Three rails, two current ratings — what the load budget looks like
The TPS65581PWP is a triple-output synchronous buck regulator from TI's D-CAP2™ family, delivering 1.5 A on one output and 2.5 A on the other two. That 2.5 A rail is the one you budget for the hungriest load — core voltage on a processor, FPGA bank, or a string of peripheral drivers. The 1.5 A output handles the lighter analog or I/O rail.
700 kHz switching — inductor sizing trade-off
The fixed 700 kHz switching frequency sits in the middle of the typical 300 kHz–2 MHz range for multi-rail POL regulators. At 700 kHz the inductor value lands around 4.7 µH to 10 µH for the 2.5 A rail — small enough to fit a 5 mm × 5 mm shielded inductor, but not so fast that the switching losses eat into the efficiency at light load. The D-CAP2™ control loop gives fast transient response without external compensation, which simplifies the BOM and keeps the output capacitance down to a few ceramic caps per rail.
Industrial temperature range — where it survives
The 18 V input maximum covers 12 V and 24 V industrial buses with margin — just watch the derating if the input sits at 18 V continuously.
20-HTSSOP package — the thermal pad is not optional
The 0.65 mm pitch is fine for a two-layer board if you route the power traces on the top layer and use the bottom layer as the ground/thermal plane. The package width is 4.40 mm, so it fits in tight layouts alongside the output inductors.
The base product number TPS65581 covers the family; the PWP suffix identifies the 20-HTSSOP package and tube shipping medium.