The LM284xSIMPLE SWITCHER™ devices are PWM DC/DC buck (step-down)regulators. With an input range from 4.5 V to 42 V, they are suitable for a wide range ofapplications, such as power conditioning from unregulated sources. They feature a lowRDSON (0.9‑Ω typical) internal switch for maximum efficiency(85% typical). Operating frequency is fixed at 550 kHz (X option) and1.25 MHz (Y option), allowing the use of small external components while still beingable to have low output voltage ripple. Soft start can be implemented using the shutdown(SHDN) pin with an external RC circuit allowing the user to tailor thesoft-start time to a specific application.
The LM2840 isoptimized for up to 100 mA, the LM2841 for up to 300 mA, and the LM2842 for up to 600‑mAload currents. They all have a 0.765-V nominal feedback voltage.
Additional features include: thermal shutdown, VIN undervoltagelockout, and gate-drive undervoltage lockout. The LM284x are available in a low-profile SOT-6L package.