The LM5009 step-down switching regulator features all the functions needed to implement a low-cost, efficient, buck bias power converter. This high-voltage regulator contains a 100-V N-channel buck switch, is easy to implement, and is provided in VSSOP-8 and thermally-enhanced, WSON-8 packages. The regulator is based on a control scheme using an on-time inversely proportional to V_IN. The control scheme requires no loop compensation. Current limit is implemented with forced off-time that is inversely proportional to V_OUT. This scheme ensures short-circuit protection and provides minimum foldback. The functional block diagram of the LM5009 is shown in the Section 7.2 section.

The LM5009 can be applied in numerous applications to efficiently regulate down higher voltages. This regulator is well-suited for 48-V telecom and 42-V automotive power bus ranges. Additional features include: thermal shutdown, V_CC undervoltage lockout, gate drive undervoltage lockout, maximum duty cycle limit timer, and the intelligent current limit off timer.