Dual 3.5 A synchronous buck in a 6x6 mm QFN
The TPS65273VRHHT is a dual-output synchronous buck regulator from Texas Instruments, each output rated for 3.5 A continuous. The 36-VQFN (6x6) package with exposed pad packs two 3.5 A rails into a board footprint that fits alongside a 12 V or 15 V input bus. The input range spans 4.5 V to 18 V, so it works from a 5 V or 12 V pre-regulated rail but cannot start from a 3.3 V bus.
Switching frequency and efficiency trade-offs
The switching frequency is adjustable from 200 kHz to 1.6 MHz. Running at 1.6 MHz shrinks the inductor to a 0603 or 0805 footprint but increases switching losses; dropping to 200 kHz improves efficiency at the cost of a larger inductor. The synchronous rectifier helps maintain efficiency at the low end of the output range.
Package and layout checklist
The 36-VFQFN Exposed Pad (6x6 mm) requires a thermal land on the PCB — the datasheet recommends a 4.5 mm x 4.5 mm pad with at least nine thermal vias to the ground plane.