Intended for use in applications such as handheld devices and automotive power adapters, the LM34917A and LM34919 step-down switching regulators from National Semiconductor is presented as the smallest devices of their type currently available. Features of the non-synchronous devices include, a peak efficiency equal to or greater than 90 percent, a programmable switching frequency of up to 2 MHz, a supply voltage rating up to 50 V, 1.25 A (LM34917A) or 0.6 A (LM34919) continuous output current, intelligent current limiting and over-voltage protection. Integrated MOSFET switches in the micro-SMD-packaged devices reduce system component count, and a constant on-time control scheme requires no loop compensation. Additional features include VCC under-voltage lockout, thermal shutdown, gate drive under-voltage lockout, and a maximum duty-cycle limiter. The LM34917A is priced at $1.35 each and the LM34919 is priced at $1.05 each in 1,000-unit quantities.