The LM25011 constant on-time step-down switching regulator features all the functionsneeded to implement a low-cost, efficient, buck bias regulator capable of supplying up to 2 A ofload current. This high-voltage regulator contains an N-Channel Buck switch, a startup regulator,current limit detection, and internal ripple control. The constant on-time regulation principlerequires no loop compensation, results in fast load transient response, and simplifies circuitimplementation. The operating frequency remains constant with line and load. The adjustable valleycurrent limit detection results in a smooth transition from constant voltage to constant currentmode when current limit is reached, without the use of current limit foldback. The PGD outputindicates the output voltage has increased to within 5% of the expected regulation value.Additional features include: Low output ripple, VIN under-voltage lock-out, adjustable soft-starttiming, thermal shutdown, gate drive pre-charge, gate drive under-voltage lock-out, and maximumduty cycle limit.
The LM25011A has a shorter minimum off-time than the LM25011, which allows for higherfrequency operation at low input voltages.