Buck-boost topology in a 24-QFN — what it means for the BOM
The LTC3643EUDD#PBF is a single-output buck-boost converter that regulates from an input voltage that can be above, below, or equal to the output voltage — this is the key differentiator from a pure buck or boost part. With a 3 V to 17 V input range and an adjustable output starting at 0.6 V, it handles battery-powered equipment where the cell voltage falls below the regulated rail, or automotive supplies that sag during cranking. The 2 A continuous output rating is the headline number for load sizing. At 1 MHz fixed switching frequency, the inductor value and output capacitor selection follow the standard buck-boost equations — the datasheet gives the component values for typical input/output combinations.
Package and temperature grade for the board
The 24-WFQFN exposed-pad package (3 mm × 5 mm body) requires a thermal land on the PCB to dissipate heat from the internal switches. Synchronous rectification is built in, which eliminates the external Schottky diode and improves efficiency at lower output voltages. The adjustable output allows setting the rail to any value from 0.6 V up to near the input voltage, limited by the maximum duty cycle of the topology.
Supplied in tube packaging, the part is compatible with pick-and-place assembly after the tube is loaded into a feeder.