National Semi Debuts LM1770 Buck Switching Controller

Power management technology company National Semiconductor Corp. (Santa Clara, CA) debuted its new LM1770 SOT-23 synchronous buck switching controller for low-voltage dc-dc conversion, which utilizes constant on-time control, making it easy to employ because it does not require external compensation. The LM1770, packaged in the small SOT23-5, provides low-voltage, point-of-load regulation from standard 5 V and 3.3 V rails in space-constrained applications such as set-top boxes, cable modems, digital video recorders, and printers. The solution also replaces switching regulators and LDOs in enterprise server and point-of-sale applications.

The LM1770 controller features constant on-time control with easy-to-use topology that requires no external compensation; synchronous operation with a high-side PFET and low-side NFET that enable higher efficiency, resulting in reduced power dissipation; fast transient response that allows for fewer or smaller filter capacitors; an input-voltage range of 2.8 V to 5.5 V that is suitable for point-of-load regulation from a 3.3 V or 5 V rail; output voltage as low as 0.8 V that supports applications requiring less than 1 V power rails; internal soft-start that limits in-rush current and allows for a controlled startup; short-circuit protection that prevents damage to the application; and three on-time options that allow for selection of operating frequency range.

Available now, the LM1770 is priced at $0.95 in 1,000-unit quantities.