1.25 A automotive buck converter with wide input range
The ROHM BD90610EFJ-CE2 is a step-down (buck) switching regulator delivering 1.25 A continuous output from a 5 V to 36 V input rail, with an adjustable output down to 0.8 V.
Switching frequency and synchronous rectification
The switching frequency is programmable from 50 kHz to 500 kHz — a lower frequency reduces switching losses in the external diode (the part does not integrate synchronous rectification), while a higher frequency shrinks the inductor and output capacitor footprint. Because the BD90610EFJ-CE2 uses an external Schottky catch diode rather than a synchronous FET, the total efficiency depends on the diode forward voltage and the switching frequency trade-off; at 500 kHz the diode conduction losses dominate at light load.
The adjustable output uses an external resistor divider from the FB pin; the 0.8 V reference sets the minimum output, and the maximum output equals the input voltage minus the dropout of the internal switch.