5. Do not allow switching currents to flow under the device.
6. Keep the pattern lines for VINx and PGNDx broad.
7. Exposed pad of device must be soldered to PGND.
8. VREG5 capacitor must be placed near the device, and connected to GND.
9. Output capacitors must be connected with a broad pattern to the PGND.
10. Voltage feedback loops must be as short as possible, and preferably with ground shields.
11. Kelvin connections must be brought from the output to the feedback pin of the device.
12. Providing sufficient vias is preferable for VIN, SW, and PGND connections.
13. PCB pattern for VIN, SW, and PGND must be as broad as possible.
14. VIN capacitor must be placed as near as possible to the device.

10.2 Layout Example

Figure 25. TPS54295 PWP Package Layout

Figure 26. TPS54295 RSA Package Layout

10.3 Thermal Considerations

This 16-pin PWP package incorporates an exposed thermal pad. The thermal pad must be soldered directly to the printed-circuit board (PCB). After soldering, the PCB is used as a heat sink. In addition, through the use of thermal vias, the thermal pad can be attached directly to the appropriate copper plane shown in the electrical schematic for the device, or alternatively, can be attached to a special heat sink structure designed into the PCB. This design optimizes the heat transfer from the integrated circuit (IC).

For additional information on the exposed thermal pad and how to use the advantage of its heat dissipating abilities, see PowerPAD Thermally Enhanced Package and PowerPAD Made Easy.

The exposed thermal pad dimensions for this package are shown in Figure 27.

Figure 27. Thermal Pad Dimensions