1 Features

1• Ultrahigh Efficiency up to 97%

• High-Efficiency Over a 1.5-A to 1.5-mA Load

Range

• 4-V to 14-V Input Voltage Range

• 1.8-V, 2.5-V, 3.3-V, or ADJ Output Voltage

• Internal MOSFET Switch With Low RDS(on) of

75 mΩ

• 300-kHz Fixed Frequency Internal Oscillator

• 7-μA Shutdown Current

• Patented Current Sensing for Current Mode

Control

• Input Undervoltage Lockout

• Adjustable Soft-Start

• Current Limit and Thermal Shutdown

• 16-Pin TSSOP Package

2 Applications

• Personal Digital Assistants (PDAs)

• Computer Peripherals

• Battery-Powered Devices

• Handheld Scanners

• High-Efficiency 5-V Conversion

3 Description

The LM2651 switching regulator provides high-

efficiency power conversion over a 100:1 load range (1.5 A to 15 mA). This feature makes the LM2651 an

ideal fit in battery-powered applications that demand

long battery life in both run and standby modes.

Synchronous rectification is used to achieve up to

97% efficiency. At light loads, the LM2651 enters a

low power hysteretic or sleep mode to maintain high

efficiency. In many applications, the efficiency still

exceeds 80% at 15-mA load. A shutdown pin is

available to disable the LM2651 and reduce the

supply current to less than 10 μA.

The LM2651 contains a patented current sensing

circuitry for current mode control. This feature

eliminates the external current sensing resistor

required by other current-mode DC-DC converters.

The LM2651 has a 300-kHz fixed frequency internal

oscillator. The high oscillator frequency allows the

use of extremely small, low-profile components.

A programmable soft-start feature limits current

surges from the input power supply at start-up and provides a simple means of sequencing multiple

power supplies.

Other protection features include input undervoltage

lockout, current limiting, and thermal shutdown.