Dual 5A buck — power budget and rail assignment
The TPS65279VRHHR is a dual-channel synchronous buck regulator from Texas Instruments, each channel rated for 5 A continuous output. The two channels share the same input supply and switch independently, so you can power a core rail and an I/O rail from one source without a second regulator IC.
Switching frequency — inductor sizing and EMI trade-off
At the high end you shrink the inductor and reduce board area, but the switching losses and the EMI filter design get tighter. At 200 kHz the inductor is larger but the efficiency peaks and the layout is more forgiving. The synchronous rectifier on both channels keeps the low-side drop low at full load, which matters when the output is down at 0.68 V and every millivolt of headroom counts.
36-VFQFN exposed pad — thermal and layout reality
The part lives in a 36-VFQFN package with a 6×6 mm body and an exposed thermal pad. Without the pad soldered, the junction temperature rises above the 85°C ambient ceiling at 5 A per channel. The 0.5 mm pitch on the QFN perimeter means the breakout traces need a 4-layer board if you route all 36 signals; a 2-layer board works only if you drop to the inner ring of pins and leave the outer ones as pass-through vias.