48V Buck Controller — what it is and where it fits
The Maxim Integrated MAX15157DATJ+ is a current-mode step-down (buck) controller for 48V distributed-power systems. It accepts an 8V to 60V input rail and drives an external N-channel MOSFET and Schottky diode.
50% duty cycle — the practical limit
The 50% max duty cycle is a hard ceiling: the output voltage cannot exceed roughly half the input. For a 48V nominal input, the practical output range tops out around 24V. If you need a higher output ratio — say 48V to 36V — this controller cannot deliver it; you would need a part with a higher duty-cycle limit or a different topology. For the common 48V-to-12V or 48V-to-5V step-down, the 50% limit is not a constraint.
Non-synchronous — external diode required
Because the MAX15157DATJ+ does not include a synchronous rectifier, the design must add an external Schottky catch diode. This adds one BOM line and PCB area, but lets the designer choose a diode rated for the actual load current and thermal environment.