1 Features

1• Input voltage 4.5 V to 42 V

• Output current options of 100 mA, 300 mA, and

600 mA

• Feedback pin voltage of 0.765 V

• 550-kHz (X) or 1.25-MHz (Y) switching frequency

• Low shutdown IQ: 16-μA typical

• Short-circuit protected

• Internally compensated

• Soft-start circuitry

• Small overall solution size (SOT-6L package)

• Create a custom design using the LM2840 (or

LM2841/42) with the WEBENCH® Power Designer

2 Applications

• Battery-powered equipment

• Industrial distributed power applications

• Portable media players

• Portable hand-held instruments

3 Description

The LM284x SIMPLE 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 of applications, such as power

conditioning from unregulated sources. They feature

a low RDSON (0.9‑Ω typical) internal switch for

maximum efficiency (85% typical). Operating

frequency is fixed at 550 kHz (X option) and

1.25 MHz (Y option), allowing the use of small

external components while still being able 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 the soft-start time to

a specific application.

The LM2840 is optimized for up to 100 mA, the

LM2841 for up to 300 mA, and the LM2842 for up to

600‑mA load currents. They all have a 0.765-V

nominal feedback voltage.

Additional features include: thermal shutdown, VIN

undervoltage lockout, and gate-drive undervoltage

lockout. The LM284x are available in a low-profile

SOT-6L package.