The TPS59632-Q1 device has an analog ground and a thermal pad. The usual procedure for connecting these is:
- Keep the analog GND of the device and the power GND of the power circuit separate. The device analog GND and the power circuit power GND can be connected at one single quiet point in the layout.
- The thermal pad does not have an electrical connection to device. But, the thermal pad must be connected to pin 29 GND of the device to give good ground shielding. Do not connect this to system GND.
- Tie the thermal pad to a ground island with at least 4 vias. All the analog components can connect to this analog ground island.
- The analog ground can be connected to any quiet spot on the system ground. A quiet spot is defined as a spot where no power supply switching currents are likely to flow. Use a single point connection from analog ground to the system ground.
- Make sure the bottom FET source connection and the input decoupling capacitors have plenty of vias.