11.1 Layout Guidelines
PCB layout is an important task in the power supply design. Good PCB layout minimizes EMI and allows very good output voltage regulation. For the TPS65132 the following PCB layout guidelines are recommended.
Keep the power ground plane on the top layer (all capacitor grounds and PGND pins must be connected together with one uninterrupted ground plane).
AGND and PGND must be connected together on the same ground plane.
Place the flying capacitor as close as possible to the IC.
- Always avoid vias when possible. They have high inductance and resistance. If vias are necessary, always use more than one in parallel to decrease parasitics especially for power lines.
Connect REG pins together.
- For high dv/dt signals (switch pin traces): keep copper area to a minimum to prevent making unintentional parallel plate capacitors with other traces or to a ground plane. Best to route signal and return on same layer.
- For high di/dt signals: keep traces short, wide and closely spaced. This will reduce stray inductance and decrease the current loop area to help prevent EMI.
- Keep input capacitor close to the IC with low inductance traces.
- Keep trace from switching node pin to inductor short if possible: it reduces EMI emissions and noise that may couple into other portions of the converter.
- Isolate analog signal paths from power paths.