What the 42 V input and 200 kHz switching mean for your isolated rail
The MAX17681ATB+T is a step-down (buck) switching regulator from Analog Devices that accepts 4.5 V to 42 V on the input and delivers an adjustable output from 0.9 V up to 40.32 V. The 42 V ceiling covers 24 V industrial buses with margin for transients, and the 4.5 V minimum lets it start from a 5 V rail without a separate bias supply. Switching at 200 kHz, the regulator keeps the magnetics small enough for space-constrained designs while staying below the AM broadcast band where conducted emissions are harder to filter.
Temperature grade and package for the board designer
The output is adjustable and isolation-capable, meaning the regulator can drive a transformer primary to create a galvanically isolated secondary rail — useful when the load side must float relative to the input ground.