An important specification to consider in the device selection for a high voltage conversion design is the minimum on-time (Ton min). High voltage controllers typically have low Ton min allowing for designs such as 48Vin to 5Vout, 3.3Vout or lower.

Low Ton min is also important for designs requiring constant frequency switching to avoid interference with other frequency bands in your system. Frequency foldback occurs when the voltage conversion exceeds the minimum on-time specification at a certain switching frequency. This needs to be especially considered for systems that deal with voltage transients. LM5148-Q1 has a minimum on-time of around 50ns and LM70880-Q1 incorporates new IC innovation to offer an ultra-low minimum on-time of 25ns to handle a variety of high voltage conversion system challenges.