What the MAX668EUB+ does in a supply design
The Maxim Integrated MAX668EUB+ is a current-mode PWM controller that handles step-up, step-up/step-down, and isolated topologies — boost, flyback, and SEPIC. It drives an external transistor (single output, positive rail, isolation-capable) and runs from a 3V to 28V supply. The switching frequency is adjustable between 100kHz and 500kHz, with clock sync available for noise-sensitive multi-rail systems. Duty cycle maxes at 90%, and the controller includes enable and frequency control pins.
Where it fits in the BOM
This controller is a good fit for industrial and telecom supplies that need a non-isolated boost or an isolated flyback with a single transistor. The 3V to 28V input range covers 5V, 12V, and 24V rails commonly found in factory automation, motor drives, and outdoor telecom gear. The 100kHz to 500kHz switching band lets you trade inductor size against efficiency — 100kHz for lower switching losses, 500kHz for smaller magnetics.
For production BOMs, this part can be specified without an immediate obsolescence risk.