The LM25011 constant on-time step-down switching regulator features all the functions
needed to implement a low-cost, efficient, buck bias regulator capable of supplying up to 2 A of
load 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 principle
requires no loop compensation, results in fast load transient response, and simplifies circuit
implementation. The operating frequency remains constant with line and load. The adjustable valley
current limit detection results in a smooth transition from constant voltage to constant current
mode when current limit is reached, without the use of current limit foldback. The PGD output
indicates 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-start
timing, thermal shutdown, gate drive pre-charge, gate drive under-voltage lock-out, and maximum
duty cycle limit. The LM25011A has a shorter minimum off-time than the LM25011, which allows for higher
frequency operation at low input voltages.
